Astronomy

Image: YPSat checked in for Ariane 6 flight

Lunar I-Hab, the next European habitat in lunar orbit as part of the Gateway, has recently undergone critical tests to explore and improve human living conditions inside the space module.

How can machine learning help astronomers find Earth-like exoplanets? This is what a recently accepted study to Astronomy & Astrophysics hopes to address as a team of international researchers investigated how a novel neural network-based algorithm could be used to detect Earth-like exoplanets using data from the radial velocity (RV) detection method. This study holds the potential to help astronomers develop more efficient methods in detecting Earth-like exoplanets, which are traditionally difficult to identify within RV data due to intense stellar activity from the host star.

The study notes, “Machine learning is one of the most efficient and successful tools to handle large amounts of data in the scientific field. Many algorithms based on machine learning have been proposed to mitigate stellar activity to better detect low-mass and/or long period planets. These algorithms can be classified into two categories: supervised learning and unsupervised learning. The advantage of supervised learning is that the proposed model contains a large set of variables and has the ability to produce relatively accurate predictions based on the training data.”

For the study, the researchers applied their algorithm to three stars to ascertain its ability to identify exoplanets within the stellar activity data: our Sun, Alpha Centauri B (HD 128621), and Tau ceti (HD 10700), with Alpha Centauri B being located approximately 4.3 light-years from Earth and Tau ceti being located approximately 12 light-years from Earth. After inserting simulated planetary signals within the algorithm, the researchers found their algorithm successfully identified simulated exoplanets with potential orbital periods ranging between 10 to 550 days for our Sun, 10 to 300 days for Alpha Centauri B, and 10 to 350 days for Tau ceti. It’s important to note that Alpha Centauri B currently has had several potential exoplanet detections but non confirmed while Tau ceti currently has eight exoplanets listed as “unconfirmed” within its system.

Additionally, the algorithm identified these results correspond to Alpha Centauri B and Tau ceti potentially having exoplanets approximately 4 times the size of Earth and within the habitable zones of those stars, as well. After inserting more stellar activity data into the algorithm, the researchers discovered the algorithm successfully identified a simulated exoplanet approximately 2.2 times the size of the Earth while orbiting the same distance as the Earth from our Sun.

The study noted in its conclusions, “In this paper, we developed a neural network framework to efficiently mitigate stellar activity at the spectral level, to enhance the detection of low-mass planets on periods from a few days up to a few hundred days, corresponding to the habitable zone of solar-type stars.”

While the study focused on finding Earth-like exoplanets within RV data, the researchers note that additional data, including transit time, phase, and space-based photometry, could be used to identify Earth-like exoplanets. They emphasize the European Space Agency’s PLATO space telescope mission could accomplish this, which is currently being developed and slated for launch sometime in 2026. Upon launch, it will be stationed at the Sun-Earth L2 Lagrange point located on the opposite side of the Earth from the Sun where it scan up to one million stars searching for exoplanets using the transit method with an emphasis on terrestrial (rocky) exoplanets.

PLATO mission discussed around the 9:00 mark

This study comes as the number of confirmed exoplanets by NASA has reached 5,632 as of this writing, which is comprised of 201 terrestrial exoplanets, and also provides the upcoming PLATO mission ample opportunity to discover many more terrestrial exoplanets within our Milky Way Galaxy.

How will machine learning help astronomers detect Earth-like exoplanets 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 A New Deep Learning Algorithm Can Find Earth 2.0 appeared first on Universe Today.

Universe Today has had the privilege of spending the last several months venturing into a multitude of scientific disciplines, including impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics, cosmochemistry, meteorites, radio astronomy, extremophiles, organic chemistry, and black holes, and their importance in helping teach scientists and the public about our place in the cosmos.

Here, we discuss the intriguing field of cryovolcanism with Dr. Rosaly Lopes, who is the Directorate Scientist for the Planetary Science Directorate and a Senior Research Scientist at NASA’s Jet Propulsion Laboratory, regarding the importance of studying cryovolcanism, examples throughout the solar system, what cryovolcanism can teach us about finding life beyond Earth, exciting aspects of studying cryovolcanism, and advice for upcoming students who wish to study cryovolcanism. So, what is the importance of studying cryovolcanism?

Dr. Lopes references Geissler (2015) and tells Universe Today, “My colleague Paul Geissler defined it well: ‘The eruption of liquid or vapor phases (with or without entrained solids) of water or other volatiles that would be frozen solid at the normal temperature of the icy satellite’s surface’.

