Tag: exoplanets

Astronomers discover two exoplanets as dense as cotton candy

9:40 am

The observed transits of TOI-791 c.
The observed transits of TOI-791 c by different telescopes
during its 232 day orbit. Figure 9 from the paper.

Using a combination of ground- and space-based telescopes, astronomers have now discovered two exoplanets in the same solar system that have a deas dense as cotton candy.

You can read their paper here. From the NASA press release:

Data from NASA’s TESS (Transiting Exoplanet Survey Satellite) mission has revealed two new “super-puff” planets, giant worlds so light that their density is comparable to cotton candy. Scientists calculate that these Jupiter-sized planets—named TOI-791 b and TOI-791 c—are the “puffiest” worlds ever found.

The planets orbit a Sun-like star named TOI-791 that is approximately 1,113 light years away from Earth. The TESS mission first detected the planets by watching for repeated dips in TOI-791’s brightness, a telltale sign that a planet is transiting, or passing in front of, a star. Further study revealed two large planets with unusual features.

TOI-791 b is nearly the same size as Jupiter but contains just 3.0 percent of Jupiter’s mass. TOI-791 c is even larger than Jupiter but contains just 5.9 percent of Jupiter’s mass.

The data for determining both planet’s density came from follow-up observations using a telescope based in Antarctica. Both planets have long orbits, 139 and 232 days respectively, so these observations took place over a period of eight years, in order to capture multiple orbital transits.

One interesting tidbit: Though the data suggests both planets are spherical, this is not confirmed with certainty. Overall, the nature of such puffy planets is not really understood at this time.

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The wind speeds on seven exoplanets also suggest presence of magnetic fields

10:54 am

Astronomers using two different ground-based telescopes were able to measure the wind speeds on seven different gas giant exoplanets, and found the speeds also suggested the presence of planetary magnetic fields, the first time such magnetic fields have been deduced on an exoplanet.

In the study, the researchers investigated the wind speeds on seven exoplanets orbiting different stars. These are gas giants similar to Jupiter, which are very close to their star. Elspeth Lee explains: “The rotation of the planets was synchronized with their orbits by the tidal forces of the parent star. Just as we only ever see one side of the moon, these planets always have one side facing the star. Thus, a glowing hot day side and a permanently dark night side have formed on the planets. The extreme temperature differences in turn lead to the generation of extremely strong winds.”

…The research team was able to show that wind speeds of around 7,200 km/h to over 25,000 km/h prevail on the exoplanets. For comparison: the fastest winds measured on Jupiter reach speeds of around 1,500 km/h.

The data showed that the hotter the planet, the slower the wind, the opposite of what was expected. The scientists believe that each planet’s magnetic field is acting to brake the winds, with the hotter planets likely having more powerful fields.

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Using Webb astronomers think they have detected daily weather changes on exoplanet

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The data confirming explanet's existence from 2014 paper
Figure 1 from the 2014 paper confirming exoplanet’s existence.

Using the Webb Space Telescope’s infrared spectroscopic data astronomers believe they have detected the daily weather changes on exoplanet WASP-94A b, a hot gas giant about half the mass of Jupiter that orbits its star every four days.

Observations revealed that mornings and evenings on WASP-94A b have extremely different weather patterns: Mornings are riddled with clouds made of magnesium silicate, a common mineral found in rocks, while the evening has clear skies.

The star itself is about 700 light years away, and is known to have two exoplanets circling it.

The scientists proposed two explanations for their data. Either strong winds are clearing the air in the evening, or the clouds are the equivalent of morning fog on Earth that naturally dissipates as the day brightens.

Note that there is great uncertainty with these results, as we are only getting a very limited view from 700 light years away. In a sense, our knowledge of these exoplanets is comparable to what we knew of our own solar system’s planets prior to the space age. Once we got our first close looks at the planets almost everything we thought we knew beforehand turned out to be either wrong or misguided, due to the limited nature of the data.

