Astronomy

A new set of images has been released from Europe's "dark universe detective" Euclid, and they show that the space telescope is set to change the game for astronomy.

I love the concept of a ‘puffy’ planet! The exoplanets discovered that fall into this category are typically the same size of Jupiter but 1/10th the mass! They tend to orbit their host star at close in orbits and are hot but one has been found that is different from the normal. This Neptune-mass exoplanet has been thought to be cooler but still have a lower density. The James Webb Space Telescope (JWST) has recently discovered that tidal energy from its elliptical orbit keeps its interior churning and puffs it out. 

WASP-107b is more than three quarters the volume of Jupiter but, like most fluffy planets, is one-tenth the mass making it one of the least dense planets known. Its unusual property however is that whilst most puffy planets are hot, WASP-107b is relatively cool. This goes against initial observations which had also suggested, due to its mass, radius and age it was thought to have a small rock core with a hydrogen and helium rich atmosphere.

Recent observations of this exoplanet by the JWST revealed far less methane in the atmosphere than expected. The orientation of the orbit making it edge on to us means we can study the planet’s atmosphere by examining the light from the star as it passes through the gas. This technique known as transmission spectroscopy can be used to identify the signatures of gasses in the star’s spectrum. Using JWSTs Near-Infrared Camera and Mid-Infrared Instrument and data from Hubble’s Wide Field Camera 3, the abundances of methane, water vapour, carbon dioxide, carbon monoxide, sulphur dioxide and ammonia could be revealed.

Artist impression of the James Webb Space Telescope

Not only did this reveal the lack of methane but also provided evidence that hot gas from lower altitudes was mixing with cooler gas layers from higher up. One of the properties of methane is that it is unstable at high temperatures and, beyond 1200 degrees the bonds between hydrogen and carbon breakdown. This is not the case with other carbon based molecules suggesting the higher temperature.  It suggests that the interior of the planet must be hotter than thought with a more massive core than expected. It’s thanks to JWST’s higher level of sensitivity that the mystery looks like it may finally have been solved.

The team, led by Luis Welbanks from Arizona State University (ASU) explored a number of possibilities. First that it had more mass in its core than first expected. If this was true then the atmosphere is likely to have contracted as the planet cooled. In time and, without a source of heat to give the atmosphere energy and cause it to expand, the planet should be much smaller than observed. Even though the planet orbits the star at a distance of of just over 8 million kilometres it still does not get enough energy to drive the inflation of the atmosphere. 

One theory is that the higher internal temperatures are generated by tidal heating. In just the same way that the gravitational force of Jupiter causes tidal heating on Io, the highly elliptical orbit of WASP-107b could be the answer. As the planet swings by the host star in its non-circular orbit it is squished and squashed providing a source of heat. 

Understanding the source of heat on WASP-107b has helped the team learn more about the properties and processes. Knowing how much energy is there helps to determine the proportions of other elements like carbon, nitrogen, oxygen and sulphur. Calculating this helps to determine the mass of the core  which, according to the recent studies reveal is twice as massive as originally estimated.

Source : Webb Cracks Case of Inflated Exoplanet

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Image: An iceberg roughly the size of the Isle of Wight has broken off the Brunt Ice Shelf in Antarctica on 20 May.

New survey data estimates that 7.1 million children in the US have been diagnosed with ADHD at some point, about 1 million more kids than had been diagnosed as of 2016

New survey data estimates that 7.1 million children in the US have been diagnosed with ADHD at some point, about 1 million more kids than had been diagnosed as of 2016

It’s been 20 years in the making, but a 3200-megapixel camera built especially for astrophysics discoveries has finally arrived at its home. The Legacy of Space and Time (LSST) camera was delivered to the Vera C. Rubin Observatory in Chile in mid-May, 2024.

