Universe Today

A beautiful nebula in the southern hemisphere with a binary star at it’s center seems to break our standard models of stellar evolution. But new data from the European Southern Observatory (ESO) suggests that there may once have been three stars, and that one was destroyed in a catastrophic collision.

About 3800 light years away, in the Southern constellation of Norma, you can find an object called the Dragon’s Egg Nebula (catalogue number NGC 6164). In the heart of this nebula lies a double star known as HD 148937. The pair are bright enough to be seen through binoculars and small telescopes but are far enough away that they only appear as a single star. Both of the stars that make up the pair are hot young blue giants, but the nebula surrounding them is quite unusual, which is why astronomers have been studying them for a long time.

Dr Abigail Frost is an astronomer at the European Southern Observatory (ESO) in Chile, and she has been paying attention to this system for the past nine years.

“When doing background reading, I was struck by how special this system seemed,” she says. “A nebula surrounding two massive stars is a rarity, and it really made us feel like something cool had to have happened in this system. When looking at the data, the coolness only increased.”

Frost, like other astronomers before her, have noticed many strange features about the nebula. Most obviously, hot young stars like these aren’t usually found in nebulae, as their intense radiation tends to disperse surrounding dust and gas quite efficiently. But beyond that, the nebula itself has an unusual composition. If this nebula were the remains of the gas cloud that birthed these stars, it would be composed almost entirely of molecular hydrogen. But instead, it contains heavier elements like oxygen, nitrogen and carbon. Old stars create these elements by fusing Helium, and they eject them in their final stages of life. But that cannot be the source of this nebula, as the stars are still young.

The stars themselves have their own mysteries. The larger of the two has a strong magnetic field. Magnetic fields in stars like our Sun are formed when the thick central shell of super-heated plasma circulates. Much of the heat from the Sun’s core is transferred to the surface by convection: hot plasma near the core bubbles up towards the surface, where it cools and then sinks back down. Plasma is electrically charged, and all that charge moving generates a magnetic field, in what scientists call a dynamo effect.

But truly massive stars, like those in HD 148937, are so big that heat can simply radiate out from the core. There is such a large distance from the core to the surface that the temperature gradient is very gradual. There is nowhere inside the star with a high enough temperature differential to start convection, so there is no flow of material to generate a magnetic field. Nevertheless, the star has a magnetic field, which leads to the next oddity: magnetic stars experience a braking effect, causing their spin to gradually slow. So, this star, with its strong magnetic field which it should not have, spins rapidly, which the magnetic field should have prevented.

Fighting Dragons of Ara (NGC 6188 and 6164) © Michael Sidonio

But that’s not all! The primary star is at least 1.5 million years younger than its companion. According to Dr Frost, this shouldn’t be possible: “After a detailed analysis, we could determine that the more massive star appears much younger than its companion, which doesn’t make any sense since they should have formed at the same time”

If this system of stars and nebula doesn’t match what our models of stellar evolution tell us to expect, then how do we explain all these anomalies?

“We think this system had at least three stars originally; two of them had to be close together at one point in the orbit whilst another star was much more distant,” explains Hugues Sana, a professor at KU Leuven in Belgium and the principal investigator of the observations. “The two inner stars merged in a violent manner, creating a magnetic star and throwing out some material, which created the nebula. The more distant star formed a new orbit with the newly merged, now-magnetic star, creating the binary we see today at the centre of the nebula.”

In other words, the system was originally a triple star, not a double. Triple systems tend to be quite unstable, and usually end up ejecting one of their members. But sometimes the third star will smash dramatically into one of its companions instead. Nobody has ever seen a stellar collision, but computer modelling predicts a number of things, which we see in NGC 6164. A star is, essentially, a vast and massive cloud of gas, so big and heavy that its central regions are compressed to an enormous temperature and pressure. So, when two stars collide, these masses of gas merge chaotically. The different layers mix, dredging nuclear ash (like helium, nitrogen, carbon and oxygen) from the core to the surface. A lot of the gas, including the heavier elements, is ejected to create a vast new nebula. What’s left will collapse back inwards, settling down into a new star, with a rapid spin to match. And finally, the turbulence of the collision generates and sustains a powerful magnetic field.

This sequence of events has long been predicted by astronomers trying to model stellar mergers, and the nine years of work by Dr Frost could well provide the evidence to confirm that they are right. The metal-rich gas of NGC 6164, the youthful appearance of the primary star, it’s rapid spin and strong magnetic field all seem to confirm that this was indeed once a three body system that ended with a collision between two stars.

Read the original press release at https://www.eso.org/public/news/eso2407/

The post Two Stars in a Binary System are Very Different. It's Because There Used to be Three appeared first on Universe Today.

The history of astronomy and observatories is full of stories about astronomers going higher and higher to get better views of the Universe. On Earth, the best locations are at places such as the Atacama Desert in Chile. So, that’s where the University of Tokyo Atacama Observatory just opened its high-altitude eye on the sky, atop Cerro Chajnantor.

This unique new observatory, which was just commissioned on April 30th, sits at 5,640 meters (3.5 miles) above sea level, making it the highest observatory in the world—with a Guinness World Record recognition to prove it. The idea is to use this position in one of the driest areas of the world to get a closer look at planet-forming regions, evolving galaxies, and the earliest accessible epochs of cosmic history.

“Thanks to the height and arid environment, TAO will be the only ground-based telescope in the world capable of clearly viewing mid-infrared wavelengths. This area of the spectrum is extremely good for studying the environments around stars, including planet-forming regions,” said Professor Takashi Miyata, director of the Atacama Observatory of the Institute of Astronomy and manager of the observatory’s construction.

Building an observatory at such a high altitude may give astronomers a great view, but it’s also is a difficult place to work. For that reason, the University cooperated closely with locals to build the observatory safely. It will be operated remotely as much as possible, to avoid risking human life in what can be very adverse conditions.

At 5,640 meters, the summit of Cerro Chajnantor, where Tokyo Atacama Observatory is located, allows the telescope to be above most of the moisture that would otherwise limit its infrared sensitivity. ©2024 TAO project CC-BY-ND Why a Mid-infrared Observatory?

Objects and events in the Universe give off light across the electromagnetic spectrum. On Earth, we can detect much of that light, but not all of it. For example, Earth’s atmosphere absorbs many infrared wavelengths. So, the higher a telescope is placed, the more infrared it can “see”. Going to space (as astronomers have done with JWST, for example) is great, and a lot gets accomplished there. But astronomers can do quite a lot of very good astronomy at high altitudes, where conditions are dry and the atmosphere is thinner.

Mid-infrared is a particularly interesting “regime” of the electromagnetic spectrum. This is where we can start to “see” objects such as asteroids and planets. They re-radiate heat from their stars in the mid-infrared range. The same thing happens with dust around stars. It gets warmed and re-radiates in the mid-infrared. Disks of material around newborn stars—called protoplanetary disks—give off infrared radiation. Since these disks are where new planets form, infrared views give more detail about their evolution.

Mid-infrared studies of distant galaxies offer insight into their formation histories, as well as their star-formation rates. In addition, that range of wavelengths opens up a window into the activities and existence of active galactic nuclei. And, there’s a lot more that mid-infrared observations of the Universe can tell astronomers.

TAO Specs

According to Professor Yuzuru Yoshii, the TAO project lead and principal investigator, the new observatory should provide unique insights at each wavelength it studies. “I’m seeking to elucidate mysteries of the Universe, such as dark energy and primordial first stars,” said Yoshii. “For this, you need to view the sky in a way that only TAO makes possible.”

A schematic of the Tokyo Atacama Observatory telescope. Courtesy TAO project.

The heart of TAO is a 6.5-meter mirror that will feed incoming light into specialized instruments. The Simultaneous-color Wide-field Infrared Multi-object Spectrograph (SWIMS) can observe a large area of the sky and simultaneously observe two wavelengths of light. The other is the Mid-Infrared Multi-field Imager for gaZing at the UnKnown Universe (MIMIZUKU). It peers into the dustier regions of the Universe. Both will allow astronomers to efficiently collect information on a diverse range of galaxies and other structures in the Universe.

“Analysis of the SWIMS observation data will provide insight into the formation of these including the evolution of the supermassive black holes at their centers,” said Assistant Professor Masahiro Konishi. “New telescopes and instruments naturally help advance astronomy. I hope the next generation of astronomers use TAO and other ground-based, and space-based, telescopes, to make unexpected discoveries that challenge our current understanding and explain the unexplained.”

For More Information

The TAO Project
World’s Highest Observatory Explores the Universe

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The JWST keeps one-upping itself. In the telescope’s latest act of outdoing itself, it examined a distant exoplanet to map its weather. The forecast?

An unending, blistering inferno driven by ceaseless supersonic winds.

WASP-43b is a hot Jupiter orbiting a main sequence star about 261 light-years away. It has a slightly larger radius than Jupiter and is about twice as massive. It orbits its star in under 20 hours and is only 1.3 million miles away from it. That means it is tidally locked to the star, with one side facing all the radiation and the other permanently dark.

This is not unusual for exoplanet gas giants. They’re often tight to their stars and don’t rotate.

WASP-43b’s discovery was announced in 2011. Since then, astronomers have studied it extensively. In 2019, researchers captured its spectrum and reported water in its clouds. Conversely, no methane, carbon dioxide, or carbon monoxide were detected. Further research showed that mineral particles dominate its clouds. The Hubble Space Telescope was largely responsible for these results; other telescopes like the Spitzer also contributed.

Scientists knew that when the JWST was launched, it would eventually turn its eye toward WASP-43b. “Having a short orbital period and being tidally locked makes WASP-43b an ideal candidate for JWST observations,” explained the authors of a 2020 paper. “Phase curve observations of an entire orbit will enable the mapping of the atmospheric structure across the planet, with different wavelengths of observation allowing different atmospheric depths to be seen.” Their paper anticipated what the JWST might find and how its observations might be understood.

Now, we’re in the future, and the JWST has taken a look at WASP-43b and captured more detailed observations than ever. The space telescope’s powerful infrared capabilities measured the heat on both sides of the planet and allowed the mapping of the planet’s atmospheric structure, just as the authors of the 2020 paper stated.

