Two teams of astronomers independently discovered a third giant gas planet orbiting in the famous Beta Pictoris system.
The post Famous System Has a Third Planet: Beta Pictoris d appeared first on Sky & Telescope.
It has taken over ten years, but astronomers have finally won a prolonged game of cosmic hide-and-seek with a planet hiding around the star Beta Pictoris. The extrasolar planet, or exoplanet, is known as Beta Pictoris d. It is found 63 light-years away and has two planetary siblings, which were caught some time ago.
This new exoplanet is 100 times fainter than its sibling Beta Pictoris b, which was the first planet discovered in the system. That makes Beta Pictoris d the faintest exoplanet ever seen from Earth.
Like its previously discovered sibling, Beta Pictoris d is a gas giant. However, unlike Beta Pictoris b and Beta Pictoris c, it is much further away from its parent star and is thus much cooler than its siblings. The newly discovered world is also smaller than the previously seen world around Beta Pictoris. While both Beta Pictoris b and Beta Pictoris c have around 10 times the mass of Jupiter each, Beta Pictoris d has only around 2.4 times the mass of the solar system's most massive world. That makes it one of the lightest exoplanets ever directly imaged by a ground-based telescope.
"Planet d, it seems, has been playing a game of hide-and-seek with us for over a decade, and only now can we say ‘found you!’" team member Jayne Birkby an astronomer at the University of Oxford in the UK, said in a statement.
The discovery of Beta Pictoris d helps clear up a puzzle regarding a disk of dust and debris in this planetary system, which is theorized to be made of the leftovers of planet formation. That is because this newly found world has exactly the right mass and location needed to explain both the odd shape of this debris disk and its location.
The team behind this discovery wasn't initially looking for a third planet around Beta Pictoris. Instead, they were simply attempting to learn more about the system's first planet.
"This was a serendipitous discovery," team co-leader Ben Sutlieff, an astronomer at the University of Edinburgh said. "We initially wanted to look more at a known planet in the system, Beta Pictoris b, to see how it changed over time."
That was until they spotted telltale signs of another planet around the same star. Delving back into 11 years of archival data, the team found the third planet lurking in various images.
To consider how impressive it is to directly image a planet outside the solar system, consider that of the over 6,000 worlds in NASA's exoplanet catalog, less than 100 were discovered using direct imaging. Such detections are so tricky because they require picking out the thermal glow of a planet from the glare of its parent star.
Catching a direct image of an exoplanet as faint as Beta Pictoris d is a major step forward for this technique.
"The new planet is 100 times fainter than Beta Pictoris b, the famous planet in the same system, making it the faintest exoplanet ever imaged directly from Earth," team co-leader and European Southern Observatory researcher Markus Bonse said.
The discovery of Beta Pictoris d makes the Beta Pictoris system just the second in which more than two worlds have been directly imaged. The first was HR 8799, which is located around 133 light-years away.
"Systems with multiple directly imaged exoplanets are the 'holy grails' of discoveries, because they can teach us a lot about what different exoplanets are like in the same formation environment," Sutlieff said
Thus, the discovery of Beta Pictoris d via direct imaging should encourage further direct imaging of planetary systems which may also harbor faint planets. This is an investigation that could be picked up by the Extremely Large Telescope (ELT), currently under construction in the Atacama Desert of northern Chile.
"Planets seem to have friends," team member Beth Biller, of the University of Edinburgh in the UK, said. "Many of the famous directly imaged exoplanet systems seem to have multiple giant planets in the same system, and likely there are even more lower-mass planets hiding in these systems that might be revealed with instruments on the ELT."
The team's research was published on Wednesday (July 15) in The Astrophysical Journal Letters.
"Rogue" Neptune-size worlds might not roam the galaxy totally on their own, just very far away from their parent stars.
The post "Rogue" Neptunes Are Detached But Not Alone appeared first on Sky & Telescope.
Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.
Title: Carbon Cycle Imbalances on Arid Terrestrial Planets with Implications for Venus
Authors: Haskelle T. White-Gianella and Joshua Krissansen-Totton
Authors’ Institution: University of Washington
Status: Published in PSJ
When discussing the habitability of planets, we usually focus on the habitable zone, the region around a star where a planet can host a temperature suitable for supporting liquid water on its surface. Yet, being in the right place doesn’t necessarily guarantee that a planet will be habitable.