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Scientists compile catalog of the 69 known rocky exoplanets in the habitable zone

12:49 pm

Graph of the 45 most habitable known exoplanets
Credit: Gillis Lowry / Pablo Carlos Budassi.
Click for original at full resolution.

Scientists reviewing the more than 6,000 exoplanets so far discovered have now compiled a detailed catalog describing the 69 known rocky exoplanets that are also in the habitable zone.

The graph to the right, cropped and reduced to post here, shows the 45 exoplanets most likely to be habitable, with the amount of energy they get from their star measured relative to that of Earth and the Sun (shown center top). You can read their paper here. From the press release:

The researchers pinpointed 45 rocky worlds that may support life in the habitable zone, and another 24 in a narrower 3D habitable zone that makes a more conservative assumption of how much heat a planet can take before it loses its habitability.

They include some famous exoplanets, including Proxima Centauri b, TRAPPIST-1f and Kepler 186f, as well as others that are not as well known, such as TOI-715 b. The most interesting planets of those listed, according to the authors, are TRAPPIST-1 d, e, f and g, which are 40 light-years from Earth, as well as LHS 1140 b, which is 48 light-years away. Whether these planets could have liquid water depends in part if they can hold an atmosphere.

The worlds that get light from their stars most similar to what modern Earth receives from the Sun are the transiting planets TRAPPIST-1 e, TOI-715 b, Kepler-1652 b, Kepler-442 b, Kepler-1544 b and the planets Proxima Centauri b, GJ 1061 d, GJ 1002 b, and Wolf 1069 b, which make their stars wobble.

The paper includes tables listing the best exoplanets that do transits of their stars, the best with the oldest estimated ages, and the best for testing the limits of the habitable zone itself. As the researchers say in their abstract:

The resulting list of rocky exoplanet targets in the HZ will allow observers to shape and optimize search strategies with space- and ground-based telescopes – such as the James Webb Space Telescope (JWST), Extremely Large Telescope (ELT), Habitable Worlds Observatory (HWO), and Large Interferometer For Exoplanets (LIFE) – and design new observing strategies and instruments to explore these worlds, addressing the question of the limits of exoplanet surface habitability.

In other words, the focus of exoplanet research is now shifting from simply finding these planets to studying them directly, with the potentially habitable worlds listed above the most interesting of all. Astronomers might not find alien life or civilizations on these worlds, but at a minimum they will be doing the first preliminary scouting for humanity’s the first interstellar missions, with the Trappist-1 solar system appearing to head the list.

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Astronomers discover a super-Earth-sized exoplanet covered by a molten ocean of lava

9:53 am

Using the Webb Space Telescope astronomers think they have identified a super-Earth-sized exoplanet, dubbed L98-59d and orbiting a red dwarf star about 35 light years away, that is covered by a very deep molten ocean of lava.

Their results reveal that the mantle of L98-59d is likely molten silicate (similar to lava on Earth), with a global magma ocean extending thousands of kilometres beneath. This vast molten reservoir allows the planet to store extremely large amounts of sulphur deep inside its interior, over geologic timescales. The magma ocean also helps L98-59d to retain a thick hydrogen-rich atmosphere containing sulphur-bearing gases such as hydrogen sulphide (H2S). Normally, this would be lost to space over time, due to X-ray radiation produced by the host star.

You can read the peer-reviewed paper here [pdf]. This planet is part of a three-planet solar system, all of which transit the face of the star, allowing for excellent observations of their make-up. L98-59d is the outermost of the three.

This is the first molten exoplanet yet detected, though it is likely not the last. As new better telescopes come on-line both on Earth and especially in space, the ability to make more detailed observations of the thousands of exoplanets so far identified is certain to reveal many more strange objects, some of which will be probably far stranger than we can yet imagine.

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Have astronomers spotted the collision of two exoplanets around a Sunlike star?

9:36 am

Changes in the infrared

Using data from a number of orbiting space telescopes, astronomers think they have detected the collision of two exoplanets, producing debris that for about 200 days variably blocked the light from the system’s star.