“The fact that we can map temperature in this way is a real testament to Webb’s sensitivity and stability.”

Michael Roman, University of Leicester.

A new paper in Nature Astronomy presents the results. It’s titled “Nightside Clouds and Disequilibrium Chemistry on the Hot Jupiter WASP-43b.” The lead author is Taylor Bell, a researcher from the Bay Area Environmental Research Institute.

“With Hubble, we could clearly see that there is water vapour on the dayside. Both Hubble and Spitzer suggested there might be clouds on the nightside,” explained lead author Bell. “But we needed more precise measurements from Webb to really begin mapping the temperature, cloud cover, winds, and more detailed atmospheric composition all the way around the planet.”

Despite its power, the JWST can’t directly see WASP-43b. Instead, it utilizes phase curve spectroscopy. Phase curve spectroscopy measures the light from the planet and the star over time, sensing small changes in the light from both as the planet orbits the star. Since the JWST senses infrared light, which is emitted depending on an object’s heat, the telescope’s varying brightness data expresses the planet’s temperature.

Phase curve spectroscopy allows the JWST to sense the change in brightness as a planet orbits its star. This diagram shows the change in a planet’s phase (the amount of the lit side facing the telescope) as it orbits its star. Image Credit: NASA, ESA, CSA, Dani Player (STScI), Andi James (STScI), Greg Bacon (STScI)

The JWST’s MIRI spectrometer captured WASP-43b’s phase curve. The planet is hottest when it’s on the opposite side of the star and its lit-up side faces the telescope. The telescope sees the cooler dark side when the planet is on this side of the star and transiting in front of it.

This graph shows more than 8,000 measurements of mid-infrared light captured over a single 24-hour observation using the JWST’s low-resolution spectroscopy mode on its MIRI (Mid-Infrared Instrument). By subtracting the amount of light the star contributes, astronomers can calculate the amount coming from the visible side of the planet as it orbits. The telescope’s extreme sensitivity made this possible. Webb detected differences in brightness as small as 0.004% (40 parts per million). Image Credit: NASA, ESA, CSA, Ralf Crawford (STScI)

“By observing over an entire orbit, we were able to calculate the temperature of different sides of the planet as they rotate into view,” explained Bell. “From that, we could construct a rough map of temperature across the planet.”

To put the data into perspective, the researchers compared WASP-43b’s phase curve to General Circulation Model (GCM) simulations. The JWST phase curve data more closely matched a cloudy GCM than a cloudless GCM.

“The cloudy models are able to suppress the nightside emission and better match the data,” the authors explain in their paper.

This figure from the research shows the JWST’s phase curve data for WASP-43b (black dots) and what cloudless and cloudy GCM simulations predict. The data more closely matches a cloudy atmosphere. Image Credit: Bell et al. 2024.

The researchers used the detailed infrared data to construct a temperature map of the exoplanet. The dayside has an average temperature of about 1,250 Celsius (2,300 F), which is almost hot enough to forge iron. But the nightside likely has a thick layer of high-altitude clouds that trap some of the heat. Those clouds make the nightside appear cooler than it is. It’s much cooler at about 600 degrees Celsius (1,100 degrees Fahrenheit) but still hot enough to melt aluminum.

“The fact that we can map temperature in this way is a real testament to Webb’s sensitivity and stability,” said Michael Roman, a co-author from the University of Leicester in the U.K.

This set of maps shows the temperature of the visible side of the hot gas-giant exoplanet WASP-43 b as the planet orbits its star. Image Credits: Illustration: NASA, ESA, CSA, Ralf Crawford (STScI). Science:
Taylor Bell (BAERI), Joanna Barstow (The Open University), Michael Roman (University of Leicester)

The researchers also mapped a hot spot in WASP-43b’s atmosphere, and it helped them gauge the exoplanet’s ferocious winds. The hot spot is east of the point receiving the most starlight. That means that powerful winds are moving the heated gas.

The JWST’s spectrum also allowed the researchers to measure the presence of water vapour (H2O) and methane (CH4.) “Webb has given us an opportunity to figure out exactly which molecules we’re seeing and put some limits on the abundances,” said Joanna Barstow, a co-author from the Open University in the U.K.

Webb found water vapour on the dayside and the nightside, indicating cloud thickness and elevation. However, the telescope detected an absence of methane (CH4), which is unusual. The extreme heat on the dayside means carbon is in carbon monoxide (CO) form. But the cooler nightside should contain stable methane. Why isn’t it there? Powerful winds are responsible.

“The fact that we don’t see methane tells us that WASP-43b must have wind speeds reaching something like 5,000 miles per hour,” explained Barstow. “If winds move gas around from the dayside to the nightside and back again fast enough, there isn’t enough time for the expected chemical reactions to produce detectable amounts of methane on the nightside.”

via GIPHY

Previous observations with the Hubble, Spitzer, and others revealed some aspects of WASP-43b’s atmosphere. But the JWST has taken it a step further. By determining the extremely high wind velocity on the exoplanet, scientists now believe the atmosphere is the same all around the planet.

“Taken together, our results highlight the unique capabilities of JWST/MIRI for exoplanet atmosphere characterization,” the authors write in their paper. They point out that there are still some discrepancies between the phase curve, the GCM simulations, and the chemical equilibrium in the atmosphere.

According to the researchers, more JWST exoplanet observations can help resolve them. “These remaining discrepancies underscore the importance of further exploring the effects of clouds and disequilibrium chemistry in numerical models as JWST continues to place unprecedented observational constraints on smaller and cooler planets,” they conclude.

The post Is the JWST Now an Interplanetary Meteorologist? appeared first on Universe Today.

You’ve seen the Sun, but you’ve never seen the Sun like this. This single frame from a video captured by ESA’s Solar Orbiter mission shows the Sun looking very …. fluffy!  You can see feathery, hair-like structures made of plasma following magnetic field lines in the Sun’s lower atmosphere as it transitions into the much hotter outer corona. The video was taken from about a third of the distance between the Earth and the Sun.

See the full video below, which shows unusual features on the Sun, including coronal moss, spicules, and coronal rain.  

Solar Orbiter recorded this video on September 27, 2023 using its Extreme Ultraviolet Imager (EUI) instrument.

ESA said the brightest regions are around one million degrees Celsius, while cooler material looks darker, as it absorbs radiation.

So, just what is coronal moss? It’s what gives the Sun its fluffy appearance here. These peculiar structures on the Sun resemble the moss we find on Earth, in that it appears like fine, lacy features. But on the Sun, they usually can be found around the center of sunspot groups, where magnetic conditions are strong and large coronal loops are forming. The moss is so hot, most instruments can’t detect them. The moss spans two atmospheric layers, the chromosphere and corona.

Features on the Sun’s surface, as seen by Solar Orbiter. Credit: ESA & NASA/Solar Orbiter/EUI Team

Spicules, as their name implies, are tall spires of gas seen on the solar horizon that reach up from the Sun’s chromosphere. These can reach up to a height of 10,000 km (6,000 miles).

At about 0:30 in the video, you’ll see coronal rain. This material is cooler than the rest of the solar surface (probably less than 10,000 °C) versus the one million degrees C of the coronal loops. The rain is made of higher-density clumps of plasma that fall back towards the Sun under the influence of gravity.

Did you see the small eruption in the center of the field of view at about 0:20 seconds in the video? , with cooler material being lifted upwards before mostly falling back down. It’s not small at all — this eruption is bigger than Earth!

Missions like Solar Orbiter, the Parker Solar Probe and the Solar Dynamics Observatory are giving us unprecedented views of the Sun, helping astronomers to learn more about the dynamic ball of gas that powers our entire Solar System.

Further reading: ESA

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Artificial intelligence and machine learning have become ubiquitous, with applications ranging from data analysis, cybersecurity, pharmaceutical development, music composition, and artistic renderings. In recent years, large language models (LLMs) have also emerged, adding human interaction and writing to the long list of applications. This includes ChatGPT, an LLM that has had a profound impact since it was introduced less than two years ago. This application has sparked considerable debate (and controversy) about AI’s potential uses and implications.

Astronomy has also benefitted immensely, where machine learning is used to sort through massive volumes of data to look for signs of planetary transits, correct for atmospheric interference, and find patterns in the noise. According to an international team of astrophysicists, this may just be the beginning of what AI could do for astronomy. In a recent study, the team fine-tuned a Generative Pre-trained Transformer (GPT) model using observations of astronomical objects. In the process, they successfully demonstrated that GPT models can effectively assist with scientific research.

The study was conducted by the International Center for Relativistic Astrophysics Network (ICRANet), an international consortium made up of researchers from the International Center for Relativistic Astrophysics (ICRA), the National Institute for Astrophysics (INAF), the University of Science and Technology of China, the Chinese Academy of Sciences Institute of High Energy Physics (CAS-IHEP), the University of Padova, the Isfahan University of Technology, and the University of Ferrera. The preprint of their paper, “Test of Fine-Tuning GPT by Astrophysical Data,” recently appeared online.

Illustration of an active quasar. New research shows AI can identify and classify them. Credit: ESO/M. Kornmesser

As mentioned, astronomers rely extensively on machine learning algorithms to sort through the volumes of data obtained by modern telescopes and instruments. This practice began about a decade ago and has since grown by leaps and bounds to the point where AI has been integrated into the entire research process. As ICRA President and the study’s lead author Yu Wang told Universe Today via email:

“Astronomy has always been driven by data and astronomers are some of the first scientists to adopt and employ machine learning. Now, machine learning has been integrated into the entire astronomical research process, from the manufacturing and control of ground-based and space-based telescopes (e.g., optimizing the performance of adaptive optics systems, improving the initiation of specific actions (triggers) of satellites under certain conditions, etc.), to data analysis (e.g., noise reduction, data imputation, classification, simulation, etc.), and the establishment and validation of theoretical models (e.g., testing modified gravity, constraining the equation of state of neutron stars, etc.).”