A planet also needs the right atmospheric composition to sustain the necessary temperatures for hosting liquid water. A key mechanism found on Earth for maintaining this composition is the geologic carbon cycle, which acts as a built-in climate control system. This cycle begins with volcanic eruptions releasing carbon dioxide (CO2), which then dissolves in rainwater and forms a weak acid that weathers rocks on continents. The weathering products wash into oceans, where they form carbonate rocks, locking carbon away. Eventually, plate tectonics recycles some of that carbon back to volcanoes. The weathering process works faster when the planet is warmer, thus regulating the amount of CO2 and stabilizing the climate over long periods of time (but it should be noted that it can take up to a few hundred thousand years to rebalance this slow carbon cycle through the weathering process).
An important caveat is that the weathering process requires sufficient liquid water on the planet’s surface, so what happens in the case for planets with shallower oceans? Low-mass M dwarfs, the most common type of star found in the galaxy, are expected to host less-massive disks and therefore lower water inventories for forming planets. If more “dry” planets are indeed a more likely outcome of planet formation, we’d want to know how their arid conditions influence their long-term evolution and habitability.
The authors built a model that tracks how water and CO2 move between a planet’s interior, oceans, and atmosphere over 4.5 billion years. The model notably includes the following:
The model tests for four initial surface water inventories (0.1%, 1%, 10%, and 100% of Earth’s oceans) and then simulates how the surface water, atmosphere, and climate evolve over time.
The models reveal that planets require at least 20–50% of Earth’s ocean mass to maintain a balanced carbon cycle. Below this threshold, the carbon cycle becomes unbalanced, leading to devastating consequences for habitability (Figure 1).
Figure 1: Final surface temperature after simulating 4.5 billion years of evolution as a function of initial water inventory for Earth-like planets. Each dot represents a model run with different assumptions (total carbon inventory, temperature dependence of weathering, soil age, etc.). The yellow region shows where most simulations result in uninhabitable surface temperatures from an unbalanced carbon cycle, and the cyan region shows where most simulations result in habitable surface temperatures and a balanced carbon cycle. The left and right plots show the results for two different parameterizations of the deep water cycle implemented in the model. [White-Gianella & Krissansen-Totton 2026]
Looking within the solar system, the results offer an explanation for how a potentially habitable Venus could have transitioned into its current inhospitable state. If Venus had formed with an initial water inventory below this critical threshold of 20–50% of Earth’s ocean mass, then its carbon cycle would have become unbalanced, creating the CO2 inferno seen on Venus today.
In future exoplanet studies, telescopes like the Habitable Worlds Observatory might detect ocean glint (specular reflection from liquid water) or measure land fraction from light curves. Finding a planet in the habitable zone but with limited ocean coverage would likely be bad news, as the planet could be quietly losing its grip on habitability. Astronomers may want to be more careful when looking at seemingly promising planets within their habitable zones.
Original astrobite edited by Natalie Price.
About the author, Jared Bull:
I am a 2nd-year PhD student at Johns Hopkins University. I study brown-dwarf variability and am interested in using time-series observations to uncover dynamic processes within their atmospheres. In my free time I like to read, cook, and do astrophotography.
The post Can Arid Planets Keep Their Cool? appeared first on AAS Nova.
Clouds formed from vaporized rock could create the ultimate thermal insulation on one of the most common types of exoplanets discovered so far — the sub-Neptunes — raising temperatures so high that these worlds' solid surfaces melt and turn into oceans of magma.
"This work takes us one step closer to answering the question of what these mysterious worlds are made from," said astronomer Luis Welbanks, of Arizona State University, in a statement.
Sub-Neptunes are planets larger than Earth but smaller than Neptune. They are especially mysterious since we do not have a world of this type in our solar system. They are thought to contain a rocky core surrounded by a deep atmosphere, but not much else is known about their composition and structure. Their atmosphere could be hydrogen-rich like Jupiter's, or it could be abundant with water vapor and carbon-based organic molecules. In some cases, they might even be habitable under the hycean world paradigm, wherein a thick hydrogen atmosphere encases a global ocean of liquid water.
The James Webb Space Telescope (JWST) is busy probing the atmosphere of several sub-Neptunes to try and learn more about their bulk composition because their atmosphere should be representative of what such planets are made from, but results so far have been inconclusive.