The images to the right come from figure 1 of their published paper [pdf], showing changes in the infrared as detected by the WISE space telescope. From the press release:

The star, named Gaia20ehk, was about 11,000 light-years from Earth near the constellation Pupis. It was a stable “main sequence” star, much like our sun, which meant that it should emit steady, predictable light. Yet this star began to flicker wildly. “The star’s light output was nice and flat, but starting in 2016 it had these three dips in brightness. And then, right around 2021, it went completely bonkers,” said Tzanidakis, a doctoral candidate in astronomy at the University of Washington. “I can’t emphasize enough that stars like our sun don’t do that. So when we saw this one, we were like ‘Hello, what’s going on here?’”

The cause of the flickering had nothing to do with the star itself: Huge quantities of rocks and dust — seemingly from out of nowhere — were passing in front of the distant star as the material orbited the system, patchily dimming the light that reached Earth. The likely source of all that debris was even more remarkable: a catastrophic collision between two planets.

…“The infrared light curve was the complete opposite of the visible light,” Tzanidakis said. “As the visible light began to flicker and dim, the infrared light spiked. Which could mean that the material blocking the star is hot — so hot that it’s glowing in the infrared.”

A cataclysmic collision between planets would certainly produce enough heat to explain the infrared energy. What’s more, the right kind of collision could also explain those initial dips in light.

The data suggests the collision occurred at an orbit comparable to that of the Earth’s, and took more than a half a year to largely dissipate.

All of this is a reasonable hypothesis based on the data available. Though there is a lot of uncertainty in this conclusion, the researchers considered other explanations, such as variability in the star itself, and found them less credible.

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A nearby red dwarf star has a solar system of four planets, one in the habitable zone

9:11 am

According to a new analysis of new data, astronomers now think the nearby red dwarf star GJ 887, only about 11 light years away, not only has a solar system of four planets, one of those planets is is a super-Earth orbiting the star in the habitable zone.

From the abstract:

With the Bayesian analysis, we confirmed a four-planet model, including the two previously known planets at periods of 9.2619 ± 0.0005 d and 21.784 ± 0.004 d, as well as two newly confirmed exoplanets: an Earth-mass planet, with a 4.42490 ± 0.00014 d period and a sub-meter-per-second amplitude, and a super-Earth with a 50.77 ± 0.05 d period located in the habitable zone (HZ). This super-Earth is the second closest planet in the HZ, after Proxima Cen b.

The super-Earth has a mass estimated to be anywhere from two to ten times that of Earth, so if any life could exist on it that life would have to be adapted for an extremely strong gravitational field. The star itself appears to be relatively benign for an M dwarf, having a “low level of magnetic activity”, though it does exhibit some flaring that could pose a threat to the development of life on the planet.

Unfortunately, this system is not aligned in a way to allow transits of these planets across the face of the star, so these conclusions are based on gravitational wobbles of the star analyzed by computer modeling. Lots of uncertainty. The scientists hope that direct observations of the planet by future space telescopes will reduce these uncertainties. At the moment, the proposed privately-funded Lazuli optical orbiting telescope has the best chance of doing this work, but it isn’t expected to launch before the end of the decade. It will have a 3.1 meter primary mirror, larger than Hubble’s 2.4 meter mirror.

It is a so far very slow news day in space.

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SpaceX launches NASA’s Pandora exoplanet space telescope

9:32 am

SpaceX today successfully launched a new NASA space telescope, Pandora, its Falcon 9 rocket lifting off from Vandenberg in California.

Pandora is a smallsat focused on studying 20 stars known to have transiting exoplanets. It will look at each repeatedly to draw as much information about the star and the exoplanet as possible. Also deployed were two other NASA smaller astronomy cubesats.

The Falcon 9 first stage completed its 5th flight, landing back at Vandenberg. The two fairing halves completed their first and seventh flights respectively.

At this moment, SpaceX is the only entity to have launched in 2026. This was its fourth launch.