While we associate volcanism on Earth as being when hot magma erupts from the Earth’s interior into a fiery blaze and melting everything in its path, cryovolcanism is the study of ice volcanism, as “cryo” is defined as “ice cold” or “frost”. The term was first used in an abstract at the 1987 Geological Society of America (GSA) Abstract with Programs by Steven K. Croft and has since been used to describe ice volcanoes throughout the solar system. Additional terms used in the context of cryovolcanism include cryomagma and cryolava—comparable to magma and lava from traditional volcanoes—and cryovolcanic edifice—comparable to traditional shield volcanoes seen both on Earth and other planetary bodies (i.e., Mars and Venus). Therefore, what are some examples of cryovolcanism in our solar system?

Dr. Lopes tells Universe Today, “We see active cryovolcanism on Enceladus, and signs of past cryovolcanism on Titan, Europa, Ganymede, and even Io (SO2 rather than water).” Dr. Lopes elaborates more on active and past volcanism in a 2010 book chapter, as well.

The reason we see active cryovolcanism on Saturn’s moon, Enceladus, is due to the large liquid water ocean it possesses beneath its icy crust, with NASA’s Cassini spacecraft having not only imaged active plumes erupting from Enceladus’ south pole “Tiger Stripes”, but Cassini also flew through the plumes in March 2008, using its Ion and Neutral Mass Spectrometer (INMS) to identify water vapor, carbon dioxide, carbon monoxide, and organic materials, whose levels were higher than the Cassini team had hypothesized prior to the flyby.

Saturn’s largest moon, Titan, is home to bodies of liquid methane and ethane across its surface due to the frigid surface temperatures of -182.55 degrees Celsius (-296.59 degrees Fahrenheit), whereas methane and ethane exist strictly as gases on Earth. Regarding evidence for past cryovolcanism on Titan, the Cassini spacecraft discovered Doom Mons in 2005 and Erebor Mons in 2007, with both currently being generally accepted as cryovolcanoes. Additionally, Cassini used its radar instruments in 2018 to identify topography on Titan that was identified as the “very best evidence” for a cryovolcano on Titan.

Like Enceladus, Jupiter’s two Galilean Moons, Europa and Ganymede, have exhibited significant evidence that they both contain interior liquid oceans beneath their icy crusts, and NASA’s Europa Clipper mission is slated to launch this October to explore this icy world in detail once it arrives sometime in 2030. Additionally, the European Space Agency’s Jupiter Icy Moons Explorer (JUICE) mission launched in April 2023 with the goal of studying Ganymede in detail and is currently scheduled to enter Ganymede’s orbit sometime in late 2034.

Regarding evidence of past cryovolcanism on Europa, scientists postulated in 2020 that plumes observed to emanate from Europa could originate from directly within the icy crust. For Ganymede, specific surface features known as paterae have indicated “potential cryovolcanic regions”, but scientists remain skeptical and have listed these features as something the JUICE mission should investigate further.

Additional worlds in our solar system that also exhibit past or current evidence of cryovolcanism include the dwarf planet, Ceres; Neptune’s moon, Triton; the dwarf planet, Pluto and its moon, Charon; and other dwarf planets, as well. Therefore, with this plethora of worlds that exhibit current or past evidence of cryovolcanism within our solar system, what can cryovolcanism teach us about finding life beyond Earth?

Dr. Lopes tells Universe Today, “For life as we know it to exist, we need water and energy – cryovolcanism provides the heat (energy) and it is a way to bring material that may have biosignatures to the surface of bodies. If the material just stays in the ocean under an ice crust, it could be many decades before we are able to sample it.”

Regarding the most exciting aspects about cryovolcanism that she has studied during her career, Dr. Lopes tells Universe Today, “Finding Doom Mons and Erebor Mons on Titan was very exciting, as they are the most convincing evidence we have that cryovolcanism happened on Titan.”

Like the other scientific disciplines that Universe Today has explored, the field of cryovolcanism involves the collaboration of scientists from a multitude of backgrounds, including volcanology, planetary geology, physics, and computer science. Through this, scientists can create computer models of cryovolcanism based on existing data, along with using imagery from orbiters to confirm or update their models to ascertain the processes behind the cryovolcanism they have observed. Therefore, what advice can Dr. Lopes offer upcoming students who wish to study cryovolcanism?