The camera traveled from its construction lab at the SLAC National Accelerator Laboratory. The technical crew outfitted it with specialized data loggers, monitors, and GPS attached to track the conditions of its trip. Then they put it into a specially built container and the whole assemblage made the trip from San Francisco airport to Santiago on the 14th of May via a chartered flight. Once in Chile, it traveled up to the site for five hours up a 35-kilometer dirt road. It arrived on the 16th, completing a huge step toward opening the Rubin Observatory, according to construction project manager. “Getting the camera to the summit was the last major piece in the puzzle,” he said. “With all Rubin’s components physically on-site, we’re on the home stretch towards transformative science with the LSST.”

This video documents the journey of the LSST Camera from SLAC National Accelerator Laboratory in California to Rubin Observatory on the summit of Cerro Pachón in Chile. The camera arrived on the summit on 16 May 2024. Credit:RubinObs/NSF/AURA/S. Deppe/O. Bonin, T. Lange, M. Lopez, J. Orrell (SLAC National Lab)

The LSST Camera is the final major component of Rubin Observatory’s Simonyi Survey Telescope to arrive at the summit. It’s about the size of a small car. Inside, its focal plane contains 189 CCD sensors arranged on an array of “rafts”. The sensors deliver a combined 3200-megapixel view.

Now that it has arrived, the camera undergoes several months of testing in the observatory’s white room. After that, it goes on the Simonyi Survey Telescope, with its newly-coated 8.4-meter mirror and 3.4-meter secondary mirror.

About the Vera Rubin Observatory

This unique observatory is named after astronomer Vera C. Rubin. Her work focused on the mysterious “dark matter” that seems to permeate the Universe. Along with her team, she studied dozens of galaxies to understand what was influencing their motions. It turned out to be dark matter. The search for dark matter and its existence throughout the Universe is one of the main goals of the observatory that now bears her name.

Understanding the distribution of dark matter is where the LSST Camera will come in handy. For one thing, it will spend a decade taking images of the sky each night, performing a massive survey that will provide a complete image of the visible sky every 3-4 mights. Each area it images will be about the size of 40 full moons and the survey will take advantage of the 8.4-meter telescope moving quickly between imaging positions. In full operation, the Observatory will deliver a 500-petabyte set of images and data products about the sky.

The complete focal plane of the future LSST Camera is more than 2 feet wide and contains 189 individual sensors that will produce 3,200-megapixel images. Crews at SLAC have now taken the first images with it. (Jacqueline Orrell/SLAC National Accelerator Laboratory)

Not only will the Rubin Observatory perform this unprecedented survey in very high resolution, but will also track objects that change in brightness—called “transients.” That includes supernovae, variable stars, mergers of dense objects such as neutron stars or black holes, and other quickly changing events and objects. In addition, it will track asteroids and other objects that wander through the Solar System.

The formation and evolution of the Milky Way Galaxy is another research area for telescope users. Rubin should be able to track stellar streams throughout the Galaxy and chart their paths. That information could give precious insight into just how our Galaxy formed and how stars from cannibalized galaxies move through it.

What’s Next for Vera Rubin Observatory and the LSST Camera

Once the LSST Camera got delivered to the Cerro Pachón site, technicians moved it into an immense white room. That’s a controlled environment that protects the instrument while they work to get it ready for installation on the telescope. They inspected the camera and downloaded data about the “ride” from the U.S. to Chile from all the instruments attached to it. “Our goal was to make sure the camera not only survived, but arrived in perfect condition,” said Kevin Reil, Observatory Scientist at Rubin. “Initial indications—including the data collected by the data loggers, accelerometers, and shock sensors—suggest we were successful.”

View of Rubin Observatory at sunset in December 2023. The 8.4-meter telescope at Rubin Observatory, equipped with the highest-resolution digital camera in the world, will take enormous images of the southern hemisphere sky, covering the entire sky every few nights. Rubin will do this over and over for 10 years, creating a timelapse view of the Universe. Image Credit: RubinObs/NSF/AURA/H. Stockebrand

The observatory is still in the final stages of construction. The telescope is in place, and other instruments and infrastructure are being finalized. It should all be ready for “first light” and the beginning of science operations sometime in 2025. Between now and then, more parts of the telescope and its mirrors should be installed, and there will be tests of various other instruments both on and off the sky as scientists get ready to start using Rubin next year. Once observations begin, astronomers using Rubin could discover around 17 billion stars and ~20 billion galaxies in the distant Universe.

