Exoplanets' climate – it takes nothing to switch from habitable to hell

Runaway greenhouse effect can transform a temperate habitable planet with surface liquid water ocean into a hot steam dominated planet hostile to any life
Image Credit: (Chaverot et al., 2023). © Thibaut Roger / UNIGE

The Earth is a wonderful blue and green dot covered with oceans and life, while Venus is a yellowish sterile sphere that is not only inhospitable but also sterile. However, the difference between the two bears to only a few degrees in temperature. A team of astronomers from the University of Geneva (UNIGE), with the support of the CNRS laboratories of Paris and Bordeaux, has achieved a world’s first by managing to simulate the entirety of the runaway greenhouse process which can transform the climate of a planet from idyllic and perfect for life, to a place more than harsh and hostile. The scientists have also demonstrated that from the initial stages of the process, the atmospheric structure and cloud coverage undergo significant changes, leading to an almost-unstoppable and very complicated to reverse runaway greenhouse effect. On Earth, a global average temperature rise of just a few tens of degrees, subsequent to a slight rise of the Sun’s luminosity, would be sufficient to initiate this phenomenon and to make our planet inhabitable. These results are published in Astronomy & Astrophysics.

Long-sought binary star population found! Discovery could answer questions about hydrogen-poor supernova origins

An artist’s conception of the hydrogen being stripped from one half of a binary system, leaving a very hot, helium rich exposed core that will eventually explode as a hydrogen-poor core collapse supernova.
 Illustration Credit: Navid Marvi, courtesy of the Carnegie Institution for Science.

A team of astronomers has found a long- “missing” population of stars that could answer long-standing questions about the origins of a mysterious type of supernova. Their discovery, published in Science, could help researchers understand how hydrogen-poor core-collapse supernovae and neutron star collisions occur—major stellar events that are the source of many of the elements on the periodic table.

The project’s leaders, the University of Toronto’s Maria Drout and the Institute of Science and Technology Austria’s Ylva Götberg, met as junior researchers, and both went on to complete postdoctoral positions at the Carnegie Observatories—where the majority of this work was done—and have since moved onto assistant professor positions at their respective institutions.

Supernovae are violent stellar explosions that spew material into their cosmic surroundings, seeding the next generation of stars. But astronomers are still working to elucidate how they originate and what their various stellar progenitors look like—which differ between types of supernovae.

Drout and Götberg were particularly interested in one type of supernovae that stands out from their celestial peers for being hydrogen poor.

Ryugu Samples Illuminate Terrestrial Weathering Effects on Primitive Meteorites

Optical images of the Ryugu sample (left) and the CI chondrite (Orgueil ; right).
Image Credit: ©Kana Amano et al.

A groundbreaking study conducted by a team of international scientists has unveiled unprecedented insights into the nature of the asteroid Ryugu and shed light on the composition of water- and carbon-rich small bodies in the solar system.

Asteroids like Ryugu are remnants of planetary embryos that never reached larger sizes, making them invaluable windows into materials that formed in the early solar system. The study centered on laboratory measurements of the samples brought back to the Earth by the Hayabusa2 spacecraft in 2020. Led by the Japan Aerospace Exploration Agency (JAXA), Hayabusa2 aimed to uncover the true nature of Ryugu and explore how astrologists can use knowledge from meteorites to interpret telescopic observations of other hydrous asteroids.

Unlike meteorites derived from similar hydrous asteroids, the Ryugu samples avoided terrestrial alteration - the interaction with oxygen and water in the Earth's atmosphere.

Mystery Resolved: Black Hole Feeding and Feedback at the Center of an Active Galaxy

Fig. 1
An illustration depicting the distribution of interstellar medium in the active galactic nucleus based on the results of this observation.
Illustration Credit: ©ALMA (ESO/NAOJ/NRAO), T. Izumi et al.

An international research team led by Takuma Izumi, an assistant professor at the National Astronomical Observatory of Japan, has observed in high resolution (approximately 1 light year) the active galactic nucleus of the Circinus Galaxy - one of the closest major galaxies to the Milky Way. The observation was made possible by the Atacama Large Millimeter/Submillimeter Array (ALMA) astronomical observatory in Chile.