Data analysis remains the most common among these applications since it is the easiest area where machine learning can be integrated. Traditionally, dozens of researchers and hundreds of citizen scientists would analyze the volumes of data produced by an observation campaign. However, this is not practical in an age where modern telescopes are collecting terabytes of data daily. This includes all-sky surveys like the Very Large Array Sky Survey (VLASS) and the many phases conducted by the Sloan Digital Sky Survey (SDSS).

To date, LLMs have only been applied sporadically to astronomical research, given that they are a relatively recent creation. But according to proponents like Wang, it has had a tremendous societal impact and has a lower-limit potential equivalent to an “Industrial Revolution.” As for the upper limit, Wang predicts that that could range considerably and could perhaps result in humanity’s “enlightenment or destruction.” However, unlike the Industrial Revolution, the pace of change and integration is far more rapid for AI, raising questions about how far its adoption will go.

The Sloan Digital Sky Survey telescope stands out against the breathtaking backdrop of the Sacramento Mountains. Credit: SDSS/Fermilab Visual Media Services

To determine its potential for the field of astronomy, said Wang, he and his colleagues adopted a pre-trained GPT model and fine-tuned it to identify astronomical phenomena:

“OpenAI provides pre-trained models, and what we did is fine-tuning, which involves altering some parameters based on the original model, allowing it to recognize astronomical data and calculate results from this data. This is somewhat like OpenAI providing us with an undergraduate student, whom we then trained to become a graduate student in astronomy. 

“We provided limited data with modest resolution and trained the GPT fewer times compared to normal models. Nevertheless, the outcomes are impressive, achieving an accuracy of about 90%. This high level of accuracy is attributable to the robust foundation of the GPT, which already understands data processing and possesses logical inference capabilities, as well as communication skills.”

To fine-tune their model, the team introduced observations of various astronomical phenomena derived from various catalogs. This included 2000 samples of quasars, galaxies, stars, and broad absorption line (BAL) quasars from the SDSS (500 each). They also integrated observations of short and long gamma-ray bursts (GRBs), galaxies, stars, and black hole simulations. When tested, their model successfully classified different phenomena, distinguished between types of quasars, inferred their distance based on redshift, and measured the spin and inclination of black holes.

“This work at least demonstrates that LLMs are capable of processing astronomical data,” said Wang. “Moreover, the ability of a model to handle various types of astronomical data is a capability not possessed by other specialized models. We hope that LLMs can integrate various kinds of data and then identify common underlying principles to help us understand the world. Of course, this is a challenging task and not one that astronomers can accomplish alone.”

The Vera Rubin Observatory at twilight on April 2021. It’s been a long wait, but the observatory should see first light later this year. Credit: Rubin Obs/NSF/AURA

Of course, the team acknowledges that the dataset they experimented with was very small compared to the data output of modern observatories. This is particularly true of next-generation facilities like the Vera C. Rubin Observatory, which recently received its LSST camera, the largest digital camera in the world! Once Rubin is operational, it will conduct the ten-year Legacy Survey of Space and Time (LSST), which is expected to yield 15 terabytes of data per night! Satisfying the demands of future campaigns, says Wang, will require improvements and collaboration between observatories and professional AI companies.

Nevertheless, it’s a foregone conclusion that there will be more LLM applications for astronomy in the near future. Not only is this a likely development, but a necessary one considering the sheer volumes of data astronomical studies are generating today. And since this is likely to increase exponentially in the near future, AI will likely become indispensable to the field of study.

Further Reading: arXiv

The post What Can AI Learn About the Universe? appeared first on Universe Today.

The Search for Life in our Solar System leads seekers to strange places. From our Earthbound viewpoint, an ice-covered moon orbiting a gas giant far from the Sun can seem like a strange place to search for life. But underneath all that ice sits a vast ocean. Despite the huge distance between the moon and the Sun and despite the thick ice cap, the water is warm.

Of course, we’re talking about Enceladus, and its warm, salty ocean—so similar to Earth’s in some respects—takes some of the strangeness away.

Enceladus is Saturn’s sixth-largest moon, and the Cassini spacecraft observed it during its mission to the Saturn system. Scientists discovered that plumes of water originating from Enceladus’ southern region are responsible for one of Saturn’s rings. They also discovered that the water is salty. Any place we find warm, salty water attracts our immediate attention, even when it’s covered by kilometres of ice and is 1.5 billion kilometres away from the life-giving Sun.

There’s lots of talk about a future mission to Enceladus to explore the moon and its potentially life-supporting ocean in more detail. But until then, scientists are working with their current data, and using models and simulations to understand the moon better.

Enceladus’ most defining surface features are its Tiger Stripes. They’re four parallel, linear depressions on the moon’s surface about 130 km long, 2 km wide, and 500 meters deep. They have higher temperatures than their surroundings, indicating that cryovolcanism is active. The stripes are the source of Enceladus’ plumes.

Geysers erupt from Enceladus’ Tiger Stripes in this image from the Cassini spacecraft. Image Credit: By NASA/JPL/SSI – http://www.nasa.gov/mission_pages/cassini/multimedia/pia11688.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=15592605

New research suggests that strike-slip faults at the moon’s prominent Tiger Stripe features allow plumes of water from Enceladus to escape into space. It’s published in Nature Geoscience and titled “Jet activity on Enceladus linked to tidally driven strike-slip motion along tiger stripes.” The lead author is Alexander Berne, a doctoral candidate in Geophysics at the California Institute of Technology.

The plumes above the Tiger Stripes aren’t stable and continuous. They wax and wane as the moon follows its 33-hour orbit around Saturn. Tidal heating keeps the moon’s water in liquid form, and according to the researchers, the same tidal forces are responsible for the intermittent plumes. Theory shows that tidal forces open and close faults at the Tiger Stripes like an elevator door, and that turns the plumes on and off.

However, those theories can’t accurately predict the timing of the plumes’ peak brightness. They also show that tidal forcing alone doesn’t provide enough energy to open and close the faults.

This research digs deeper into the question and provides an answer. The authors say that rather than acting like an elevator door, strike-slip faults at the Tiger Stripes open and close to regulate plume activity. This is similar to what happens on Earth in places like the San Andreas Fault. It’s a strike-slip fault where one side shears past the other, causing Earthquakes. The critical part of this is that strike-slip faults require less energy than the elevator opening and closing scenario.

Models are more effective as they’re fed more detailed and accurate data. Berne and his co-researchers built a numerical model that simulates the strike-skip faults on Enceladus. They included friction, compressional forces and shear forces. The numerical model showed the faults acting in concert with the changing plumes. This strongly suggests that Enceladus’ orbit and the tidal forces acting on the moon cause the strike-slip faults to open and close.

This illustration from the research explains how strike-slip faults are responsible for the plumes erupting from Enceladus’ Tiger Stripes. As the moon orbits Saturn, tidal forces open and close the faults. Image Credit: Berne et al. 2024.

The Tiger Stripes have bent sections that pull apart under strain. Since they’re bent, an opening appears as they slide. The plumes come from these openings.

The research team’s work and previous research into the Tiger Stripes by NASA’s Jet Propulsion Laboratory both support the idea that the plumes come from these strike-slip faults.

“We now appear to have both geologic and geophysical reasons to suspect that jet activity occurs at pull-aparts along Enceladus’s tiger stripes,” said lead author Berne.

This figure from the research shows the degree of displacement and slip at the Tiger Stripe faults at two different points in Enceladus’ orbit. Image Credit: Berne et al. 2024.

Enceladus gets most of its attention because of its potential to support life. The plumes themselves aren’t part of what life needs, but they’re a window into the moon’s potential habitability.

“For life to evolve, the conditions for habitability have to be right for a long time, not just an instant,” said study co-author Mark Simons, Professor of Geophysics at Caltech. “On Enceladus, you need a long-lived ocean. Geophysical and geological observations can provide key constraints on the dynamics of the core and the crust as well as the extent to which these processes have been active over time.”

There’s a lot more work to be done to understand Enceladus. On Earth, satellites can monitor the movement at strike-slip faults and use it to better understand Earthquakes. Once we get a spacecraft to Enceladus, it could do the same.

“Detailed measurements of motion along the tiger stripes are needed to confirm the hypotheses laid out in our work,” Berne says. “For instance, we now have the capacity to image fault slip, such as earthquakes, on Earth using radar measurements from satellites in orbit. Applying these methods at Enceladus should allow us to better understand the transport of material from the ocean to the surface, the thickness of the ice crust, and the long-term conditions which may enable life to form and evolve on Enceladus.”

When we get a spacecraft to Enceladus, it can monitor the faults and jets over multiple orbits. That will allow researchers to test their predictions.

“These observations could provide key constraints on the mechanical nature of the crust, tidal controls on jet activity and the evolution of the south polar terrain,” the authors conclude.

The post Enceladus’s Fault Lines are Responsible for its Plumes appeared first on Universe Today.

Few things in life are certain. But it seems highly probable that people will explore the lunar surface over the next decade or so, staying there for weeks, perhaps months, at a time. That fact bumps up against something we are certain about. When human beings spend time in low-gravity environments, it takes a toll on their bodies.

What can be done?

Scientists have studied the effects of microgravity and low gravity on the human body. Several problems crop up, like muscle atrophy and bone demineralization. Cardiovascular conditioning suffers, as does neural control of body posture and movement. But while researchers are learning more and more about the effects, solutions are lagging behind.

A new paper published in Royal Society Open Science suggests a novel, low-tech solution for these problems. Its title is “Horizontal running inside circular walls of Moon settlements: a comprehensive countermeasure for low-gravity deconditioning?” The lead author is Alberto Minetti, a Physiology Professor at the University of Milan.

Minetti and his co-authors point out that specific exercises for specific problems may not be the best approach. Instead, whole-body exercise could be a powerful tool for supporting astronaut health. “Rather than training selected muscle groups only, ‘whole-body’ activities such as locomotion seem better candidates,” they explain. However, there’s a problem with that. “But at Moon gravity, both ‘pendular’ walking and bouncing gaits like running exhibit abnormal dynamics at faster speeds,” they write.