Dr. Lopes tells Universe Today, “The physics of the process is still not well understood. Lab experiments are valuable. They should read the literature and figure out how to advance their understanding.”

How will cryovolcanism teach us about our place in the universe 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 Cryovolcanism: Why study it? What can it teach us about finding life beyond Earth? appeared first on Universe Today.

Jupiter’s moon Io is a volcanic powerhouse. It’s the most geologically active world in the Solar System, sporting more than 400 spouting volcanoes and vents on its surface. Has it always been this way? A team of planetary scientists says yes, and they have the chemical receipts to prove it.

In a recent paper, the team headed by CalTech scientist Katherine de Kleer cites data from millimeter observations of elemental isotopes found in Io’s eruptions. They found that chemicals like chlorine and sulfur exist in higher quantities at Io than in comparable places in the Solar System. Analysis shows that Io hasn’t just started erupting lately—it’s been going on for most of its history. And, it’s so volcanic that it practically resurfaces itself every million years or so.

The discovery of volcanism on Io was one of the major results of the Voyager mission. As the two spacecraft swept past Jupiter in 1979, their images revealed Io’s volcanic features and plumes. Since that time, the Galileo, Cassini-Huygens, New Horizons, and Juno missions also sent images. The Jovian system and its moons are also frequent targets for ground- and space-based observatories, including Hubble Space Telescope and JWST.

Facts about Io

Io is the fourth-largest Jovian moon and is one of the four Galilean satellites. It orbits closest to Jupiter and gets pulled by a gravitational tug-of-war between Jupiter and the other Galilean moons. The result is a process called “tidal heating” deep inside Io, produced by friction. That generates heat, which melts Io’s interior, and opens up vents so that the heat and melted material can escape to the surface.

An artist’s concept of the interior of Io. By Kelvinsong – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31526383

This little moon is mostly silicate rock atop an iron or iron sulfide core. The surface is scarred with volcanoes and deformed by compressional forces beneath the crust. The most obvious features are the volcanic mountains, plumes, and lava flows. Currently, Io’s volcanoes resurface the landscape at a rate of about 0.1 to 1.0 cm per year. They also paint its surface in an amazing array of colors. During the Voyager 2 flyby, people often compared its appearance to a pizza. The colors come mainly from sulfur and sulfurous compounds deposited across the landscape.

Normally, geologists would look at its surface and count craters to get an idea of its age. But, since volcanic flows erase craters, there’s no easy visual way to determine how long volcanic features have been around. However, it turns out that abundances of certain isotopes of sulfur and other elements could provide a good record the history of volcanism on Io.

Analyzing Io’s Chemistry

Io has probably lost mass to space throughout its history. de Kleer and her colleagues point out that its supply of volatile elements should be highly enriched in heavy stable isotopes. That’s because atmospheric escape processes generally favor the loss of lighter isotopes. They suggest that stable isotope measurements of volatile elements, such as sulfur and chlorine, could give accurate details about the history of volcanism at Io. So, it makes sense, then, to do a thorough chemical analysis of Io’s volcanic emissions now and extrapolate back.

Understanding Io’s current chemistry, requires, among other things, a good idea of its mass-loss history. Io’s mass loss occurs because of collisions between atmospheric molecules and energetic particles trapped in Jupiter’s magnetosphere. If this continued over Io’s history, then its chemistry should provide evidence of the volcanic past. In their paper, the team discusses the assumptions they made, including estimates of Io’s initial inventory of sulfur, as well as possible early mass-loss rates that could affect its current abundances of sulfur and chlorine—two elements that help determine past and present volcanism.

To get that history, team used the Atacama Large Millimeter Array to observe gases in Io’s atmosphere. The goal was to measure SO2, SO, NaCl, and KCl in various forms and determine the ratios of 34S to 32S and 37Cl to 35Cl. After analyzing the data, the team found that Io has lost at least 94 to 99 percent of its available sulfur over time. In addition, the measurements show enriched levels of chlorine. This probably indicates that Io has been volcanically active throughout time. It’s also possible that this tiny moon has experienced higher rates of outgassing and mass loss early in its history. More measurements should help scientists constrain Io’s volcanic activity even more tightly.

For More Information

Isotopic Evidence of Long-lived Volcanism on Io
Violent Volcanoes Have Wracked Jupiter’s Moon Io for Billions of Years

The post Io Has Been Volcanically Active for its Entire History appeared first on Universe Today.