For More Information

LSST Camera Arrives at Rubin Observatory in Chile, Paving the Way for Cosmic Exploration
Vera C. Rubin Observatory

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Roughly 1,000 light-years from Earth, there is a cosmic structure known as IRAS 23077+6707 (IRAS 23077) that resembles a giant butterfly. Ciprian T. Berghea, an astronomer with the U.S. Naval Observatory, originally observed the structure in 2016 using the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). To the surprise of many, the structure has remained unchanged for years, leading some to question what IRAS 2307 could be.

Recently, two international teams of astronomers made follow-up observations using the Submillimeter Array at the Smithsonian Astrophysical Observatory (SAO) in Hawaii to better understand IRAS 2307. In a series of papers describing their findings, the teams revealed that IRAS 23077 is actually a young star surrounded by a massive protoplanetary debris disk, the largest ever observed. This discovery offers new insight into planet formation and the environments where this takes place.

The first paper, led by Berghea, reports the discovery that IRAS 23077 is a young star located in the middle of what appeared to be an enormous planet-forming disk. In the second paper, led by CfA postdoc Kristina Monsch, the researchers confirm the discovery of this protoplanetary disk using data from Pan-STARRS and the Submillimeter Array (SMA). The first paper has been accepted for publication, while the second was published on May 13th in The Astrophysical Journal Letters (respectively).

An illustration of a protoplanetary disk. The solar system formed from such a disk. Astronomers suggest this birthplace was protected by a larger filament of molecular gas and dust early in history. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

Protoplanetary disks are basically planetary nurseries consisting of the gas and dust that have settled around newly formed stars. Over time, these disks become rings as material coalesces into protoplanets in certain orbits, where they will eventually become rocky planets, gas giants, and icy bodies. For astronomers, these disks can be used to constrain the size and mass of young stars since they rotate with a specific signature. Unfortunately, obtaining accurate observations of these disks is sometimes hampered by how they are oriented relative to Earth.

Whereas some disks appear “face-on” in that they are fully visible to Earth observers, some planet-forming disks (like IRAS 23077) are only visible “edge-on,” meaning the disk obscures light coming from the parent star. Nevertheless, the dust and gas signatures of these disks are still bright at millimeter wavelengths – which the SMA observes. When the Pan-STARRS and SWA teams observed IRAS 23077 using the combined power of their observatories, they were quite surprised by what they saw.

Kristina Monsch, an SAO astrophysicist and a postdoctoral fellow at the CfA, led the SMA campaign. As she related their findings in a recent CfA news release:

“After finding out about this possible planet-forming disk from Pan-STARRS data, we were keen to observe it with the SMA, which allowed us to understand its physical nature. What we found was incredible – evidence that this was the largest planet-forming disk ever discovered. It is extremely rich in dust and gas, which we know are the building blocks of planets.”

“The data from the SMA offer us the smoking–gun evidence that this is a disk, and coupled with the estimate of the system’s distance, that it is rotating around a star likely two to four times more massive than our own Sun. From the SMA data we can also weigh the dust and gas in this planetary nursery, which we found has enough material to form many giant planets – and out to distances over 300 times further out than the distance between the Sun and Jupiter!”