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New data from VLT uncovers numerous debris disks around stars

9:01 am

A sampling of debris disks
Click for original

Using a new instrument on the Very Large Telescope (VLT) in Chile, astronomers have compiled a catalog of 51 potential exoplanet solar systems, all with intriguing debris disks surround the stars with features suggesting the existence of asteroids and comets.

The image to the right shows a sampling of those systems. From the press release:

“To obtain this collection, we processed data from observations of 161 nearby young stars whose infrared emission strongly indicates the presence of a debris disk,” says Natalia Engler (ETH Zurich), the lead author of the study. “The resulting images show 51 debris disks with a variety of properties — some smaller, some larger, some seen from the side and some nearly face-on – and a considerable diversity of disk structures. Four of the disks had never been imaged before.”

Comparisons within a larger sample are crucial for discovering the systematics behind object properties. In this case, an analysis of the 51 debris disks and their stars confirmed several systematic trends: When a young star is more massive, its debris disk tends to have more mass as well. The same is true for debris disks where the majority of the material is located at a greater distance from the central star.

Arguably the most interesting feature of the SPHERE debris disks are the structures within the disks themselves. In many of the images, disks have a concentric ring- or band-like structure, with disk material predominantly found at specific distances from the central star. The distribution of small bodies in our own solar system has a similar structure, with small bodies concentrated in the asteroid belt (asteroids) and the Kuiper belt (comets).

The data from various telescopes both on the ground and in space is increasingly telling us that our solar system is not unique, and that the galaxy is filled with millions of similar systems, all in different states of formation. This hypothesis is further strengthened by the appearance of interstellar comet 3I/Atlas, which despite coming from outside our solar system is remarkably similar to the comets formed here.

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Webb: Accretion disk surrounding exoplanet rich in carbon molecules

10:14 am

Using the Webb Space Telescope, scientists have detected a host of carbon molecules inside an accretion disk that surrounds an exoplanet circling a baby star 625 light years away.

Infrared observations of CT Cha b were made with Webb’s MIRI (Mid-Infrared Instrument) using its medium resolution spectrograph. An initial look into Webb’s archival data revealed signs of molecules within the circumplanetary disk, which motivated a deeper dive into the data.

…Ultimately, the team discovered seven carbon-bearing molecules within the planet’s disk, including acetylene (C2H2) and benzene (C6H6). This carbon-rich chemistry is in stark contrast to the chemistry seen in the disk around the host star, where the researchers found water but no carbon. The difference between the two disks offers evidence for their rapid chemical evolution over only than 2 million years.

You can read the original paper here [pdf]. The exoplanet itself is thought to have a mass 14 to 24 times that of Jupiter, making it almost a brown dwarf star. The NASA makes a big deal claiming this disk is forming a moon around the exoplanet, but that is not what the paper finds. This research did not find any evidence of a new moon exoplanet.

Instead, the paper found an accretion disk rich in carbon molecules, a finding that is significant on its own. It also found that that the accretion disk around the central star, while lacking carbon molecules, appears rich in water.

In other words, this baby solar system is packed with the right material for eventually producing life. Moreover, in this system’s relatively short life, two million years, these materials were able to sort themselves out so that the star has one concentration of material while the exoplanet has another. Both facts suggest that organic chemistry is common in the universe, and can evolve fast.

That is the important discovery here.

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Webb: An Earth-sized exoplanet in habitable zone appears to lack an atmosphere

10:17 am

Scientists using the Webb Space Telescope have concluded that an Earth-sized exoplanet, orbiting the red dwarf star Trappist-1 in the habitable zone, does not appear to have an atmosphere, or if it does have one it is not like Earth’s.

The TRAPPIST-1 system is located 40 light-years away and was revealed as the record-holder for most Earth-sized rocky planets around a single star in 2017, thanks to data from NASA’s retired Spitzer Space Telescope and other observatories. Due to that star being a dim, relatively cold red dwarf, the “habitable zone” or “Goldilocks zone” – where the planet’s temperature may be just right, such that liquid surface water is possible – lies much closer to the star than in our solar system. TRAPPIST-1 d, the third planet from the red dwarf star, lies on the cusp of that temperate zone, yet its distance to its star is only 2 percent of Earth’s distance from the Sun. TRAPPIST-1 d completes an entire orbit around its star, its year, in only four Earth days.