This breakthrough marks the world's first quantitative measurement at this scale of gas flows and their structures of a nearby supermassive black hole in all phase gases, including plasma, atomic, and molecular. Such high resolution allowed the team to team to capture the accretion flow heading towards the supermassive black hole, revealing that this accretion flow is generated by a physical mechanism known as 'gravitational instability.' Furthermore, the team also found that a significant portion of this accretion flow does not contribute to the growth of the black hole. Instead, most of the gas is expelled from the vicinity of the black hole as atomic or molecular outflows, and returns to the gas disk to participate again into an accretion flow towards the black hole, much like how water gets recycled in a water fountain. These findings represent a crucial advancement towards a greater understanding of the growth mechanisms of supermassive black holes.

Jurassic worlds might be easier to spot than modern Earth

Modeling by Cornell astronomers finds that telescopes could more easily detect an exoplanet with higher levels of atmospheric oxygen than modern Earth, as existed during the dinosaur age.
Illustration Credit: Rebecca Payne/Carl Sagan Institute

Might a tyrannosaur roam on Trappist-1e, a protoceratops on Proxima Centauri b, or a quetzalcoatlus on Kepler 1047c?

Things may not have ended well for dinosaurs on Earth, but Cornell astronomers say the “light fingerprint” of the conditions that enabled them to emerge here – including abundant atmospheric oxygen – provides a crucial missing piece in our search for signs of life on planets orbiting other stars.

Modeling by Cornell astronomers finds that telescopes could more easily detect an exoplanet with higher levels of atmospheric oxygen than modern Earth, as existed during the dinosaur age.

Their analysis of the most recent 540 million years of Earth’s evolution, known as the Phanerozoic Eon, finds that telescopes could better detect potential chemical signatures of life in the atmosphere of an Earth-like exoplanet more closely resembling the age the dinosaurs inhabited than the one we know today.

Two key biosignature pairs – oxygen and methane, and ozone and methane – appeared stronger in models of Earth roughly 100 million to 300 million years ago, when oxygen levels were significantly higher. The models simulated the transmission spectra, or light fingerprint, generated by an atmosphere that absorbs some colors of starlight and lets others filter through, information scientists use to determine the atmosphere’s composition.

The Remains of an Ancient Planet Lie Deep Within Earth

Video Credit: California Institute of Technology

In the 1980s, geophysicists made a startling discovery: two continent-sized blobs of unusual material were found deep near the center of the Earth, one beneath the African continent and one beneath the Pacific Ocean. Each blob is twice the size of the Moon and likely composed of different proportions of elements than the mantle surrounding it.

Where did these strange blobs—formally known as large low-velocity provinces (LLVPs)—come from? A new study led by Caltech researchers suggests that they are remnants of an ancient planet that violently collided with Earth billions of years ago in the same giant impact that created our Moon.

The study, published in the journal Nature on November 1, also proposes an answer to another planetary science mystery. Researchers have long hypothesized that the Moon was created in the aftermath of a giant impact between Earth and a smaller planet dubbed Theia, but no trace of Theia has ever been found in the asteroid belt or in meteorites. This new study suggests that most of Theia was absorbed into the young Earth, forming the LLVPs, while residual debris from the impact coalesced into the Moon.

Meteors Can Be Affected by Massive Objects Within and Near the Solar System

Superimposed images of FH1 flight recorded in Finland.
Photo Credit: Maria Gritsevich

Apparently interstellar meteors may be the result of accelerated meteoroid collisions with massive objects passing near or through the Solar System. This was reported by Maria Gritsevich, Associate Professor at the University of Helsinki and Senior Researcher at the Ural Federal University, at the VII Workshop on Robotic Autonomous Observatories in Malaga, Spain.

The conclusion, announced by Maria Gritsevich at the workshop as co-author of a paper and scientific article published in the journal Icarus, is due to the study of meteor FH1. This is an astronomical event registered by the Finnish Fireball Network on October 23, 2022. The speed of FH1 exceeded the speed of objects within the solar system. Thus, FH1 could be both an object in the Oort Cloud, a theoretical spherical region - the source of long-period comets - at the edge of the Solar System, and an interstellar object.