The abnormal dynamics mean that astronauts don’t benefit much from that type of exercise. It’s hindered by an ” … imbalance between the kinetic and potential energy of the body centre of mass,” the authors write. That means it can’t be used to get the same kind of exercise it would provide on the Earth. “Additionally, the metabolic demands of bouncing gaits are reduced at Moon gravity, limiting their potential stimulus for cardiorespiratory fitness,” the authors explain.

There are some potential solutions out there to help lunar astronauts maintain their health in low gravity. One is a centrifuge, where the rotating motion simulates gravity, encouraging the body to maintain muscle and bone mass. But they’re energy-intensive and impractical.

The authors are proposing a novel solution. Have you ever seen a Wall of Death?

A stuntman riding on a Wall of Death. Friction and centripetal force allow him to ride on the wall’s vertical surface. Image Credit: By SeaDave from Fairlie, Scotland – Owner of the Wall of Death, in his family for 80 years.Uploaded by MaybeMaybeMaybe, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=22817835

“Here, we propose a novel solution: lunar inhabitants could engage in running on the inside of vertical circular walls, hence running parallel to the Moon’s surface,” the authors write. Exercising in a Wall of Death (WoD) would help maintain muscle mass, bone density, cardiovascular fitness, and neural control.

On Earth, the gravity is too strong for humans to run around the sides of a WoD. Only motorized vehicles and bicycles can do it. But on the Moon, the weaker gravity makes them practical.

The researchers simulated a lunar WoD and tested the performance of subjects running in it. They hired a WoD for one day and used a harness of bungee cords to reduce participants’ body weight, simulating the Moon’s lower gravity.

The researchers removed the roof from the WoD and used a crane to support the harness. The middle inset image is unrelated to the research and illustrates the peculiar upward leaning posture of someone in the WoD. Image Credit: Minetti et al. 2024.

Two participants took part in the tests: a 36-year-old man and a 33-year-old woman. The bungees were tuned so each participant weighed one-sixth of their body weight. The harness unloaded one side of the subjects’ bodies to further mimic lunar conditions. Each participant’s data from the WoD was combined with treadmill data to give robust results.

Once inside the WoD and connected to the harness, this is what the experiment looked like.

In this image, the 33-year-old female subject is connected to the harness and running around the inside of the Wall of Death. Image Credit: Minetti et al. 2024.

The participants quickly got the hang of the unusual motion required to run horizontally inside the WoD. “This process required only 5–8 attempts and allowed them to start running with no assistance,” the authors write. The participants “… ended their performance by safely slowing down their pace and descending from the horizontal posture on the wall down to the upright one on the WoD floor, with no injuries,” they explained.

via GIPHY

The authors say they’ve successfully demonstrated the basics of using a WoD to support lunar astronaut health. “We have demonstrated for the first time that humans can safely run horizontally in low gravity conditions inside a cylinder, sized as a terrestrial ‘WoD’, through a speed-driven, self-generated higher artificial gravity,” they explain.

The researchers are confident that the Wall of Death idea can help lunar astronauts deal with the chronic effects of lunar gravity. At the same time, they’re cognizant of their small sample size and the study’s other limitations.

“In conclusion, while being aware of the small sample size, of the crudeness of kinematics acquisition in such a peculiar field experiment, and that dedicated bed rest studies will be needed to refine this topic, we are confident in our findings,” they write in their conclusion.

Though normal running on the Moon is impossible, the WoD provides a way to gain the benefits of running in short WoD exercise sessions daily. Participants using the WoD created “… a sufficiently high (lateral) self-generated artificial gravity likely capable of maintaining, through a few short, almost ‘terrestrial’ running laps a day, an acceptable cardio-motor fitness and bone mineral status, useful to locally move and work around, to prepare the long trip to Mars, and to return home in good condition.”

There’s an elegance around low-tech solutions to confounding problems. A simple WoD could be the solution to the Moon’s low gravity instead of a complicated, energy-hungry device like a centrifuge.

“All of this, by using an inexpensive and passive facility already built in their circular inhabited units,” the authors conclude.

The post Lunar Explorers Could Run to Create Artificial Gravity for Themselves appeared first on Universe Today.

Space debris is a growing problem, so companies are working on ways to mitigate it. A new satellite called ADRAS-J was built and launched to demonstrate how a spacecraft could rendezvous with a piece of space junk, paving the path for future removal. Astroscale Japan Inc, the Japanese company behind the satellite, released a new picture from the mission showing a close image of its target space debris, a discarded Japanese H2A rocket’s upper stage, captured from just a few hundred meters away.

ADRAS-J stands for Active Debris Removal by Astroscale-Japan, and is the first satellite ever to attempt to safely approach, characterize and survey the state of an existing piece of large debris. This mission will only demonstrate Rendezvous and Proximity Operations (RPO) capabilities by operating in near proximity to the piece of space debris, and gather images to assess the rocket body’s movement and the condition of the structure, Astroscale Japan said.

ADRAS-J Launch. Credit: Astroscale Japan, Inc.

The mission launched from New Zealand on February 18 and is part of Phase 1 of the Japan Aerospace Exploration Agency’s plan to deal with space debris. Shortly after launch, the ADRAS-J spacecraft began its maneuvers to rendezvous with the chosen piece of space debris. On April 9, mission engineers maneuvered the spacecraft to a desired position several hundred kilometers away from the rocket stage. Then, by April 16, the spacecraft was able to match the orbit of the rocket stage. By the next day, using  navigation inputs from the spacecraft’s suite of rendezvous payload sensors, ADRAS-J was able to attain close approach of several hundred meters.  

“The unprecedented image marks a crucial step towards understanding and addressing the challenges posed by space debris, driving progress toward a safer and more sustainable space environment,” Astroscale Japan said in a press release.

This particular rocket stage was chosen because it did not have any GPS data. Instead, the operations team had to rely on ground based observational data to approximate its position to make the approach. This provided a realistic target for testing debris analysis activity.

The next task, ADRAS-J will attempt to capture additional images of the upper stage through various controlled close approach operations. Astroscale Japan said the images and data collected are expected to be crucial in better understanding the debris and providing critical information for future removal efforts.

A future mission, ADRAS-J2, will also attempt to safely approach the same rocket body through RPO, obtain more images, then remove and deorbit the rocket body using in-house robotic arm technologies.

The post This is an Actual Picture of Space Debris appeared first on Universe Today.

Few space images are as iconic as those of the Horsehead Nebula. Its shape makes it instantly recognizable. Over the decades, a number of telescopes have captured its image, turning it into a sort of test case for a telescope’s power.

The JWST has them all beat.

The Horsehead Nebula is about 1300 light-years away in Orion. It’s part of the much larger Orion Molecular Cloud Complex. Horsehead is visible near the three stars in Orion’s Belt in a zoomed-in image.

The Horsehead Nebula is visible in this image of Orion’s Belt. It’s in the lower left, extending horizontally, to the lower left of the belt star Alnitak. Image Credit: By Davide De Martin (http://www.skyfactory.org); Credit: Digitized Sky Survey, ESA/ESO/NASA FITS Liberator – https://www.spacetelescope.org/projects/fits_liberator/fitsimages/davidedemartin_12/ (direct link), Public Domain, https://commons.wikimedia.org/w/index.php?curid=1329999

The leading image shows JWST’s view of the Horsehead Nebula alongside two other views. The Euclid image was captured in November 2023. Euclid features a wide-angle, 600-megapixel camera, and its primary job is to measure the redshift of galaxies and the Universe’s expansion due to dark energy. It took Euclid about one hour to capture the image, showcasing the telescope’s ability to gather highly detailed images quickly.

The Hubble captured its image in 2013 and was released as the telescope’s 23rd-anniversary featured image. The venerable Hubble does a good job of revealing structures hidden by dust. There’s nothing left to say about the Hubble that hasn’t been said already. It’s the revered elder among telescopes, and if you feel no reverence towards it, its contribution to science, and the people responsible for it, you may have a bad case of ennui.

The third image is a new one from the JWST’s NIRCam instrument. It’s described as the sharpest image of the Horsehead ever taken. It shows a small part of the iconic nebula in detail we don’t usually see. The JWST is so powerful it even shows background galaxies.

A zoom-in of the JWST image. The detail is incredible. Image Credit: ESA/Webb, CSA, K. Misselt, M. Zamani (ESA/Webb)

The Horsehead Nebula is the result of stellar erosion. The nebula itself was formed by a collapsing cloud of material, and a nearby hot star called Sigma Orionis illuminates the structure. The nebula is denser than its surrounding gas and has resisted the dissipative energy of the star, while the gas that used to surround it is long gone.

This definitely isn’t the last we’ll see of Horsehead. New, powerful telescopes coming online soon, like the Giant Magellan Telescope and the European Extremely Large Telescope will likely take a crack at the nebula. Prepare to be wowed.

There’s no rush. According to astronomers, the Horsehead Nebula will eventually be eroded away, too, but not for another five million years or so.

The post Insanely Detailed Webb Image of the Horsehead Nebula appeared first on Universe Today.

It stands to reason that stars formed from the same cloud of material will have the same metallicity. That fact underpins some avenues of astronomical research, like the search for the Sun’s siblings. But for some binary stars, it’s not always true. Their composition can be different despite forming from the same reservoir of material, and the difference extends to their planetary systems.

New research shows that the differences can be traced back to their earliest stages of formation.

Binary stars are the norm, while solitary stars like our Sun are in the minority. Some estimates place the number of binary stars in the Milky Way at up to 85%. These pairs of stars form from the same giant molecular clouds. Each cloud has a certain abundance of metals, and that abundance should be reflected in the stars themselves.

But that’s not always the case.

Sometimes, the metallicity of a pair of binary stars doesn’t agree. Astrophysicists have proposed three explanations for this.

Two explanations involve events occurring later in a star’s life after they’ve left the main sequence. One is atomic diffusion, where chemical elements settle into gradient layers in the star. The layers are determined by a star’s gravity and temperature. The second one involves a nearby planet. As stars age, expand, and become red giants, they engulf nearby planets. The planet would introduce new chemistry into the star, differentiating it from its binary partner.