Webb’s NIRSpec (Near-Infrared Spectrograph) instrument did not detect molecules from TRAPPIST-1 d that are common in Earth’s atmosphere, like water, methane, or carbon dioxide.

You can read the paper here [pdf].

The likelihood of life on this exoplanet has always been slim, simply because it orbits so close to the red dwarf, where it is vulnerable to the high energy flares the star periodically releases.

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Webb: Evidence of gas giant exoplanet orbiting the central star of Alpha Centuri

2:54 pm

Webb infrared data
Click for original image.

The uncertainty of science: Astronomers using the Webb Space Telescope now think they have detected a gas giant exoplanet orbiting the central star of the Alpha Centuri triple star system, the closest star to our Sun at only four light years distance.

The false-color image to the right shows the candidate exoplanet labeled as S1, with the light of the central star blocked out but indicated by the star at the center. A lot of processing was required to bring out this bright blob, including eliminating optical effects that normally act to hide such objects.

Alpha Centauri, located in the far southern sky, is made up of the binary Alpha Centauri A and Alpha Centauri B, both Sun-like stars, and the faint red dwarf star Proxima Centauri. Alpha Centauri A is the third brightest star in the night sky. While there are three confirmed planets orbiting Proxima Centauri, the presence of other worlds surrounding Alpha Centauri A and Alpha Centauri B has proved challenging to confirm.

Now, Webb’s observations from its Mid-Infrared Instrument (MIRI) are providing the strongest evidence to date of a gas giant orbiting Alpha Centauri A. …Based on the brightness of the planet in the mid-infrared observations and the orbit simulations, researchers say it could be a gas giant approximately the mass of Saturn orbiting Alpha Centauri A in an elliptical path varying between 1 to 2 times the distance between Sun and Earth.

If confirmed the exoplanet would be orbiting the star within the habitable zone, though as a gas giant life as we know it would likely be impossible. The location, only four light years away, makes this exoplanet and the entire system a prime target for further observations.

Hat tip to BtB’s stringer Jay.

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Scientists discover another exoplanet that theories say should not exist

10:20 am

The uncertainty of science: Scientists using telescopes both in orbit and on the ground have discovered a small red dwarf star with only 20% the mass of our Sun with a gas giant exoplanet with about half the mass of Saturn but a bit larger in size.

The problem is that the theory for the formation of such gas giants predicts that they should not form around small red dwarfs such as this star.

The most widely held theory of planet formation is called the core accretion theory. A planetary core forms first through accretion (gradual accumulation of material) and as the core becomes more massive, it eventually attracts gases that form an atmosphere. It then gets massive enough to enter a runaway gas accretion process to become a gas giant.

In this theory, the formation of gas giants is harder around low-mass stars because the amount of gas and dust in a protoplanetary disc around the star (the raw material of planet formation) is too limited to allow a massive enough core to form, and the runaway process to occur.

Yet the existence of TOI-6894b (a giant planet orbiting an extremely low-mass star) suggests this model cannot be completely accurate and alternative theories are needed.

You can read the paper here. The exoplanet orbits the star every 3.37 days, and each transit across the face of the star has been easily detected by numerous telescopes. Further spectroscopic observations using the Webb Space Telescope will be able to characterize the exoplanet’s atmosphere more fully.

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Astronomers detect evidence of numerous protoplanetary disks in three molecular clouds near the galactic center

11:58 am

Using the ground-based ALMA telescope in Chile, astronomers have detected evidence of the existence of numerous protoplanetary disks in three molecular clouds near the galactic center.

The findings suggest that over three hundred such systems may already be forming within just these three CMZ clouds [Central Molecular Zone]. “It is exciting that we are detecting possible candidates for protoplanetary disks in the Galactic Centre. The conditions there are very different from our neighbourhood, and this may give us a chance to study planet formation in this extreme environment,” said Professor Peter Schilke at the University of Cologne.