"According to our hypothesis, the trajectory of the FH1 meteoroid could have been affected by the passage of the so-called Scholz star - a double star system - close to the Sun. This event is estimated to have occurred several tens of thousands of years ago, and the gravitational perturbations caused by it changed the orbit of the meteoroid", explains Maria Gritsevich.

Giant planets cast a deadly pall

Artist's depiction of a star system that is crowded with giant planets.
Illustration Credit: NASA/Dana Berry

Giant gas planets can be agents of chaos, ensuring nothing lives on their Earth-like neighbors around other stars. New studies show, in some planetary systems, the giants tend to kick smaller planets out of orbit and wreak havoc on their climates. 

Jupiter, by far the biggest planet in our solar system, plays an important protective role. Its enormous gravitational field deflects comets and asteroids that might otherwise hit Earth, helping create a stable environment for life. However, giant planets elsewhere in the universe do not necessarily protect life on their smaller, rocky planet neighbors. 

A new Astronomical Journal paper details how the pull of massive planets in a nearby star system are likely to toss their Earth-like neighbors out of the “habitable zone.” This zone is defined as the range of distances from a star that is warm enough for liquid water to exist on a planet’s surface, making life possible.

Unlike most other known solar systems, the four giant planets in HD 141399 are farther from their star. This makes it a good model for comparison with our solar system where Jupiter and Saturn are also relatively far from the sun.  

“It’s as if they have four Jupiters acting like wrecking balls, throwing everything out of whack,” said Stephen Kane, UC Riverside astrophysicist and author of the journal paper. 

Venus had Earth-like plate tectonics billions of years ago

Photo Credit: NASA/JPL

A new study found that Venus, a scorching wasteland of a planet according to scientists, may have once had tectonic plate movements similar to those believed to have occurred on early Earth, a new study found. The finding sets up tantalizing scenarios regarding the possibility of early life on Venus, its evolutionary past and the history of the solar system.

Writing in Nature Astronomy, a team of scientists led by Brown University researchers describes using atmospheric data from Venus and computer modeling to show that the composition of the planet’s current atmosphere and surface pressure would only have been possible as a result of an early form of plate tectonics, a process critical to life that involves multiple continental plates pushing, pulling and sliding beneath one another.

On Earth, this process intensified over billions of years, forming new continents and mountains, and leading to chemical reactions that stabilized the planet’s surface temperature, resulting in an environment more conducive to the development of life.

Deep learning speeds up galactic calculations

A more efficient simulation.
During a supernova simulation, (left) shows the prediction by a current simulation method. (right) shows the prediction by 3D-MIM, which looks close enough to the that of the current leading method, but it takes far less time to execute, saving time, energy and costs for computing time.
Image Credit: ©2023 Hirashima et al.
(CC-BY-ND)

Supernovae, exploding stars, play a critical role in the formation and evolution of galaxies. However, key aspects of them are notoriously difficult to simulate accurately in reasonably short amounts of time. For the first time, a team of researchers, including those from The University of Tokyo, apply deep learning to the problem of supernova simulation. Their approach can speed up the simulation of supernovae, and therefore of galaxy formation and evolution as well. These simulations include the evolution of the chemistry which led to life.

When you hear about deep learning, you might think of the latest app that sprung up this week to do something clever with images or generate humanlike text. Deep learning might be responsible for some behind-the-scenes aspects of such things, but it’s also used extensively in different fields of research. Recently, a team at a tech event called a hackathon applied deep learning to weather forecasting. It proved quite effective, and this got doctoral student Keiya Hirashima from the University of Tokyo’s Department of Astronomy thinking.

A molten layer at the base of the Martian mantle ?

Artist view of Mars interior structure showing a molten layer at the base of the mantle and above the core. The purple line shows the path followed in Mars by the waves generated by the meteorite impact that occurred on September 2021 and diffracted along the CMB. The blue line represents the path followed by a seismic wave reflected at the top of the molten basal layer.
Illustration Credits: CNES/IPGP.

The analysis, by a team of scientists involved in the InSight mission, of seismic data recorded on Mars after a meteorite impact that occurred in September 2021 drastically changes our view of the internal structure and evolution of the Red Planet. Based on these results and previous geophysical data, a study published on October 26 in the journal Nature, in which researcher Attilio Rivoldini from the Royal Observatory of Belgium participated, proposes a new model for the interior of Mars, with a heterogeneous mantle containing a molten silicate layer above the liquid metal core.