As stars like our Sun age and leave the main sequence, they expand and become red giants, engulfing nearby planets. That can change the chemistry of the stars. Image Credit: fsgregs Creative Commons Attribution-Share Alike 3.0 Unported

The third explanation reaches back in time to the binary pair’s formation. This explanation says that the giant molecular cloud that spawned the stars wasn’t homogeneous. Instead, there were regional differences in the cloud’s chemistry, and stars formed in different locations showed noticeable differences in their chemical makeup.

A team of researchers wanted to dig into this third explanation to test its veracity. They used the Gemini South Telescope and its Gemini High-Resolution Optical SpecTrograph (GHOST) to examine the light from a pair of giant binary stars. The observations revealed significant differences in their spectra.

Sunset over Gemini South, on the summit of Mauna Kea in Hawai’i. Credit: Gemini

They presented their results in a paper titled “Disentangling the origin of chemical differences using GHOST.” It’s published in the journal Astronomy and Astrophysics. The lead author is Carlos Saffe of the Institute of Astronomical, Earth and Space Sciences (ICATE-CONICET) in Argentina. The researchers examined a pair of giant binary stars called HD 138202 + CD?30 12303.

The three explanations for chemical differences between binary stars all stem from studies of main sequence stars. The main sequence is where stars spend most of their time, reliably fusing hydrogen into helium for billions of years.

But Saffe and his colleagues took a different approach. They used Gemini and GHOST to examine a pair of binary stars that had left the main sequence behind and become giant stars. These stars are different from main sequence stars.

“GHOST’s extremely high-quality spectra offered unprecedented resolution,” said Saffe, “allowing us to measure the stars’ stellar parameters and chemical abundances with the highest possible precision.”

This table from the research shows some of the differences between the pair of giant binary stars. The third column shows their different metallicities, expressed by the Fe/H (iron hydrogen) ratio. The Star A is more metal-rich by ?0.08 dex than its companion. Image Credit: Saffe et al. 2024.

These stars experience dredge-ups. Dredge-ups are when a star’s convection zone extends from the surface all the way down to where fusion is taking place. They’re powerful convective currents that mix fusion products into the star’s surface layer when a main sequence star becomes a red giant.

This diagram of the Sun helps explain dredge-ups. The Sun is still on the main sequence, so its convective region is on its surface. But when stars like the Sun become red giants, temporary convective cells called dredge-ups can reach from the surface all the way to the fusion core. This can introduce different chemical elements onto the visible surface. Image Credit: CSIRO/ATNF/Naval Research Laboratory

However, the researchers say that dredge-ups and the atomic diffusion they drive can’t explain the wide difference between stars.

The convection currents would also rule out the second proposed explanation: planetary engulfment. With such strong currents, the chemicals from an engulfed planet would quickly be diluted. “Giant stars are thought to be significantly less sensitive than main-sequence stars to engulfment events,” the authors write.

The authors went further and calculated the amount of planetary material a giant star would need to digest to cause the difference in metallicity between the stars. “We estimate that star A would need to have ingested between 11.0 and 150.0 Jupiter masses of planetary material, depending on the adopted convective envelope mass and metallic content of the ingested planet,” the authors explain. That’s an awful lot of material. They also explain that the planets must have had extremely high metallicity for the low value of 11 Jupiter masses to cause the chemical differences.

That only leaves one explanation: inhomogeneities in the molecular cloud.

This is a two-panel mosaic of part of the Taurus Giant Molecular Cloud, the nearest active star-forming region to Earth. The darkest regions are where stars are being born. Research shows that small inhomogeneities in the cloud can produce binary stars with different metallicities. Image Credit: Adam Block /Steward Observatory/University of Arizona

“This is the first time astronomers have been able to confirm that differences between binary stars begin at the earliest stages of their formation,” said Saffe.

“Using the precision-measurement capabilities provided by the GHOST instrument, Gemini South is now collecting observations of stars at the end of their lives to reveal the environment in which they were born,” said Martin Still, NSF program director for the International Gemini Observatory. “This gives us the ability to explore how the conditions in which stars form can influence their entire existence over millions or billions of years.”

The results go a long way to explaining why a pair of binary stars can have differing compositions. But they reach even further than that. They also explain why a pair of binary stars can have such different planetary systems. “Different planetary systems could mean very different planets — rocky, Earth-like, ice giants, gas giants — that orbit their host stars at different distances and where the potential to support life might be very different,” said Saffe.

But the results also present a challenge. Astronomers use chemical tagging to identify stars that are associated with one another. Stars from the same stellar nursery are expected to have similar compositions. But that method seems unreliable in light of these findings.

The results also challenge the idea that differences in composition between binary stars can be explained by planet engulfment. Instead, those differences might stem from the stars’ earliest days of formation.

“By showing for the first time that primordial differences really are present and responsible for differences between twin stars, we show that star and planet formation could be more complex than initially thought,” said Saffe. “The Universe loves diversity!”

This artist’s concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. If differences in chemical compositions in stars stem from their earliest days of formation, then those differences must affect the types of planets that form around them. (Image by NASA/JPL-Caltech.)

The only drawback of this study is the sample size of one. Small sample sizes are always cautionary: they can lead to an eventual conclusion but don’t form reliable conclusions independently. The authors know this.

“We strongly encourage the study of giant-giant pairs,” the researchers conclude. “This novel approach might help us to distinguish the origin of the slight chemical differences observed in multiple systems.”

The post Binary Stars Form in the Same Nebula But Aren’t Identical. Now We Know Why. appeared first on Universe Today.

We go about our daily lives sheltered under an invisible magnetic field generated deep inside Earth. It forms the magnetosphere, a region dominated by the magnetic field. Without that planetary protection shield, we’d experience harmful cosmic radiation and charged particles from the Sun.

Has Earth always had this deflector shield? Probably so, and the evidence is in old rocks. A team of researchers at University of Oxford and MIT found the earliest evidence for its existence in stones found along the coast of Greenland in a region called the Isua Supercrustal Belt.

Geologists have long known that iron particles in rocks “entrain” a print of the magnetic field that was in place when they formed. So, the research team uncovered rocks that formed some 3.7 billion years ago. It’s not an easy task, according to team lead Claire Nichols of the Department of Earth Sciences at Oxford. “Extracting reliable records from rocks this old is extremely challenging,” Nichols pointed out. “It was really exciting to see primary magnetic signals begin to emerge when we analyzed these samples in the lab. This is a really important step forward as we try and determine the role of the ancient magnetic field when life on Earth was first emerging.”

This 3.7-billion-year-old rock from Greenland. Entrained magnetic field fingerprints help scientists determine that our magnetosphere and magnetic field existed when this rock formed. Courtesy: Claire Nichols.

The team’s samples recorded a magnetic field strength of 15 microteslas at the time they formed. Today, Earth’s field strength is closer to 30 microteslas, so it’s obvious that our magnetic field and magnetosphere have been there for billions of years. It’s also clear that the field changes over time. The science team also found that early Earth’s magnetosphere was amazingly similar to the one it has today.

Tracking Earth’s Magnetosphere through Time

Our planet has a main dynamo at its heart. There are two cores—an inner one and an outer one. Motions in the core regions generate the magnetic field that defines our magnetosphere. Molten iron mixes and moves in the fluid outer core and the inner core solidifies. The two actions together create that dynamo. That’s what’s happening inside our planet today.

This cutaway of planet Earth shows the familiar exterior of air, water and land as well as the interior: from the mantle down to the outer and inner cores. Currents in hot, liquid iron-nickel in the outer core create our planet’s protective but fluctuating magnetic field and magnetosphere. Credit: Kelvinsong / Wikipedia

However, when Earth was first forming some 4.5 billion years ago, that solid inner core didn’t exist. Without the interaction we see today between the two parts of the core, it’s hard to know how any early magnetic field existed. That’s an open question among geologists and planetary scientists: how did it form and how was it sustained?

Another question relates to how much the planetary magnetic field has varied over time. Answering that one would help geologists understand just when the solid inner core formed. It would also show how much heat has escaped our planet from deep inside over time. Heat escape drives plate tectonics, which uses large “plates” of rock to shift things around on the surface over hundreds of millions of years.

What Do the Rocks Tell Us?

Rocks have a long and complex history. They form as a molten mixture that solidifies, or in the case of sandstones, are laid down in layers that then harden. In the case of molten rocks, they have magnetic field fingerprints entrained at the time of formation. In measuring those fingerprints, geologists account for any heating that could “reset” the magnetic signatures over time. The Greenland rocks are relatively pristine, meaning they haven’t been significantly heated since they formed. That means their magnetic fingerprints haven’t changed since formation.

Lava cooling after an eruption. This rock has an entrained magnetic field fingerprint from the time it formed. Credit: kalapanaculturaltours.com

Rocks also get weathered by wind, temperature changes and erosion, but the Isuan samples seem to be relatively pristine, according to Benjamin Weiss of MIT. “Northern Isua has the oldest known well-preserved rocks on Earth,” Weiss said. “Not only have they not been significantly heated since 3.7 billion years ago but they have also been scraped clean by the Greenland ice sheet.”

Rocks Through Time

The rocks the team studied date back to the Archean Eon—the second-oldest geologic eon in Earth’s history. That period began about 4 billion years ago, and during that time Earth was largely an ocean world with a limited amount of continental surface. Since then, Earth’s surface has changed a great deal, destroying or burying rocks from earlier times. So, finding rocks that date back that far in time is a big deal.

The Isuan rocks are relatively unchanged since they formed, and bear proof of a magnetic field existing less than a billion years after the planet formed. That same early magnetic field could have played a role in the development of our planet’s atmosphere, by assisting in removing xenon gas. Other old rocks may well tell scientists more about the birth of the magnetic field. There are rocks in Canada, Australia and South Africa that could give unique insight into the formation of the field and its role in making Earth habitable for life.

For More Information

Researchers Find Oldest Undisputed Evidence of Earth’s Magnetic Field
Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal Belt, Southern West Greenland

The post Earth Had a Magnetosphere 3.7 Billion Years Ago appeared first on Universe Today.

When the first stars in the Universe formed, the only material available was primordial hydrogen and helium from the Big Bang. Astronomers call these original stars Population Three stars, and they were extremely massive, luminous, and hot stars. They’re gone now, and in fact, their existence is hypothetical.