There are some things that never cease to amaze me and the discovery of distant objects is one of them. The James Webb Space Telescope has just found the most distant galaxy ever observed! It has the catchy title JADES-GS-z14-0 and it has a redshift of 14.32. This means its light left when the Universe was only 290 million years old! That means the light left the source LOOOONG before even our Milky Way was here! How amazing is that!

The James Webb Space Telescope (JWST) with its 6.5m mirror was launched on 25 December 2021 and has quickly proven itself to be the most powerful space telescope ever built. It was designed to explore the Universe in visible and infrared radiation so that it could probe straight through dust to reveal hidden details behind. It is positioned at the second Lagrange point where the gravity of the Earth is balanced by the gravity of the Sun and it maintains a stable 1.5 million km from Earth. 

Artist impression of the James Webb Space Telescope

Over the last couple of years, astronomers have been using JWST to study the Cosmic Dawn! This period of time existed just a few hundred million years after the big bang but studying galaxies so far back in time required the sensitivity of the JWST. They provide valuable information about the gas and stars within and help to understand their formation. 

An international team were using JWST data that had been collected as part of the Advanced Deep Extragalactic Survey (JADES) using the Near-Infrared Spectrograph known as NIRSpec. They were able to acquire a spectrum of the galaxy revealing a redshift of 14.32. The redshift phenomenon occurs when the light from distant objects in space shift toward the red end of the spectrum. It was originally thought this was due to the movement but instead it is caused by the expansion of space. The greater the redshift, the faster the object is moving away and therefore the further away it is. 

The redshift of JADES-GS-z14-0 makes it the most distant galaxy known and it corresponds to the light having been emitted at a time when the Universe was just under 300 million years old. The team estimate the galaxy to be just over 1,600 light years across, that’s in comparison to the Milky Way which is thought to be 100,000 light years across. It is fairly typical of distant, early galaxies to be bright due to gas falling into a supermassive black hole but in the case of JADES-GS-z14-0 the light seems to be created by hot young stars. 

The image that has been released shows a field of thousands of distant galaxies of all manner of shapes, colours and sizes. One solitary bright star is visible in the foreground with the trademark diffraction spikes caused by the JWST optics. A box just to the lower right of centre highlights the location with the zoomed in image of the galaxy superimposed. The galaxy looks very different from those we tend to see in today’s Universe as it appears far less structured. 

Source : Webb finds most distant known galaxy

The post Webb Finds the Farthest Galaxy Ever Seen (So Far) appeared first on Universe Today.

Star formation can be messy.

Boeing's Starliner capsule had a helium leak in one of its thrusters, but it is still scheduled to launch on 1 June for its first crewed flight to the International Space Station

Boeing's Starliner capsule had a helium leak in one of its thrusters, but it is still scheduled to launch on 1 June for its first crewed flight to the International Space Station

A new simulation has shown elusive intermediate-mass black holes may form in dense globular clusters of millions of tightly packed stars, thanks to a chaotic collision chain.

Most of the exoplanets we’ve found are around stars, where they belong. But a few have been found free-floating in interstellar space. The evidence is growing that there are a lot of them out there, maybe even more than planets with stars. How do they form and how can we learn more about them?

OSIRIS-APEX emerged unscathed from its first of six close brushes with the sun, thanks to some clever engineering.

One of the first bioelectronic devices to combine living bacteria with sensors has successfully improved healthy skin regeneration in mice with psoriasis

One of the first bioelectronic devices to combine living bacteria with sensors has successfully improved healthy skin regeneration in mice with psoriasis

James Webb Space Telescope has spotted the two earliest and most distant galaxies ever seen. One, JADES-GS-z14-0, is a massive and bright galaxy that existed just 300 million years after the Big Bang.

On July 14th, 2015, the New Horizons spacecraft conducted the first-ever flyby of Pluto, which once was (and to many, still is) the ninth planet of the Solar System. While the encounter was brief, the stunning images and volumes of data it obtained revealed a stunningly vibrant and dynamic world. In addition to Pluto’s heart, floating ice hills, nitrogen icebergs, and nitrogen winds, the New Horizons data also hinted at the existence of an ocean beneath Pluto’s icy crust. This effectively made Pluto (and its largest moon, Charon) members of the “Ocean Worlds” club.

Almost a decade after that historic encounter, scientists are still making discoveries from New Horizons data. In a new paper, planetary scientists Alex Nguyen and Dr. Patrick McGovern used mathematical models and images to learn more about the possible ocean between Pluto’s icy surface and its silicate and metallic core. According to their analysis, they determined that Pluto’s ocean is located beneath a surface shell measuring 40 to 80 km (25 to 50 mi), an insulating layer thick enough to ensure that an interior ocean remains liquid.