The first results based on data from the InSight mission significantly improved our knowledge of the interior structure of Mars. Assuming that the mantle is compositionally homogeneous and entirely solid, the results showed that the liquid metal core has a radius of about 1830±40 km and a relatively low density (6-6.2 g/cm3) with a large concentration of light elements. The size of the metal core was determined by the detection of seismic waves reflected at a solid-liquid interface ascribed to be the Core-Mantle Boundary (CMB).

UrFU Scientists Registered a Meteorite Weighing Almost 300 Kilograms

Kapustin Yar meteorite
Photo Credit: Courtesy of Ural Federal University

Scientists from the Institute of Geology and Mineralogy of the Siberian Branch of the Russian Academy of Sciences and the Extra Terra Consortium laboratory of UrFU have registered a new meteorite (chondrite) in the Meteoritical Bulletin Database of the International Meteoritical Society. The chondrite was named "Kapustin Yar" (Capustin Yar). It was one of 29 L/LL6 class meteorites found on Earth and the heaviest of the group.

"The total weight of the meteorite is 276.5 kg. The main mass is still in Volgograd, fragments - in Novosibirsk and Moscow. The largest sample of meteorite measuring 48×60×50 cm has an angular and slightly rounded shape. Its surface is partially covered with fusion crust, which is also characteristic of smaller fragments. The name "Kapustin Yar" was given by the gunnery range of the same name in the Astrakhan region, because near the place of the meteorite fall and around this test site there are no residential settlements. So far, the Kapustin Yar chondrite is the third meteorite found in the Astrakhan region," says Viktor Sharygin, a senior researcher at the Extra Terra Consortium laboratory of UrFU.

Scientists and philosophers team up to study concept of evolution beyond biological context

As Earth formed, new geologic processes, especially those related to the interaction of hot fluids with rock during igneous activity and plate tectonics, gave birth to over 1500 new mineral species (4.55 to 2.5 billion years ago). At 2.5 billion years ago, emerging biological life introduced oxygen into the atmosphere. This was a time of pivotal change, when photosynthesis began and the interaction of iron with oxygen-based minerals changed ancient life, providing the blueprint for our future evolution, together with minerals. With the progress of the evolution of life from single-celled to multicelled organisms, and the formation of ecosystems, the mineralogy of the surface of the earth became more complex. The mineral diversity that was created fundamentally changed the direction and possibilities of evolution. Biodiversity leads to mineral diversity, and vice versa. The two systems, biological and mineral, interacted to create life as we know it today
Photo Credit: Dr. Robert Lavinsky

A new paper from an interdisciplinary team led by Carnegie’s Michael Wong and Robert Hazen explores the idea of increasing complexity in natural systems through the lens of evolution. Their work, published by Proceedings of the National Academy of Sciences hypothesizes the existence of “a missing law of nature.”

Their work proposes that complex natural systems evolve to states of greater patterning, diversity, and complexity. In other words, they say that evolution is not limited to life on Earth, it also occurs in other massively complex systems, from planets and stars to atoms, minerals, and more.

Authored by a nine-member team—scientists from Carnegie, Caltech, and Cornell University, and philosophers from the University of Colorado—the work was funded by the John Templeton Foundation.

“Macroscopic” laws of nature describe and explain phenomena experienced daily in the natural world. Natural laws related to forces and motion, gravity, electromagnetism, and energy, for example, were described more than 150 years ago.

A new lens” into the Universe’s most energetic particles

An example of a cosmic-ray extensive air shower recorded by the Subaru Telescope. The highlighted tracks, which are mostly aligned in similar directions, show the shower particles induced from a high-energy cosmic ray. 
Image Credit: National Astronomical Observatory of Japan, Hyper Suprime-Cam (HSC) Collaboration

Showers in bathrooms bring us comfort; showers from space bring astrophysicists joy. Osaka Metropolitan University scientists have observed, with their novel method, cosmic-ray extensive air showers with unprecedented precision, opening the door to new insights into the Universe’s most energetic particles.