The inset for this image shows compelling evidence that IRAS 23077 contains a planet-forming disk. Along with dust grains, the SMA can also observe the cold carbon monoxide gas that comprises the bulk of a planet-forming disk. Credit: SAO/ASIAA/SMA/K. Monsch et al.; Optical: Pan-STARRS

After Berghea observed IRAS 23077, he suggested the nickname “Dracula’s Chivito,” which paid tribute to “Gomez’s Hamburger,” another protoplanetary disk that is only visible edge-on. First, Since Berghea grew up in the Transylvania region in Romania, close to where Vlad the Impaler (the inspiration for Bram Stoker’s tale) lived, he suggested Dracula. Having grown up in Uruquay, Berghea’s co-author Ana suggested “chivito,” a hamburger-like sandwich and the national dish of her ancestral country. Said co-author Joshua Bennett Lovell, an SAO astrophysicist and an SMA Fellow at CfA:

“The discovery of a structure as extended and bright as IRAS 23077 poses some important questions. Just how many more of these objects have we missed? Further study of IRAS 23077 is warranted to investigate the possible routes to form planets in these extreme young environments, and how these might compare to exoplanet populations observed around distant stars more massive than our Sun.”

The discovery of this disk also incentivizes astronomers to search for similar objects in our galaxy. These observations could yield valuable information on planetary systems in the earliest stage of formation, which could lead to new insights into how the Solar System came to be. The SMA is an array of telescopes in Hawaii jointly operated by the Smithsonian Astrophysical Observatory (SAO) at the Harvard & Smithsonian Center for Astrophysics (CfA) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in Taiwan.

Further Reading: CfA

The post This is the Largest Planet-Forming Disk Ever Seen appeared first on Universe Today.

Ultra-hot Jupiters (UHJs) are some of the most fascinating astronomical objects in the cosmos, classified as having orbital periods of less than approximately 3 days with dayside temperatures exceeding 1,930 degrees Celsius (3,500 degrees Fahrenheit), as most are tidally locked with their parent stars. But will these extremely close orbits result in orbital decay for UHJs eventually doom them to being swallowed by their star, or can some orbit for the long term without worry? This is what a recent study accepted to the Planetary Science Journal hopes to address as a team of international researchers investigated potential orbital decays for several UHJs, which holds the potential to not only help astronomers better understand UHJs but also the formation and evolution of exoplanets, overall.

Here, we discuss this research with study lead author, Dr. Elisabeth Adams, who is a Senior Scientist at the Planetary Science Institute, regarding the motivation behind the study, significant results, follow-up studies, and the importance of studying orbital decay for UHJs and UHJs, overall. So, what was the motivation behind this study regarding the orbital decay of UHJs? 

“Ever since the first exoplanet, 51 Peg b aka Dimidium, was announced in a 4-day orbit, scientists have been deeply concerned about the long-term stability of these giant planets,” Dr. Adams tells Universe Today. “We’ve known for a while that objects the size of Jupiter can’t exist with orbits shorter than about 19 hours (that’s the Roche limit), but even giant planets with orbits of a few days are unstable over the long term because the tidal forces will inexorably cause their orbits to decay. The big unknown is what ‘long-term’ means: will the planet decay while the star is still on the main sequence, or will the process take so long that the star dies first?”

For the study, the researchers used a combination of ground- and space-based telescopes to conduct stellar photometry and exoplanet light curve analyses of 43 UHJs with orbital periods ranging from 0.67 days (TOI-2109 b) to 3.03 days (TrES-1 b) with the goal of ascertaining their orbital period rate of change (i.e., increasing orbital period or decreasing orbital period (orbital decay)) measured in milliseconds per year (ms/yr). This study consisted of both previously measured and new transit light curve data with the team performing some calculations to determine the orbital period rate of change for each of the 43 UHJs. Additionally, more than half of the 43 UHJs for this study have observational data of more than a decade with one exceeding 20 years of data (WASP-18 b at 32 years). So, what were the most significant results from this study?

Dr. Adams tells Universe Today, “The interesting thing is not only that this study didn’t find any new cases of orbital decay, but also that we are starting to see several orders of magnitude difference in how long orbital decay takes. The two best cases for decaying planets (WASP-12 b and Kepler-1658 b) are decaying at rates that are >10-1000 times faster than the planets that we don’t find decay around (e.g., WASP-18 b, WASP-19b, and KELT-1b); if those latter planets were decaying as fast as WASP-12 b, we definitely would have detected it by now.”