But if they did exist, they should’ve left their fingerprints on nearby gas, and astrophysicists are looking for it.

The hunt for the Universe’s Population 3 (Pop III) stars is important in astrophysics. They were the first to form astronomical metals, elements heavier than hydrogen and helium. Only once these metals were available could rocky planets form. Their metals also fed into the next generation of stars, leading to the higher metallicity we observe in stars like our Sun.

Since Pop III stars were so massive and hot, they didn’t last long. None would have survived to this day. But the powerful JWST can expand the search for these crucial stars by looking back in time for their ancient light. That’s what the JWST-JADES (James Webb Space Telescope Advanced Deep Extragalactic Survey) is all about.

Researchers working with JADES data have found tantalizing evidence of Pop III stars in GN-z11, a high-redshift galaxy that’s one of the furthest galaxies from Earth ever observed. Their findings are in the paper “JWST-JADES. Possible Population III signatures at z=10.6 in the halo of GN-z11.” The lead author is Roberto Maiolino, a professor of Experimental Astrophysics at the Cavendish Laboratory (Department of Physics) and the Kavli Institute for Cosmology at the University of Cambridge. The research will be published in the journal Astronomy and Astrophysics.

“Finding the first generation of stars formed out of pristine gas in the early Universe, known as Population III (Pop III) stars, is one of the most important goals of modern astrophysics,” Maiolino and his colleagues write in their paper. “Recent models have suggested that Pop III stars may form in pockets of pristine gas in the halo of more evolved galaxies.”

GN-z11 is one such galaxy. At a redshift of z = 10.6034, the JWST sees the galaxy as it existed about 13.4 billion years ago, corresponding to about 400 million years after the Big Bang.

Pop III stars were massive and could be as much as 1000 times more massive than the Sun. These massive stars would’ve been exceptionally hot, which can provide a clue to their presence. Astrophysicists think all that heat could’ve doubly ionized nearby helium. So they search for the expected signature of that helium: prominent HeII nebular lines called the HeII?1640 emission line. To indicate the presence of Pop III stars, the HeII lines need to be unaccompanied by any metal lines.

The JWST observed the galaxy with its NIRSpec-IFU (Integrated Field Unit) and found a tentative detection of HeII?1640.

This figure from the research shows the detection of doubly-ionized Helium at 1.903 µm. in the galaxy GN-z11. Image Credit: Maiolino et al. 2024.

Detecting the doubly-ionized helium line was only the first step. Pop III stars aren’t the only objects that could’ve ionized the helium. To determine if the ancient stars were responsible, the researchers examined the galaxy and isolated several features.

Along with the HeII?1640, they also found Lyman-alpha emissions and CIII, or doubly-ionized carbon.

This figure from the research shows the detection of different emissions. The red star in the top images indicates the position of the continuum of GN-z11. The bottom row shows the lines mapped onto a JWST NIRCam image. The ‘fewer exposures’ on the top row indicates a lack of exposures in the upper portions of the panels due to a telescope-pointing error. Image Credit: Maiolino et al. 2024.

In the images above, the researchers note several features that are clues to the source of the helium ionization.

The HeII emissions show a plume extending to the west of GN-z11. It could be tracing gas photoionized by the galaxy’s active galactic nucleus (AGN.) Since CIII is so weak there, it could indicate very low metallicity gas photoionized by the AGN.

The image also shows a clump of HeII to the northeast of GN-z11. The researchers call this clump the “most intriguing” feature found. They analyzed the clump in the image below.

This figure from the research shows the spectra of the HeII clump. The observed emissions (blue) line up with the expected emissions from a galaxy at redshift z=10.600. Image Credit: Maiolino et al. 2024.

So what does this all add up to? Did the researchers find Pop III stars?

The spectral feature in the clump is strong evidence of photoionization by Pop III stars, according to the authors. “This wavelength corresponds to HeII?1640 at z=10.600, and it is fully consistent with the redshift of GN-z11,” they write. The same emission was detected over a larger area to the northeast, possibly with a second, fainter clump.

The authors say that the AGN could’ve photoionized the helium close to the galaxy’s center, but it can’t explain the HeII further away. Pop III stars are the best explanation, according to the authors.

Other evidence for Pop III stars comes from the emissions widths of the HeII lines. The high width suggests photoionization by metal poor Pop III stars rather than by Pop II stars with higher metallicity.

The extent of the ionization also indicates a certain mass for the Pop III stars, and the indicated mass agrees with simulations.

There’s another possibility: a direct collapse black hole (DCBH). “We also considered the alternative possibility of photoionization by a DCBH in the HeII clump,” the authors write. But the emission width should be lower in that scenario, although not by a lot. “Hence, this scenario remains another possible interpretation,” the authors write.

If future observations confirm the presence of Pop III stars in GN-z11, that’s a pretty big deal. But even if we have to wait for that confirmation, this research shows how powerful the JWST is again.

“These results have demonstrated the JWST’s capability to explore the primitive environment around galaxies in the early Universe, revealing fascinating properties,” the researchers conclude.

The post Astronomers Think They’ve Found Examples of the First Stars in the Universe appeared first on Universe Today.

On 9 January 2024, the Einstein probe was launched, its mission to study the night sky in X-rays. The first image from the probe that explores the Universe in these energetic wavelengths has just been released. It shows Puppis A, the supernova remnant from a massive star that exploded 4,000 years ago. The image showed the expanding cloud of ejecta from the explosion but now, Einstein will continue to scan the skies for other X-ray events. 

The Chinese and European probe was designed to revolutionise our understanding of the Universe in X-rays. Named after none other than Albert Einstein, it houses cutting edge technology that will enable the observation of black holes, neutron stars and other events and phenomena emitting X-ray radiation. To achieve this it has two science instruments on board; the Wide-field X-ray Telescope (WXT) to give large field views of the sky and the Follow-up X-ray Telescope (FXT) which homes in on objects of interest identified by WXT.

The Einstein probe has three main questions it hopes to address focusing on black holes, gravity waves and supernovae. The recent image just released shows the stunning Puppis A supernova remnant. Supernova are a common process that takes place at the end of a massive star’s life. A star like the Sun is fusing hydrogen in its core into helium. The process is known as thermonuclear fusion and it releases heat, light and an outward pressure known as the thermonuclear force. While a star is stable, the thermonuclear force balances the force of gravity which is trying to collapse the star. 

Massive stars will continue fusing different elements in the core until an iron core remains. It’s not possible to fuse iron so the thermonuclear force ceases allowing gravity to win. the core collapses and the inward rushing material crashes down onto the core and rebounds into a massive explosion known as a supernova. 

Puppis A is one such object that is thought to have exploded 4,000 years ago. It lies about 7,000 light years from us which means the light that the radiation detected by the Einstein probe left about 7,000 years ago. 

In the image released from Einstein, the cloud like structure is all that remains of the star that went supernova. It is possible to see a bright dot at the centre of the cloud, this is the core of the star that remains, a neutron star. The FXT image was accompanied by a spectrum to show the distribution of energy to help understand the elements present. 

Source : Supernova remnant Puppis A imaged by Einstein Probe

The post First Light from Einstein Probe: A Supernova Remnant appeared first on Universe Today.

Anyone familiar with astronomy will know that galaxies come in a fairly limited range of shapes, typically; spiral, elliptical, barred-spiral and irregular. The barred-spiral galaxy has been known to be a feature of the modern universe but a study from astronomers using the Hubble Space Telescope has recently challenged that view. Following on observations using the James Webb Space Telescope has found the bar feature in some spiral galaxies as early as 11 billion years ago suggesting galaxies evolved faster in the early Universe than previously expected. 

Our own Galaxy, the Milky Way is a spiral galaxy with a central nucleus and spiral arms emanating out from the centre. Our Solar System lies about 25,000 light years from the centre. Look at the galaxies in the sky though and you will see a real mix but generally they fall under the four main categories. Edwin Hubble tried to bring some structure to the different shapes by developing his galaxy classification scheme to articulate not only the shape but also the sub categories within them. 

This research published in Nature is the first direct confirmation that supermassive black holes are capable of shutting down galaxies

It has been known for some time that galaxies aren’t static. They move and they evolve and change. Spiral galaxies for example, as they age, they often develop a bar feature. The bar joins up the spiral arms instead of a nucleus connecting them and it is believed they are temporary, forming when a build of gas creates a burst of star formation. 

The existence of a bar in a spiral galaxy suggests that the galaxy is fairly stable. Understanding just how the bar feature forms is key to understanding the evolutionary process of the galaxy itself. All previous observations showed that the appearance of the bar significantly reduces from the nearby Universe to redshifts near a value of one. This tells us that the bar seemed to be a modern feature and not present in the early Universe. 

The barred spiral galaxy NGC 1300. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

In a new paper by lead author Zoe A Le Conte, observations from the more sensitive James Webb Space Telescope report that galaxies to greater redshift are studied for bar features. Data is used from the Cosmic Evolution Early Release Science Survey and the observations from the Public Release Imaging for Extragalactic Research studies. Only the galaxies that also appear in the Cosmic Assembly Near Infra Red Deep Extragalactic Legacy Survey are used giving a sample of 368 face on galaxies. 

The team visually searched through the 368 galaxy selection to classify and identify those with bars between redshifts 1 and 2 and then repeated the exercise for those between redshift 2 and 3. As expected, the fraction of bars reduced from around 17.8% between a red shift of 1 and 2 down to 13.8% at the greater red shift of 2 to 3. 

The study revealed that JWST’s infra-red sensitivity picked up twice as many barred-spiral galaxies than the HST’s more blue sensitive imaging platform. Le Conte and her team conclude that the evolution of bars in spiral galaxies began to appear at a much earlier epoch, around 11 billion years ago. 

Source : A JWST investigation into the bar fraction at redshifts 1 ? z ? 3

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When a spacecraft arrives at its destination, it settles into an orbit for science operations. But after the primary mission is complete, there might be other interesting orbits where scientists would like to explore. Maneuvering to a different orbit requires fuel, limiting a spacecraft’s number of maneuvers.