Atmospheres of sub-Neptunes are deep and dense, meaning crushing pressures close to the boundary between the atmosphere and the solid body of the world can turn minerals into vapor that forms clouds. These minerals include aluminium oxide, iron, magnesium silicate, manganese sulfide, potassium chloride, sodium sulfide and zinc sulfide.
Using detailed computer simulations, a team led by Sagnick Mukherjee of Arizona State University explored what effect these clouds could have on both the surface and atmosphere of a sub-Neptune.
They showed that when these mineral clouds form deep down, they act as efficient insulating blankets that trap heat (and lots of it) leaking out from the core of the planet.
"Among the sub-Neptunes currently being studied with JWST, we were amazed to find that cloud-driven heating can raise the temperature at the planet's atmosphere–interior boundary by roughly over 1,400 to 2,600 degrees Celsius [2,550–4,712 degrees Fahrenheit]," said Mukherjee.
At the same time, because heat is being prevented from escaping, the upper atmosphere cools noticeably.
With all that heat retained close to the surface, the rock begins to melt.
"For some of the planets we modeled, that extra heat is enough to melt the planet's surface, creating a magma ocean," said team-member Matthew Nixon of Arizona State University.
These potential magma planets include GJ 1214b, which orbits a red dwarf star 48 light-years away. At one time it was thought to be a cool water-world, but JWST's discovery in 2025 of metallic vapors and carbon-dioxide haze in GJ 1214b's atmosphere rule this out, and now it seems that its surface, undetectable beneath the thick atmosphere, could be completely molten.
However, the presence of magma oceans opens up possibilities for more complex atmospheric chemistry. Gas seeps out of the magma and diffuses into the atmosphere, in theory enriching it in oxygen, silicon hydride and silicon monoxide, while going the other way the magma absorbs ammonia, methane and water vapor from the atmosphere. In other words, the atmosphere becomes enriched by material from underground, while also becoming depleted in some gases that astronomers would expect to see in greater abundance.
This means that JWST's attempts to learn about the bulk composition of a sub-Neptune exoplanet from the spectrum of its atmosphere could be skewed by this exchange of gases between a magma ocean and the atmosphere. The extra heating deep down will also impact the future of these sub-Neptune planets, since the extra heat will keep their lower atmosphere bloated and prevent the planet from contracting over billions of years.
If the findings are correct, they could place a huge obstacle on sub-Neptunes being habitable. Even if the boundary between the atmosphere and solid body of the planet isn't hot enough to form magma, it would still render the surface too hot to support liquid water or life.
The findings were published on July 8 in Astrophysical Journal Letters.
WD 1856 b is the only confirmed case of a planet that survived the death of a Sun-like star. It’s a Jupiter-size world orbiting a white dwarf—the burned-out remnant of a Sun-like star. Now, a team of astronomers has used the James Webb Space Telescope to take a closer look at this planet for the first time, and what they found makes an already strange system even stranger.
WD 1856 b was an accidental discovery. Astronomers pointed the TESS observatory at a sample of roughly 2,000 white dwarfs in 2020. These stars are the remains of a Sun-like star that have already gone through a red-giant phase, leaving behind an Earth-size body that’s primarily composed of elements like carbon and oxygen. The TESS team was searching for small objects like comets or asteroids that might transit across the face of these dead stars.
What they found in the WD 1856 system was a gas giant. “As soon as they looked at it, they said, okay, that’s weird,” said Christopher O’Connor, a theoretical astrophysicist at Cornell University and co-author of the recent Nature study on WD 1856 b.
© NASA, ESA, CSA, R. Crawford
A recently discovered exoplanet only 25 light years away resembles our own planet a lot more than once thought.
The distant world, dubbed GJ 3378b, orbits inside the habitable zone of a red dwarf star — a type of star that is much smaller and cooler than our Sun — where temperatures are just right for liquid water to form on the surface.
But initially, its case for potentially supporting life beyond that looked grim. Astronomers suspected it was a rocky world, but its mass was at least five times more than Earth — or what astronomers called a “super-Earth.” Along with its incredible surface gravity, such a heavy world would possess a crushing atmosphere that would smother any chance of hosting life.