As noted, this comprehensive study helped identify new information regarding the orbital decay of UHJs, specifically pertaining to the lack of orbital decay for most of them, meaning some orbits could potentially be stable for the long-term despite orbiting extremely close to their respective parent stars. Additionally, it helped challenge previous measurements pertaining to orbital decay of certain UHJs, which could help astronomers better understand the formation and evolution of UHJs throughout the universe. Therefore, given the comprehensiveness of the study, what follow-up studies are currently in the works or being planned?

Dr. Adams tells Universe Today, “We’re just going to have to keep looking! This paper is the first one from our survey, and only covers about half the known UHJs, more of which keep being found; among our targets, half of them haven’t been observed long enough, or with enough transits, to say if even very rapid orbital decay is happening. For the others, we may just need another few more years, or maybe a few decades, to observe it. Theorists are also hard at work to explain how the age and structure of the star contribute to different rates of decay, though the high uncertainty between theoretical models is why I like being able to empirically measure the decay rate.”

Studying orbital decay is essential in better understanding both if and when two astronomical objects will collide with each other, including a planet and its satellite (most often a moon), a star and another planet or comet orbiting it (resulting in the latter’s incineration), a star and another star (resulting in gravitational waves or gamma-ray bursts), and any astronomical objects orbiting each other (binary system). For Earth, measuring orbital decay has been vital in learning when artificial satellites could burn up in our planet’s atmosphere. But, regarding exoplanets, what is the importance of studying orbital decay for UHJs, and are they limited to only UHJs?

“Tidal decay is most important for large planets,” Dr. Adams tells Universe Today. “Crazily enough, Earth-sized planets have been found in orbits as short as 4 hours and yet are predicted to be tidally stable for many billions of years. (I have previously published work on these smaller ultra-short period planets.) The bigger the planet and the closer it is to the star, the stronger the tidal effects and the faster the orbit will decay.”

UHJs are unofficially designated as a sub-class of “hot” Jupiters. Like this study, past UHJs have also been examined using a combination of ground- and space-based telescopes. As noted by Dr. Adams, this study examined approximately half of the known UHJs, meaning there are approximately 100 known UHJs populating the cosmos. As also noted, most UHJs are tidally locked with their parent star, meaning one side continuously faces the star throughout its orbit with the searing dayside temperatures causing molecules to break apart and recombine on the night side. These characteristics make UHJs some of the most intriguing and mysterious astronomical objects to be studied. But what is the importance of studying UHJs, overall?

“Ultra-hot Jupiters allow us to measure a fundamental property of stars (the tidal quality factor, which sets the decay rate),” Dr. Adams tells Universe Today. “Modeling their pasts and futures allows us to refine our theories of planet formation and migration. Some of them might also be losing their atmospheres, which we can look for.  They are also some of the easiest planets to observe because they are big and hot and close to their star and make excellent targets for both high-precision observations (e.g., atmospheric studies with JWST) and outreach (they are excellent targets for interested amateurs with decent telescopes).”

This study comes as NASA and other space agencies around the world continue to discover exoplanets at an incredible rate, with NASA listing the number of confirmed exoplanets at 5,630 as of this writing. Of that number, 1,805 are classified as gas giants (Saturn- or Jupiter-sized), with countless numbers of these worlds orbiting their parent stars in just a few days or less. As our understanding of exoplanets continues to expand, so will our understanding of UHJs, including their formation and evolution, along with the formation and evolution of their parent stars.

“My motto for studying exoplanets is to expect the unexpected,” Dr. Adams tells Universe Today. “Even after three decades of observations we keep finding planets in unexpected places doing strange things, and then we learn a lot about the universe by figuring out what they are doing and why. Definitely keeps you on your toes!”