Researchers have discovered that some orbital paths allow for no-fuel orbital changes. But the figuring out these paths also are computationally expensive. Knot theory has been shown to find these pathways more easily, allowing the most fuel-efficient routes to be plotted. This is similar to how our GPS mapping software plots the most efficient routes for us here on Earth.

In mathematics, knot theory is the study of closed curves in three dimensions. Think of it as looking at a knotted necklace or a tangle of fishing line, and figuring out how to untangle them in the most efficient manner.

In the same way, a spacecraft’s path could be computed in a crowded planetary system – around Jupiter and all its moons, for example – where the best, simplest and least tangled route could be computed mathematically.

A graphic showing the orbital path the Danuri Lunar Pathfinder spacecraft will take to go into orbit around the Moon. Credit: Korea Aerospace Research Institute (KARI)

According to a new paper in the journal Astrodynamics, “Applications of knot theory to the detection of heteroclinic connections between quasi-periodic orbits,” using knot theory to untangle complicated spacecraft routes would decrease the amount of computer power or just plain guesswork in plotting out changes in spacecraft orbits.

“Previously, when the likes of NASA wanted to plot a route, their calculations relied on either brute force or guesswork,” said Danny Owen, a postgraduate research student in astrodynamics, in a press release from the University of Surrey. “Our new technique neatly reveals all possible routes a spacecraft could take from A to B, as long as both orbits share a common energy level.”

Owen added that this new process makes the task of planning missions much simpler. “We think of it as a tube [subway] map for space,” he said.

Spacecraft navigation is complicated by the fact that nothing in space is a fixed position. Navigators must meet the challenges of calculating the exact speeds and orientations of a rotating Earth, a rotating target destination, as well as a moving spacecraft, while all are simultaneously traveling in their own orbits around the Sun.

Since fuel is a limited resource for most missions, it would be beneficial to require the least amount of fuel possible in making any changes to the course of a spacecraft in orbit.  

Spacecraft navigators use something called heteroclinic orbits — often called heteroclinic connections — which are paths that allow a spacecraft to travel from one orbit to another using the most efficient amount of fuel – or sometimes no fuel at all. But this usually takes a large amount of computer power or a lot of time to figure out.  

Artist’s impession of the Lunar Gateway with the Orion spacecraft docked on the left side. Credit: ESA

But Owen and co-author Nicola Baresi, a lecturer in Orbital Mechanics at the University of Surrey, wrote that by using knot theory, they have developed “a method of robustly detecting heteroclinic connections,” they wrote in their paper, to quickly generate rough trajectories – which can then be refined. This gives spacecraft navigators a full list of all possible routes from a designated orbit, and the one that best fits the mission can be chosen. They can then choose the one that best suits their mission.

The researchers tested their technique on various planetary systems, including the Moon, and the Galilean moons of Jupiter.

“Spurred on by NASA’s Artemis program, the new Moon race is inspiring mission designers around the world to research fuel-efficient routes that can better and more efficiently explore the vicinity of the Moon,” said Baresi. “Not only does our technique make that cumbersome task more straightforward, but it can also be applied to other planetary systems, such as the icy moons of Saturn and Jupiter.”

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The list of chemicals found in space is growing longer and longer. Astronomers have found amino acids and other building blocks of life on comets, asteroids, and even floating freely in space. Now, researchers have found another complex chemical to add to the list.

The new chemical is known as 2-methoxyethanol (CH3OCH2CH2OH). It’s one of several methoxy molecules that scientists have found in space. But with 13 atoms, it’s one of the largest and most complex ones ever detected.

A team of scientists called the McGuire Group specializes in detecting chemicals in space. The McGuire Group and other researchers from institutions in Florida and France worked together to find 2-methoxyethanol.

The researchers published their findings in The Astrophysical Journal Letters. It’s titled “Rotational Spectrum and First Interstellar Detection of 2-methoxyethanol Using ALMA Observations of NGC 6334I.” The lead author is Zachary Fried, a graduate student in the McGuire Group at MIT.

A ball and stick model of 2-methoxyethanol (CH3OCH2CH2OH). With 13 atoms, it’s one of the largest complex chemicals ever found in space. Image Credit: By Ben Mills – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3081683

“There are a number of ‘methoxy’ molecules in space, like dimethyl ether, methoxymethanol, ethyl methyl ether, and methyl formate, but 2-methoxyethanol would be the largest and most complex ever seen,” said lead author Fried.

The researchers didn’t stumble upon the large molecule. It was found as part of a concerted effort to detect new chemicals in space. It all started with machine learning. In 2023, one machine-learning model suggested they look for 2-methoxyethanol. The next step was the lab, where researchers performed experiments that measured and analyzed the molecule’s rotational spectrum here on Earth.

“We do this by looking at the rotational spectra of molecules, the unique patterns of light they give off as they tumble end-over-end in space,” said Fried. “These patterns are fingerprints (barcodes) for molecules. To detect new molecules in space, we first must have an idea of what molecule we want to look for, then we can record its spectrum in the lab here on Earth, and then finally we look for that spectrum in space using telescopes.”

The researchers measured the molecule’s spectrum over a broadband region of frequencies ranging from the microwave to sub-millimetre wave regimes (from about 8 to 500 gigahertz).

With that data in hand, the researchers turned to ALMA, the Atacama Large Millimetre/sub-millimetre Array. ALMA gathered data from two star-forming regions: NGC 6334I and IRAS 16293-2422B. Researchers from the McGuire Group, the National Radio Astronomy Observatory, and the University of Copenhagen all worked on analyzing ALMA’s observations.

“Ultimately, we observed 25 rotational lines of 2-methoxyethanol that lined up with the molecular signal observed toward NGC 6334I (the barcode matched!), thus resulting in a secure detection of 2-methoxyethanol in this source,” said Fried. “This allowed us to then derive physical parameters of the molecule toward NGC 6334I, such as its abundance and excitation temperature. It also enabled an investigation of the possible chemical formation pathways from known interstellar precursors.”

NGC 6334m the Cat’s Paw Nebula. Image Credit: ESO

Here on Earth, 2-methoxyethanol is used mostly as a solvent. It’s toxic to bone marrow and testicles. But its status here on Earth isn’t relevant to its discovery.

The large molecule isn’t a building block for life, either. It’s significant because of its size and complexity. Scientists are interested in understanding how chemistry evolves and forms large molecules in regions where stars and planets are forming.

“Our group tries to understand what molecules are present in regions of space where stars and solar systems will eventually take shape,” explained Fried. “This allows us to piece together how chemistry evolves alongside the process of star and planet formation.”

Molecular complexity is the hallmark of life, so, of course, scientists want to understand molecular complexity in space. As of 2021, scientists only found six molecules in space larger than 13 atoms outside our Solar System. McGuire’s team found many of them.

Finding them is the first step. The next step is to figure out how and where they form. Though there are no direct links between 2-methoxyethanol and life, all complex chemistry has something to tell us about complex chemistry in general.

“Continued observations of large molecules and subsequent derivations of their abundances allows us to advance our knowledge of how efficiently large molecules can form and by which specific reactions they may be produced,” said Fried. “Additionally, since we detected this molecule in NGC 6334I but not in IRAS 16293-2422B, we were presented with a unique opportunity to look into how the differing physical conditions of these two sources may be affecting the chemistry that can occur.”

IRAS 16293?2422 in the star-forming region Rho Ophiuchi. Image Credit: ESO

NGC 6334I is a higher-mass star-forming region compared to IRAS 16293-2422B. That means it could have a potentially enhanced radiation field. That enhanced radiation could produce more precursors for 2-methoxyethanol, eventually leading to more of the molecule itself. Warmer dust temperatures may have contributed, too. Warmer dust allows greater dust mobility, leading to chemical fragments being allowed to recombine.

Thanks to ever-improving observational tools and methods, including machine learning, astrochemistry is a blossoming field. If we’re ever going to understand how life on Earth arose and where it may likely rise elsewhere in the galaxy, astrochemistry will play a leading role. Though 2-methoxyethanol isn’t directly related to life, its detection still tells scientists something.

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The JWST is flexing its muscles with its interferometry mode. Researchers used it to study a well-known extrasolar system called PDS 70. The goal? To test the interferometry mode and see how it performs when observing a complex target.

The mode uses the telescope’s NIRISS (Near Infrared Imager and Slitless Spectrograph) as an interferometer. It’s called Aperture Masking Interferometry (AMI) and it allows the JWST to reach its highest level of spatial resolution.

A team of astronomers used the JWST’s AMI to observe the PDS 70 system. PDS 70 is a young T-Tauri star about 5.4 million years old. At that young age, its protoplanetary disk still surrounds it. PDS 70 is a well-studied system that’s caught the attention of astronomers. It’s unique because its two planets, PDS 70 b and c, make it the only multiplanet protoplanetary disk system we know of.

The researchers wanted to determine how easily the AMI would find PDS 70’s two known planets and what else it could observe in the system.

Their research is “The James Webb Interferometer: Space-based interferometric detections of PDS 70 b and c at 4.8 µm.” It’s available on the pre-print site arxiv.org and hasn’t been peer-reviewed yet. The lead author is Dori Blakely from the Department of Physics and Astronomy at the University of Victoria, BC, Canada.

PDS 70 is known for its pair of planets. PDS 70 b is about 3.2 Jupiter masses and follows a 123-year orbital period. PDS 70 c is about 7.5 Jupiter masses and follows a 191-year orbit. One of the most puzzling things about the system is that PDS 70 b appears to have its own accretion disk. The system also shows intriguing evidence of a third body, maybe another star.

The JWST’s interferometry easily detected both planets. In fact, the observations found evidence of circumplanetary disk emissions around PDS 70 b and c. “Our photometry of both PDS 70 b and c provide evidence for circumplanetary disk emission,” the researchers write. That means we can see the star and its protoplanetary disk, where planets form, and the individual circumplanetary disks around each planet. Those disks are where moons form, and seeing them in a system 366 light-years away is very impressive.

The PDS 70 system as seen by the JWST’s interferometry mode and after extensive data processing. A yellow star marks the location of PDS 70, with PDS 70 b and c also shown. The JWST shows the infrared emissions coming from the disk. Image Credit: Blakely et al. 2024.