You can read the paper here.

These results once again suggest that the formation of stars, solar systems, and planets is more ubiquitous than ever expected, that they can all form in very extreme and hostile environments, of which the center of the Milky Way is one of the most hostile.

And if planets can form here, they can likely form everywhere else. This increases the likelihood of many planets throughout the galaxy capable of supporting the development of life.

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Transiting exoplanet appears to be losing matter with each transit

8:45 am

Astronomers using the TESS space telescope have discovered an exoplanet about 140 light years away that appears to have a tail of trailing material that is gaining mass with each transit as the planet slowly disintegrates.

The typical signal of an orbiting exoplanet looks like a brief dip in a light curve, which repeats regularly, indicating that a compact body such as a planet is briefly passing in front of, and temporarily blocking, the light from its host star.

This typical pattern was unlike what Hon and his colleagues detected from the host star BD+05 4868 A, located in the constellation of Pegasus. Though a transit appeared every 30.5 hours, the brightness took much longer to return to normal, suggesting a long trailing structure still blocking starlight. Even more intriguing, the depth of the dip changed with each orbit, suggesting that whatever was passing in front of the star wasn’t always the same shape or blocking the same amount of light.

You can read the peer-reviewed paper here [pdf]. Their calculations estimate the planet will disintegrate entirely in about two million years.

Because of the nature of these transits, the relative nearness of the star system, and the existence of this tail of material, this exoplanet is an excellent candidate for studying the planet’s structure and make-up. The scientists advocate further studies using a range of telescopes, including Webb and Hubble.

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Astronomers detect chemicals on exoplanet that on Earth come from life

9:11 am

The uncertainty of science: Using the Webb Space Telescope, astronomers have detected two different molecules that on Earth are only linked with biology in the atmosphere of an exoplanet orbiting a red dwarf star within its habitable zone.

Earlier observations of K2-18b — which is 8.6 times as massive and 2.6 times as large as Earth, and lies 124 light years away in the constellation of Leo — identified methane and carbon dioxide in its atmosphere. This was the first time that carbon-based molecules were discovered in the atmosphere of an exoplanet in the habitable zone. Those results were consistent with predictions for a ‘Hycean’ planet: a habitable ocean-covered world underneath a hydrogen-rich atmosphere.

However, another, weaker signal hinted at the possibility of something else happening on K2-18b. “We didn’t know for sure whether the signal we saw last time was due to DMS, but just the hint of it was exciting enough for us to have another look with JWST using a different instrument,” said Professor Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research.

…The earlier, tentative, inference of DMS was made using JWST’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph) instruments, which together cover the near-infrared (0.8-5 micron) range of wavelengths. The new, independent observation [of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS] used JWST’s MIRI (Mid-Infrared Instrument) in the mid-infrared (6-12 micron) range.

This data is not yet proof of biology. For example, the concentrations of these molecules in K2-18b’s atmosphere is thousands of times greater than on Earth. It is just as likely that numerous as yet unknown non-biological chemical processes in this alien environment have produced these chemicals. The scientists however are encouraged because the theories about ocean life on this kind of habitable ocean-covered superearth had predicted this high concentration of these chemicals.

At the same time, they readily admit there are many uncertainties in their data. They have asked for another 16 to 24 hours of observation time on Webb — a very large chunk rarely given out to one research group — to reduce these uncertainties.

You can read the peer-reviewed paper here [pdf].

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Survey of protoplanetary disks finds their size varies significantly

9:02 am

Proto-planetary disks of all sizes
Click for original image.

A survey of the protoplanetary disks in a star-forming region about 400 light years from Earth has found that the size of the disks can vary considerably, with many much smaller than our own solar system.

Using ALMA [Atacama Large Millimeter/submillimeter Array in Chile], the researchers imaged all known protoplanetary discs around young stars in Lupus, a star forming region located about 400 light years from Earth in the southern constellation Lupus. The survey reveals that two-thirds of the 73 discs are small, with an average radius of six astronomical units, this is about the orbit of Jupiter. The smallest disc found was only 0.6 astronomical units in radius, smaller than the orbit of Earth.