What new discoveries will researchers make about ultra-hot Jupiters in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Maybe Ultra-Hot Jupiters Aren’t So Doomed After All appeared first on Universe Today.

NASA will keep safety front of mind while harnessing the ever-growing power of artificial intelligence, agency officials stressed.

If alien technological civilizations exist, they almost certainly use solar energy. Along with wind, it’s the cleanest, most accessible form of energy, at least here on Earth. Driven by technological advances and mass production, solar energy on Earth is expanding rapidly.

It seems likely that ETIs (Extraterrestrial Intelligence) using widespread solar energy on their planet could make their presence known to us.

If other ETIs exist, they could easily be ahead of us technologically. Silicon solar panels could be widely used on their planetary surfaces. Could their mass implementation constitute a detectable technosignature?

The authors of a new paper examine that question. The paper is “Detectability of Solar Panels as a Technosignature,” and it’ll be published in The Astrophysical Journal. The lead author is Ravi Kopparapu from NASA’s Goddard Space Flight Center.

In their paper, the authors assess the detectability of silicon-based solar panels on an Earth-like habitable zone planet. “Silicon-based photovoltaic cells have high reflectance in the UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept like the Habitable Worlds Observatory (HWO),” the authors write. The HWO would search for and image Earth-like worlds in habitable zones. There’s no timeline for the mission, but the 2020 Decadal Survey recommended the telescope be built. This research looks ahead to the mission or one like it sometime in the future.

Naturally, the authors make a number of assumptions about a hypothetical ETI using solar power. They assume that an ETI is using large-scale photovoltaics (PVs) based on silicon and that their planet orbits a Sun-like star. Silicon PVs are cost-effective to produce, and they are well-suited to harness the energy from a Sun-like star.

Kopparapu and his co-authors aren’t the first to suggest that silicon PVs could constitute a technosignature. In a 2017 paper, Avi Loeb and Manasvi Lingam from the Harvard-Smithsonian Center for Astrophysics wrote that silicon-based PVs create an artificial edge in their spectra. This edge is similar to the ‘red edge‘ detectable in Earth’s vegetation when viewed from space but shifted to shorter wavelengths. “Future observations of reflected light from exoplanets would be able to detect both natural and artificial edges photometrically if a significant fraction of the planet’s surface is covered by vegetation or photovoltaic arrays, respectively,” Lingam and Loeb wrote.

“The “edge” refers to the noticeable increase in the reflectance of the material under consideration when a reflected light spectrum is taken of the planet,” the authors of the new research explain. Satellites monitor the red edge on Earth to observe agricultural crops, and the same could apply to sensing PVs on other worlds.

This figure shows the reflection spectrum of a deciduous leaf (data from Clark et al. 1993). The large sharp rise (between 700 and 800 nm) is known as the red edge and is due to the contrast between the strong absorption of chlorophyll and the otherwise reflective leaf. Image Credit: Seager et al. 2005.

While Lingam and Loeb suggested the possibility, Kopparapu and his co-authors dug deeper. They point out that we could generate enough energy for our needs (as of 2022) if only 2.4% of the Earth’s surface was covered in silicon-based PVs. The 2.4% number is only accurate if the chosen location is optimized. For Earth, that means the Sahara Desert, and something similar may be true on an alien world.

The authors explain, “This region is both close to the equator, where a comparatively greater amount of solar energy would be available throughout the year, and has minimal cloud coverage.”

The authors also work with a 23% land coverage number. This number reflects previous research showing that for a projected maximum human population of 10 billion people, 23% land coverage would provide a high standard of living for everyone. They also use it as an upper limit because anything beyond that seems highly unlikely and would have negative consequences. On Earth, the entire continent of Africa is about 23% of the surface.

The authors’ calculations show that an 8-meter telescope similar to the HWO would not detect an Earth-like exoplanet with 2.4% of its surface covered with PVs.