The JWST’s AMI observations also found a third point source. Its light is different from the light from the pair of planets and more similar to the light from the star. If it’s another planet, its composition is different from the others. If it’s not another planet, that doesn’t mean it necessarily has to be another star. The JWST could be seeing scattered starlight from another gaseous, dusty structure or clump in the disk. “This indicates that what we observe is not due to a simple inner disk structure, and may hint at a complex inner disk morphology such as a spiral or clumpy features,” the researchers explain.

The unexplained third source could be something more exotic. Previous research also identified the source and suggested that it could be an accretion stream flowing between PDS 70 b and c. “We interpret its signal in the direct vicinity of planet c as tracing the accretion stream feeding its circumplanetary disk,” the authors of the previous research wrote.

These images are from previous research that used the JWST but not its interferometry mode. The top row is from the telescope’s F187N filter, and the bottom row is from the telescope’s F480M filter. The left column shows the complete images. The middle column shows the system with the disk subtracted. The right column shows the system with the disk and both known planets extracted. What remains is a potential third planet, planet “d,” and an arm-like feature and potential accretion stream. Image Credit: V. Christiaens et al. 2024.

Or, perhaps most exciting, the source could be another planet. “Another scenario is that the signal we observe is due to an additional planet interior to the orbit of PDS 70 b,” the authors explain. “Follow-up observations will be needed to determine the nature of this emission,” the authors write.

Part of the observations’ success comes from what it didn’t detect. Protoplanetary disks are dusty and difficult to examine. The JWST has a leg up on it because it can see infrared light. When used in interferometry mode, it’s a powerful tool. The fact that it failed to detect any other planets is progress, though. “Additionally, we place the deepest constraints on additional planets,” in part of the disk. These constraints will help future researchers examine the PDS 70 system and other extrasolar systems.

The results also show another of AMI’s strengths: its ability to see into parts of the parameter space that other telescopes can’t. “Furthermore, our results show that NIRISS/AMI can reliably measure relative astrometry and contrasts of young planets in a part of parameter space (small separations and moderate to high contrasts) that is unique to this observing mode, and inaccessible to all other present facilities at 4.8 µm,” the authors explain.

The JWST has already established its place in the history of astronomy. It’s delivered on its promise and has already significantly contributed to our understanding of the cosmos. The telescope’s observations with its Aperture Masking Interferometry mode will further cement its place in history.

“Here, using the power of the James Webb Interferometer, we detect PDS 70, its outer disk, and its two protoplanets, b and c. These are the first planets detected with space-based interferometry,” the authors write.

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Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with surface temperatures similar to Jupiter. The largest brown dwarfs have surface temperatures around 3,000 K and look essentially like stars.

Because of this, it can be difficult to study brown dwarfs, particularly ones that don’t orbit other stars. Without much reflected or emitted light, we can’t easily analyze their spectra to determine their composition. Fortunately, some brown dwarfs do emit radio light thanks to their strong magnetic fields.

Planets such as Earth and Jupiter have strong magnetic fields, and this means they can trap ionized particles such as hydrogen. These charged particles then spiral along the magnetic field lines until they collide with the planet’s upper atmosphere, generating glowing aurora. On Earth, we see them as the Northern Lights. For brown dwarfs, we can’t see the visible light of their aurora, but we can detect their radio glow.

Recently a team looked at the auroral light from a brown dwarf known as W1935. It is a cold brown dwarf 47 light-years from Earth with a surface temperature of just 200 °C. Within the spectra the team found light emissions from methane. While the presence of methane was expected in cold brown dwarfs, the fact that the methane emitted light was not. This means the atmosphere of W1935 likely has a thermal inversion, where the upper atmosphere is warmer than the lower layers.

This is true for the atmosphere of Earth but is driven by solar radiance. W1935 doesn’t orbit a star, so how can its upper atmosphere get so warm? One possible explanation is that the brown dwarf has an undetected small companion. This companion could be ejecting material similar to the way Saturn’s moon Enceleadus ejects water vapor. Once ionized in the vacuum of space, it would become trapped by the magnetic fields of W1935, eventually colliding with the brown dwarf’s upper atmosphere and giving it a bit of thermal heating.

This discovery shows that even the smallest brown dwarfs defy easy classification. Though they resemble planets, they may have their own planetary system like a star.

Reference: Faherty, Jacqueline K., et al. “Methane emission from a cool brown dwarf.” Nature 628.8008 (2024): 511-514.

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Life on Earth would not be possible without food, water, light, a breathable atmosphere and surprisingly, a magnetic field. Without it, Earth, and its inhabitants would be subjected to the harmful radiation from space making life here, impossible. If we find exoplanets with similar magnetospheres then those worlds may well be habitable. The Square Kilometer Array (SKA) which is still under construction should be able to detect such magnetospheres from radio emissions giving us real insight into our exoplanet cousins. 

The magnetic field of Earth is the result of churning motion of liquid iron and nickel in the outer core. The resultant magnetic field has properties of a giant magnet with a north pole and a south pole and it extends from the core outward, enveloping the entire planet.  The presence of the field stops harmful solar radiation and cosmic particles. Magnetic fields are not static though and it is not uncommon for them to flip, as has happened to our own magnetic field. 

Since we have been hunting exoplanets (and to date, over 5,000 have been discovered) it has become clear that there are a good number of super sized gas gas giants. As our detection technology and methods improve, smaller, more Earth like planets are starting to be discovered. It is therefore not unreasonable to think that, among them, there may well be alien planets with magnetic fields making them, therefore good candidates for habitable environments. 

Artist impression of glory on exoplanet WASP-76b. Credit: ESA

Understanding exoplanet magnetic fields is in its infancy. So far, we have only explored magnetic fields around the planets in our Solar System. What we do know is that any planetary magnetic field emits radio signals due to the Electron Cyclotron Maser Instability mechanism. Sounds like something out of StarTrek or StarWars depending on your preference but either way, electromagnetic radiation is amplified by electrons that are trapped in the field. It is this amplified radiation that can be detected remotely IF we have a radio telescope with the capability. 

A recent paper authored by Fatemeh Bagheri and team from the University of Texas explores whether it might be possible to detect the emissions using the Square Kilometre Array. The concept of the SKA is a radio interferometer with components in Australia and Africa and its headquarters in the UK. The international array of radio telescopes that are joined together electronically to operate as one collecting area of a square kilometre. It affords the ability to study the radio sky with higher sensitivity and resolution than ever before and it’s this, that Bagheri and team are focusing their attention. 

Aerial image of the South African MeerKAT radio telescope, part of the Square Kilometer Array (SKA). Credit: SKA

Using NASA’s exoplanet archive data, they calculated the strength of radio signal from 80 confirmed planets. They took the planet’s radius, mass and orbital distance from the host star, along with the stars’ mass, radius and distance form us to estimate the signal from the magnetosphere. The results were promising and suggest that, according to their analysis exoplanets; Qatar-4 b, TOI-1278 b, and WASP-173 A b would indeed emit radio signals from their magnetosphere that the SKA could detect. Unfortunately we will have to wait until 2028 when SKA is operational but already, it seems researchers are lining up to use it and this piece of research in particular looks set not only to herald a greater understanding of exoplanets but also the possibility of life in the Universe. 

Source : Exploring Radio Emissions from Confirmed Exoplanets Using SKA

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When I heard about this I felt an amused twinge of envy. Over the last year I have been using an unimpressive 4G broadband service and at best get 20 Mbps, NASA’s Psyche mission has STILL been getting 23 Mbps at 225 million km away! It’s all thanks to the prototype optical transmission system employed on the probe. It means it can get up to 100 times more data transmission rate than usual radio. 

NASA’s Pysche mission is on its way to explore the metal rich asteroid between the orbits of Mars and Jupiter called, not surprisingly Psyche. The intriguing thing about the asteroid is that it seems to be the iron rich core of an unformed planet. The spacecraft carried a wealth of scientific instruments to explore the asteroid including an imaging rig, gamma ray and neutron spectrometer, magnetometer and an X-band Gravity platform. 

It began its two year journey on 13 October with its destination, a tiny world that may help us unravel some of the mysteries of the formation of our Solar System. The theory that Psyche is a failed planetary core is not certain so this will be one of the first of its mission objectives; is it simply unmelted metal or was it a core. In order to understand this it’s necessary to work out its age. Secondary to the origin, other objectives are to explore the composition and its topography across the surface. 

Asteroid Psuche was discovered in March 1852 by Italian astronomer Annibale de Gasparis. Because he discovered it, he was allowed to name it and settled on Psyche after the Greek goddess of the soul. It orbits the Sun at a distance of between 378 million to 497 million kilometres and takes about 5 Earth years to complete an orbit. Shaped like a potato, or perhaps more accurately classed as ‘irregular’ it is actually a little ellipsoid in shape measuring 280 km across wide at its widest part and 232 km across long. 

Illustration of the metallic asteroid Psyche. Credit: Peter Rubin/NASA/JPL-Caltech/ASU

Of more interest than the objectives perhaps (although I for one am looking forward to learn more about this wonderful asteroid) was the trial communication system. The newly developed Deep Space Optical Communications technology (DSOC) is not the primary communications platform but it is there as a prototype. 

The optical system which relies upon laser technology successfully sent back engineering data at a distance of 226 million kilometres. Perhaps more impressively though, the spacecraft has shown that it can transmit at a rate of 267 Mbps (YES you read that right, just over quarter of a Gbps!) The impressive download speed was achieved on 11 December last year when a 15 second ultra high definition video was sent to Earth. Sadly though, as the spacecraft recedes, its data transmission capability will reduce. Still far better than normal radio communications though. 

Using a powerful modulated laser, the Optical Communication Telescope Laboratory in California will be able to send data at a low rate to Psyche. To receive data, a photon counting receiver has been installed at the Caltech Palomar Observatory to pickup information sent by the spacecraft. Communication has always been a great challenge in space exploration and, whilst we cannot reduce transit time for data, we can improve the amount of data sent at any one time. A great step forward in space exploration. 

Source : NASA’s Optical Comms Demo Transmits Data Over 140 Million Miles

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