When a high energy cosmic ray collides with the Earth's atmosphere, it generates an enormous number of particles known as an extensive air shower. A research team led by Associate Professor Toshihiro Fujii from the Graduate School of Science and Nambu Yoichiro Institute of Theoretical and Experimental Physics at Osaka Metropolitan University, along with graduate student Fraser Bradfield, has discovered that the prime-focus wide field camera mounted on the Subaru Telescope, situated atop the Mauna Kea volcano in Hawaii, can capture these extensive air showers with extremely high resolution.

“Starquakes” could explain mystery signals

Earthquake map. Data on earthquakes was taken from Japan’s Kanto region (including Tokyo and Narita) and Izumo in the Chugoku region (north of Hiroshima). Black dots represent the epicenters of earthquakes recorded between May 6, 2010, and December 31, 2012.
Image Credit: ©2023 T. Totani & Y. Tsuzuki

Fast radio bursts, or FRBs, are an astronomical mystery, with their exact cause and origins still unconfirmed. These intense bursts of radio energy are invisible to the human eye, but show up brightly on radio telescopes. Previous studies have noted broad similarities between the energy distribution of repeat FRBs, and that of earthquakes and solar flares. However, new research at the University of Tokyo has looked at the time and energy of FRBs and found distinct differences between FRBs and solar flares, but several notable similarities between FRBs and earthquakes. This supports the theory that FRBs are caused by “starquakes” on the surface of neutron stars. This discovery could help us better understand earthquakes, the behavior of high-density matter and aspects of nuclear physics.

The vastness of space holds many mysteries. While some people dream of boldly going where no one has gone before, there is a lot we can learn from the comfort of Earth. Thanks to technological advances, we can explore the surface of Mars, marvel at Saturn’s rings and pick up mysterious signals from deep space. Fast radio bursts are hugely powerful, bright bursts of energy which are visible on radio waves. First discovered in 2007, these bursts can travel billions of light years but typically last mere thousandths of a second. It has been estimated that as many as 10,000 FRBs may happen every day if we could observe the whole sky. While the sources of most bursts detected so far appear to emit a one-off event, there are about 50 FRB sources which emit bursts repeatedly.

Removal of magnetic spacecraft contamination within extraterrestrial samples easily carried out

PhD student Ji-In Jung, left, and Assistant Professor Sonia Tikoo examine a collection of lunar samples.
 Photo Credit: Harry Gregory

By demonstrating that spaceflight doesn’t adversely affect the magnetism of moon rocks, Stanford researchers underscore the exciting potential of studying the magnetic histories stored in these samples.

For decades, scientists have pondered the mystery of the moon’s ancient magnetism. Based on analyses of lunar samples, its now-deceased magnetic field may have been active for more than 1.5 billion years – give or take a billion years. Scientists believe it was generated like the Earth’s via a dynamo process, whereby the spinning and churning of conductive liquid metal within a rocky planet’s core generates a magnetic field. However, researchers have grappled with how such a small planetary body could have sustained a long-lived magnetic field. Some have even questioned the legitimacy of return samples that point to the existence of an ancient dynamo, suggesting magnetism may have been acquired via exposure to strong magnetic fields onboard spacecraft during the return mission or from plasmas produced by massive impacts on the moon.

Stanford University scientists have now demonstrated that the magnetism in lunar samples is not adversely altered by the spacecraft journey back to Earth or certain laboratory procedures, disproving one of the two major oppositions to the ancient dynamo theory. The findings, published in Geophysical Research Letters Oct. 11, bode well for research stemming from other sample-return missions from space, since any magnetic contamination acquired during flight or on Earth can likely be easily removed.

Lethal Climate Change Millions of Years Ago Was Due to Volcanic Eruptions, Scientists Conclude

Earth’s Geological History Tied to Astronomical Motions—Not Just the Planet’s Interior
Illustration Credit: Scientific Frontline

Climate change that has occurred over the past 260 million years and brought about mass extinctions of life during these periods was due to massive volcanic eruptions and subsequent environmental crises, concludes a team of scientists.

Its analysis, which appears in the journal Earth-Science Reviews, shows that these eruptions released large amounts of carbon dioxide into the Earth’s atmosphere, leading to extreme greenhouse climate warming and bringing about near-lethal or lethal conditions to our planet.