If an ETI covered 23% of its surface with energy-harvesting PVs, would that be detectable? It would be difficult to untangle the planet’s light from the star’s light and would require hundreds of hours of observation time to reach an acceptable Signal-to-Noise (S/N) ratio.

“Because we have chosen the 0.34 ?m–0.52?m range to calculate the impact of silicon panels on the reflectance spectra, the difference between a planet with and without silicon is not markedly different, even with 23% land cover,” the authors explain.

Technological progress adds another wrinkle to these numbers. As PV technology advances, an ETI would cover less of its planet’s surface area to generate the same amount of energy, making detection even more difficult.

This figure from the research shows the planet-star contrast ratio as a function of wavelength for
2.4 % land coverage with PVs (blue solid), 23 % PVs (red solid) and 0% (green dashed) land coverage of solar panels. “This suggests that the artificial silicon edge suggested by Lingam & Loeb (2017) may not be detectable,” the authors write. Image Credit: Kopparapu et al. 2024.

Solar energy is expanding rapidly on Earth. Each year, more individual homes, businesses, and institutions implement solar arrays. Those might not constitute technosignatures, but individual installations aren’t the only thing growing.

China built a vast solar power plant called the Gonghe Photovoltaic Project in its sparsely populated Qinghai Province. It generates 3182 MW. India has the Bhadla Solar Park (2,245 MW) in the Thar Desert. Saudi Arabia has built several new solar plants and intends to build more. Other innovative solar projects are announced regularly.

But will we realistically ever cover 2.4% of our planet in solar arrays? Will we need to? There are many questions.

Generating solar power in the heat of the Sahara Desert is challenging. The extreme heat reduces efficiency. Building the infrastructure required to deliver the energy to population centres is also another challenge. Then consider that silicon-based PVs may not be the end point in solar panel development. Perovskite-based PVs hold a lot of promise to outperform silicon. They’re more efficient than silicon, and researchers frequently break energy records with them (in laboratories.) Would perovskite PVs create the same “edge” in a planet’s spectra?

The authors didn’t consider specific technological advances like perovskite because it’s beyond the scope of their paper.

The bottom line is that silicon-based solar arrays on a planetary surface are unlikely to create an easily detectable technosignature. “Assuming an 8-meter HWO-like telescope, focusing on the reflection edge in the UV-VIS, and considering varying land coverage of solar panels on an Earth-like exoplanet that match the present and projected energy needs, we estimate that several hundreds of hours of observation time is needed to reach a SNR of ~5 for a high land coverage of ~23%,” the authors write.

The Bhadla Solar Park is a large PV installation that aims to generate over 2,000 MW of solar energy. Image Credit: (Left) Google Earth. (Right) Contains modified Copernicus Sentinel data 2020, Attribution, https://commons.wikimedia.org/w/index.php?curid=90537462

The authors also wonder what this means for the Kardashev Scale and things like Dyson Spheres. In that paradigm, ETIs require more and more energy and eventually build a mega engineering project that harvests all of the energy available from their star. A Dyson Sphere would create a powerful technosignature, and astronomers are already looking for them.

But if the numbers in this research are correct, we may never see one because they’re not needed.

“We find that, even with significant population growth, the energy needs of human civilization would be several orders of magnitude below the energy threshold for a Kardashev Type I civilization or a Dyson sphere/swarm which harnesses the energy of a star,” they conclude. “This line of inquiry reexamines the utility of such concepts and potentially addresses one crucial aspect of the Fermi paradox: We have not discovered any large-scale engineering yet, conceivably because advanced technologies may not need them.”

The post Could Alien Solar Panels Be Technosignatures? appeared first on Universe Today.