Nguyen is a graduate student in Earth, environmental, and planetary sciences in Arts & Sciences at Washington University in St. Louis (WUSTL), while Dr. McGovern is a Senior Staff Scientist with the Lunar and Planetary Institute (LPI) in Houston. Their paper, “The role of Pluto’s ocean’s salinity in supporting nitrogen ice loads within the Sputnik Planitia basin,” recently appeared in the journal Icarus. The study is part of Nguyen’s Ph.D. research at Washington University, where he is an Olin Chancellor’s Fellow and a National Science Foundation Graduate Research Fellow.

This cutaway image of Pluto shows a section through the area of Sputnik Planitia, with dark blue representing a subsurface ocean and light blue for the frozen crust. Artwork by Pam Engebretson, courtesy of UC Santa Cruz.

For decades, planetary scientists assumed Pluto was far too cold to support an interior ocean. Pluto orbits well beyond the Solar System’s “Frost Line,” the boundary beyond which volatile elements (water, carbon dioxide, ammonia, etc.) become solid. With an average surface temperature of -229 °C (-380°F), even nitrogen and methane become as solid as rock. As Nguyen indicated in a recent interview with The Source (WUSTL’s news site), “Pluto is a small body. It should have lost almost all of its heat shortly after it was formed, so basic calculations would suggest that it’s frozen solid to its core.”

But thanks to New Horizons, scientists were presented with multiple lines of evidence that suggest Pluto likely has an interior ocean. This includes cryovolcanoes, such as those observed on Ceres, Europa, Ganymede, Enceladus, Titan, Triton, and other “Ocean Worlds.” While the existence of this ocean is still subject to debate, the theory is gaining acceptance to the point that it is considered a very real possibility. For their study, Nguyen and McGovern created mathematical models to explain the cracks and bulges in the ice covering Pluto’s Sputnik Planitia Basin.

Their results indicate that an ocean could exist beneath an icy shell 40 to 80 km (25 to 50 mi) thick, which would be sufficient to ensure that Pluto could maintain a liquid water ocean in its interior despite surface conditions. They also calculated the likely density or salinity of the ocean based on the surface features and determined that Pluto’s ocean could be up to 8% denser than Earth’s oceans. This salinity level would make Pluto’s ocean comparable to the Great Salt Lake, the Dead Sea, and other high-salinity bodies of water on Earth.

According to Nguyen, any variations in this density (greater or lower) would be evident from the cracks and fractures in the Sputnik Platina Basin. “We estimated a sort of Goldilocks zone where the density and shell thickness is just right,” he said. If the ocean were less dense, the ice shell would collapse, leading to many more fractures in the surface. If it were denser, the ice sheet would be more buoyed, which would be evident from there being fewer fractures. Unfortunately, it could be many decades before another spacecraft reaches Pluto to help confirm these findings. In the meantime, the case for Pluto’s interior ocean grows stronger!

Further Reading: Washington University at St. Louis, Icarus

The post Pluto Has an Ocean of Liquid Water Surrounded by a 40-80 km Ice Shell appeared first on Universe Today.

The earliest black holes in the Universe called primordial black holes (PBHs), are strong contenders to help explain why the Universe is heavier than it looks. There’s only one problem: these miniature monsters haven’t exactly been observed—yet. But, when astronomers do find them, they might turn out to be part of the Universe’s dark matter component.

Primordial black holes are one of several types of highly massive objects thought to exist in the Universe. We already know about stellar-mass black holes. They form during the deaths of hugely massive stars and generally end up containing up to dozens of solar masses. Then there are the supermassive black holes, embedded in the hearts of most galaxies. They sequester up to millions of solar masses.

The intermediate-mass black holes occupy the middle of the “black hole” spectrum. They’re another hot topic in black hole research circles. Appropriately enough, the masses of these black holes are between their stellar and supermassive counterparts. All these types of massive objects can collide with each other to grow bigger black holes. That generates gravitational waves that can be detected. The “ping” of each gravitational wave tells scientists a great deal about the objects colliding, including their masses.

How we might discover primordial black holes and help solve the dark matter mystery. Credit: ESA Understanding Primordial Black Holes in Context of Cosmic History

While astronomers search for PHBs, others are looking to explain why they might be part of the dark matter component of the Universe. In addition, they could explain the origin of binary black holes detected in gravitational wave observations.