Significantly, these phenomena—which occur every 26 to 33 million years—coincided with critical changes in the planet’s orbit in the solar system that follow the same cyclical patterns, the researchers add.

“The Earth’s geologic processes, long considered to be strictly determined by events within the planet’s interior, may in fact be controlled by astronomical cycles in the solar system and the Milky Way Galaxy,” says Michael Rampino, a professor in New York University’s Department of Biology and the paper’s senior author. “Crucially, these forces have converged many times in the Earth’s past to foreshadow drastic changes to our climate.”

New Model Explains Precious Metals in Earth’s Mantle

Video Credit: Southwest Research Institute

Southwest Research Institute’s Dr. Simone Marchi collaborated on a new study finding the first geophysically plausible scenario to explain the abundance of certain precious metals — including gold and platinum — in the Earth’s mantle. Based on the simulations, or model, scientists found that impact-driven mixing of mantle materials scenario that could prevent the metals from completely sinking into the Earth’s core.

Early in its evolution, about 4.5 billion years ago, Earth sustained an impact with a Mars-sized planet, and the Moon formed from the resulting debris ejected into an Earth-orbiting disk. A long period of bombardment followed, the so-called “late accretion,” when planetesimals as large as our Moon impacted the Earth delivering materials including highly “siderophile” elements (HSEs) — metals with a strong affinity for iron — that were integrated into the young Earth.

“Previous simulations of impacts penetrating Earth’s mantle showed that only small fractions of a metallic core of planetesimals are available to be assimilated by Earth’s mantle, while most of these metals — including HSEs — quickly drain down to the Earth’s core,” said Marchi, who coauthored a Proceedings of the National Academy of Sciences (PNAS) paper outlining the new findings. “This brings us to the question: How did Earth get some of its precious metals? We developed new simulations to try to explain the metal and rock mix of materials in the present-day mantle.”

Astronomers Discover First Step Toward Planet Formation

An image of the radio wave strength at a wavelength of 1.3 mm of the disk around the star DG Taurus, observed with ALMA. Unlike older protostellar disks, ring-like structures have not yet formed, suggesting that the disk is at the stage just before planet formation.
Image Credit: ALMA (ESO/NAOJ/NRAO), S. Ohashi et al.

An international research team led by Project Assistant Professor Satoshi Ohashi of the National Astronomical Observatory of Japan (NAOJ) has conducted high-resolution and multi-wavelength observations of a protoplanetary disk around a relatively young protostar, DG Taurus (DG Tau), using ALMA* to study the structure of the disk and the size and amount of dust, the material for planets. Associate Professor Okuzumi from Tokyo Institute of Technology (Tokyo Tech) participated in this research as a team member. As a result, the team succeeded in capturing the conditions on the eve of planet formation, as the disk was smooth with no signature of planets. They also found that the dust had grown significantly in the outer part of the disk and that the dust concentration was higher than normal in the inner part of the disk. With these results, the first step in the process of planet formation has been revealed.

Study suggests large mound structures on Kuiper belt object Arrokoth may have common origin

The large mound structures that dominate one of the lobes of the Kuiper belt object Arrokoth are similar enough to suggest a common origin, according to a new study led by Southwest Research Institute (SwRI) Planetary Scientist and Associate Vice President Dr. Alan Stern.
Graphic Credit: Courtesy of SwRI

A new study led by Southwest Research Institute (SwRI) Planetary Scientist and Associate Vice President Dr. Alan Stern posits that the large, approximately 5-kilometer-long mounds that dominate the appearance of the larger lobe of the pristine Kuiper Belt object Arrokoth are similar enough to suggest a common origin. The SwRI study suggests that these “building blocks” could guide further work on planetesimal formational models. Stern presented these findings this week at the American Astronomical Society’s 55th Annual Division for Planetary Sciences (DPS) meeting in San Antonio. These results are now also published in the peer-reviewed Planetary Science Journal.

NASA’s New Horizons spacecraft made a close flyby of Arrokoth in 2019. From those data, Stern and his coauthors identified 12 mounds on Arrokoth’s larger lobe, Wenu, which are almost the same shape, size, color and reflectivity. They also tentatively identified three more mounds on the object’s smaller lobe, Weeyo..