A familiar sight from Georgia, USA, the

There are millions of asteroids floating around the solar system. With so many of them, it should be no surprise that some are weirdly configured. A recent example of one of these weird configurations was discovered when Lucy, NASA’s mission to the Trojan asteroids, passed by a main-belt asteroid called Dinkinesh. It found that Dinkinesh had a “moon” – and that moon was a “contact binary”. Now known as Selam, it is made up of two objects that physically touch one another through gravity but aren’t fully merged into one another. Just how and when such an unexpected system might have formed is the subject of a new paper by Colby Merrill, a graduate researcher at Cornell, and their co-authors at the University of Colorado and the University of Bern.

The paper, in particular, looks at when the system might have formed and does so through modeling. A theory in asteroid formation called the binary Yarkovsky-O’Keefe-Radzievskii-Paddack effect, which, since no one wants to say the full name, is shortened to the acronym BYORP. This model explains how binary asteroid systems happen in the first place. 

Essentially, the asteroid speeds up its rotation due to radiation pressure. Eventually, due to those rotational forces, it gets to a point where its gravity is no longer capable of holding all of its material on its surface, and some of that material is ejected out into space, eventually coalescing into a “moon” for the slightly larger asteroid.

Video from NASA Goddard showing the image from Lucy that found Selam.
Credit – NASA Goddard YouTube Channel

Dinkinesh isn’t a “large” asteroid by any measure – at its widest point, it only measures about 790 meters in diameter. It’s also named after the Amharic word for Lucy; the fossil remains of a potential human ancestor found in Ethiopia and the namesake of NASA’s mission. Its satellite, Salem, is the Amharic word for “peace,” but another fossil set found in 2000 which, though that of a child, predated Lucy’s by 100,000 years. But it is even smaller than Dinkinesh – only about 220 m at its widest point.

But Selam actually has two widest points because it is shaped in what is technically called a bilobate but is more commonly thought of as a “dumbbell” shape. This might be partially due to another force that influences the formation of asteroids—tides. 

Traditionally, people think of tides as caused by our Moon moving around the Earth. However, tides can also happen on the insides of asteroids when there is a gravitational force on a small body by an even smaller one that happens to be nearby. For example, Selam induces tides on Dinkinesh, and understanding how the two developed together requires understanding how those tidal forces played out.

Close up of Dinkinesh & Selam from Lucy.
Credit – NASA/Goddard/SwRI/John Hopkins APL/NOIRLab/Brian May/Claudia Manzoni

Modeling both tidal forces and the BYROP acceleration process is complex mathematically. This is especially true because the inputs to the equations used to model them contain plenty of uncertainties. Luckily, there is a mathematical technique to help with that.

The Monte Carlo method uses statistics to find a “correct” answer by varying the inputs to equations and randomly sampling the results. The authors used this technique to determine how long the Dinkinesh / Selam system had been in orbit around each other, using inputs like each object’s sizes and orbital speeds. They came up with an answer of between 1 and 10 million years – not very long in the grand scheme of the solar system’s evolution.

Given that binaries are thought to make up at least 15% of near-Earth asteroids, and contact binaries make up between 14% and 30% of small bodies that are still larger than 200 m, studying these kinds of unexpected systems could prove fruitful in understanding how asteroids more generally are formed. As the paper mentions, more work is needed, especially an analysis of the craters present on Selam, which could provide an alternative view of its age. Given that we only just discovered this binary system by chance in November 2023, that data, and much else from the Lucy mission, will doubtless be forthcoming soon.

Fraser discusses the discovery of Selam.

Learn more:
Merrill et al. – Age of (152830) Dinkinesh I Selam constrained by secular tidal-BYORP theory
UT – Contact Binary Asteroids are Common, but We’ve Never Seen One Form. So Let’s Make One
UT – Awesome Radar Images Reveal Asteroid 2014 HQ124’s Split Personality
UT – What? Wow! That New Asteroid Image from Lucy Just Got Even More Interesting

Lead Image:
Dinkinesh and Selam in situ via a Lucy snapshot.
Credit – NASA/Goddard/SwRI/John Hopkins APL

The post Finding The Age Of A Contact Binary “Moon” appeared first on Universe Today.

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