That no longer appears to be the case, however. In a new study published in The Astrophysical Journal, researchers from the University of California, Irvine, took a second look at the exoplanet, finding that it’s a much more manageable twice the mass of Earth. Combined with its proximity to our solar system, it’s one of the most tantalizing nearby candidates for potentially supporting life yet.
“This one’s exciting,” lead author Paul Robertson, a UC Irvine associate professor of astronomy, said in a statement about the work. “It’s one of our closest cosmic neighbors. 25 light-years sounds like a long way, but the Milky Way is about 100,000 light-years across, so in that respect it’s our next-door neighbor.”
There’s more detective work that needs to be done before we know how hospitable to life GJ 3378b is. The biggest question mark is its atmosphere. Does it have one, and is it robust enough to protect against the radiation of its star? And how much pressure does it exert?
It’s a delicate balance. “If you scale the Earth down to the size of an apple,” Robertson explained, “its atmosphere would be about as thick as the skin of the apple.” This is just the right amount to support liquid water and have breathable air, while still providing protection against space radiation, he added.
There’s also a raging debate in astronomy over whether red dwarf systems are habitable at all. These stars are believed to be highly volatile, regularly unleashing powerful solar flares. Because their habitable zones are smaller, that puts a potential life-supporting realm much closer to these outbursts, which could strip them of their atmosphere and sterilize any burgeoning life. Being so close to the star also means that any such planets are likely to be tidally locked, in which the star’s gravity prevents them from rotating so that one side is facing the star at all times.
More on space: Saturn’s Icy Moon Is the Perfect Place to Settle, NASA Scientist Argues
The post Scientists Say They’ve Identified an Earth-Like Planet Right Next Door appeared first on Futurism.
Microlensing surveys have discovered plenty of regular exoplanets, but more surprisingly, they’ve also turned up many solo Neptunes with no star nearby. New research suggests that first impressions might be deceiving, however, and that at least some of these planets might not be so alone: they just have a complicated family history.
There are simply too many Neptune-like exoplanets in our galaxy. Or at least that’s the current feeling astronomers get from gravitational microlensing surveys, which look for exoplanets during short-lived magnification events caused by chance alignments between stars. These surveys have now found about a dozen so-called “free-floating” planets, and while this doesn’t sound like that many, running the numbers reveals that this tiny sample implies that there are about two free-floating Neptune-size planets for every star in the galaxy.
An illustration of how exoplanets are found via microlensing. The broad first bump is caused by the host star magnifying the light from a background star; the narrow second bump is caused by the planet acting as a lens as well. “Free-floating” planets create only one bump. [Adapted from NASA, ESA, and A. Feild (STScI)]
However, new research by Sam Hadden (Canadian Institute for Theoretical Astrophysics) and Yanqin Wu (University of Toronto) presents an alternative idea: what if at least some of these free-floating planets aren’t fully on their own, but instead remain estranged but weakly bound to their parent stars?
Two celestial objects need to align nearly perfectly in order to create a microlensing pulse that we can detect. For an exoplanet orbiting a star, we should observe two of these pulses: one when the host star drifts in and out of alignment with a background star, and one when the nearby bound planet does the same. In the case of a free-floating planet, there’s only one pulse, and we therefore assume that there is no host star. Hadden and Wu noticed that since the alignment has to be so precise for microlensing to occur, it’s possible that a seemingly free-floating planet is simply widely separated from its host star, and the star managed to dodge the magnification effect. In other words, these planets might not be free floating at all, just on wide and eccentric orbits.
The orbital evolution of a five-planet system that undergoes planet–planet scattering. Each line represents one planet; note that in the end two are ejected, two end up on wide detached orbits, and the fifth ends up on a tightly bound inner orbit. Click to enlarge. [Hadden & Yu 2026]
They found that both types of simulations readily created the “detached” objects needed to mimic free-floating planets. In fact, the most common outcome was for two or three planets to be bullied into far-out orbits by a planet that then plunges onto a tight inner orbit extremely close to the star.
Though the authors caution that this process likely doesn’t explain all of the free-floating planets observed to date, this is an exciting model that would dramatically lower our estimates of the number of Neptunes roaming alone between the stars.
“Free Floating or Merely Detached?,” Sam Hadden and Yanqin Wu 2026 ApJ 1000 70. doi:10.3847/1538-4357/ae6508
The post Detached but Not Alone appeared first on AAS Nova.
Login