A team of researchers at the University of Tokyo examined the “problem” of PBHs. Their work suggests that there should be far fewer of these objects than current models show. But, nobody knows how many existed back then. So, astronomers search them out using gravitational wave observatories. Their discovery should open a window on conditions in the early Universe when PBH formed.

These miniature ones are fascinating to think about. “Many researchers feel they are a strong candidate for dark matter, but there would need to be plenty of them to satisfy that theory,” said graduate student and team member Jason Kristiano. “They are interesting for other reasons too, as since the recent innovation of gravitational wave astronomy, there have been discoveries of binary black hole mergers, which can be explained if PBHs exist in large numbers. But despite these strong reasons for their expected abundance, we have not seen any directly, and now we have a model which should explain why this is the case.”

Modeling the Existence of Primordial Black Holes

The big question about PHBs: do (or did) they exist? And, can they be part of the dark matter component of the Universe? To answer that, Kristiano and his advisor Jun’ichi Yokoyama, searched through models of PBH formation. The best ones do not agree with the observed conditions of the leftover light fingerprint of the Big Bang. That’s called the cosmic microwave background (CMB). This is important, since PBHs formed in very early epochs of cosmic history, soon after the Big Bang. So, the team used the best model of PBH formation and applied quantum field theory to bring the model into alignment with reality.

Yokoyama explained the background behind their work. “At the beginning, the universe was incredibly small, much smaller than the size of a single atom. Cosmic inflation rapidly expanded that by 25 orders of magnitude. At that time, waves traveling through this tiny space could have had relatively large amplitudes but very short wavelengths. What we have found is that these tiny but strong waves can translate to otherwise inexplicable amplification of much longer waves we see in the present CMB,” said Yokoyama.

“We believe this is due to occasional instances of coherence between these early short waves, which can be explained using quantum field theory, the most robust theory we have to describe everyday phenomena such as photons or electrons. While individual short waves would be relatively powerless, coherent groups would have the power to reshape waves much larger than themselves. This is a rare instance of where a theory of something at one extreme scale seems to explain something at the opposite end of the scale.”

From Fluctuations to Miniature Black Holes

Those early small-scale fluctuations Yokohama describes affect some of the larger-scale fluctuations in the cosmic microwave background. Researchers can use measurements of wavelengths in the CMB to constrain the extent of corresponding wavelengths in the early Universe. That also puts some limits on any other phenomena that rely on the shorter, stronger wavelengths. And this is where the PBHs come back in.

“It is widely believed that the collapse of short but strong wavelengths in the early universe is what creates primordial black holes,” said Kristiano. “Our study suggests there should be far fewer PBHs than would be needed if they are indeed a strong candidate for dark matter or gravitational wave events.”

The next step relies on gravitational wave observatories and other types of observations. LIGO in the U.S., Virgo in Italy and KAGRA in Japan, are cooperating in observations aimed at finding the first PHBs. The results should help refine the ideas from Yokoyama’s team about PHBs and dark matter.

For More Information

The Case of the Missing Black Holes
Constraining Primordial Black Hole Formation from Single-Field Inflation
Note on the Bispectrum and One-loop corrections in Single-field Inflation with Primordial Black Hole Formation

The post Where are All the Primordial Black Holes? appeared first on Universe Today.

Boeing's Starliner capsule rolled out to the pad today (May 30) ahead of its first-ever astronaut launch, which is scheduled for June 1.

Featured in this new image from the NASA/ESA/CSA James Webb Space Telescope is the dwarf galaxy NGC 4449. This galaxy, also known as Caldwell 21, resides roughly 12.5 million light-years away in the constellation Canes Venatici. NGC 4449 has been forming stars for several billion years, but it is currently experiencing a period of star formation at a much higher rate than in the past. Such unusually explosive and intense star formation activity is called a starburst and for that reason NGC 4449 is known as a starburst galaxy. Starbursts usually occur in the central regions of galaxies, but NGC 4449 displays more widespread star formation activity, and the very youngest stars are observed both in the nucleus and in streams surrounding the galaxy. It's likely that the current widespread starburst was triggered by interaction or merging with a smaller companion; indeed, astronomers think NGC 4449's star formation has been influenced by interactions with several of its neighbors.

The Japanese space agency has lost contact with its intrepid Venus orbiter, Akatsuki.