…The small discs were primarily found around low-mass stars, with a mass between 10 and 50 percent of the mass of our Sun. This is the most common type of star found in the universe.

You can read the research paper here [pdf]. The image to the right, figure 1 from the paper, shows 71 of those disks, with two-thirds clearly much smaller than our solar system.

Because exoplanet surveys have found many small exoplanets around low-mass stars, this new data suggests that planets can also form from these small accretion disks, and that planet formation is also ubiquitous throughout the universe.

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Astronomers have discovered four sub-Earth-sized exoplanets orbiting Barnard’s Star

10:44 am

Based on data from several ground-based telescopes, astronomers now believe that Barnard’s Star, the nearest single star to our Sun at a distance of about six light years away, has a solar system of at least four sub-Earth-sized planets.

After rigorously calibrating and analyzing data taken during 112 nights over a period of three years, the team found solid evidence for three exoplanets around Barnard’s Star, two of which were previously classified as candidates. The team also combined data from MAROON-X with data from a 2024 study done with the ESPRESSO instrument at the European Southern Observatory’s Very Large Telescope in Chile to confirm the existence of a fourth planet, elevating it as well from candidate to bona fide exoplanet.

You can read the paper here. The scientists estimate the minimum masses of these exoplanets to range from 19% to 34% that of the Earth, with their maximum mass not exceeding 57% of the Earth. All are believed to be rocky planets orbiting just inside the star’s habitable zone.

Astronomers have been trying to detect exoplanets around Barnard’s Star for more a century. Several previous “discoveries” were later retracted. This result however appears somewhat firm though of course there are a lot of uncertainties in the result.

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Scientists: X-rays from the Helix Nebula caused by the destruction of a planet

10:12 am

A composite image of the Helix Nebula
A composite image of the Helix Nebula, combining data
from multiple ground- and space-based telescopes.
Click for original image.

Using data collected by multiple ground-bases and space telescopes over decades, scientists now think the previously unexplained high energy X-rays coming from the white dwarf star at the center of the Helix Nebula are caused by the destruction of a Jupiter-sized exoplanet.

The besieged planet could have initially been a considerable distance from the white dwarf but then migrated inwards by interacting with the gravity of other planets in the system. Once it approached close enough to the white dwarf, the gravity of the star would have partially or completely torn the planet apart. “The mysterious signal we’ve been seeing could be caused by the debris from the shattered planet falling onto the white dwarf’s surface, and being heated to glow in X-rays,” said co-author Martin Guerrero of The Institute of Astrophysics of Andalusia in Spain. “If confirmed, this would be the first case of a planet seen to be destroyed by the central star in a planetary nebula.”

The study shows that the X-ray signal from the white dwarf has remained approximately constant in brightness between 1992, 1999, and 2002 (with observations by ROSAT, Chandra and XMM respectively). The data, however, suggests there may be a subtle, regular change in the X-ray signal every 2.9 hours, providing evidence for the remains of a planet exceptionally close to the white dwarf.

You can read the original paper here. The Helix Nebula is about 650 light years away, and is one of the most studied planetary nebula, believed to have formed when the central star collapsed into a white dwarf.

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Webb finds six exoplanets, all flying in interstellar space without a star

11:11 am

Astronomers using the Webb Space Telescope have discovered six different planets ranging in mass 5 to 10 times that of Jupiter, all unattached to any star or solar system.

The most intriguing of the starless objects is also the lightest, having an estimated mass of five Jupiters (about 1,600 Earths). The presence of a dusty disk means the object almost certainly formed like a star, as space dust generally spins around a central object in the early stages of star formation, said Langeveld, a postdoctoral researcher in Jayawardhana’s group.

All of these starless planets likely formed like this one, coalescing like a star does but unlike a star never having enough mass to ignite.

The astronomers are next going to attempt to detect the atmosphere’s of these rogue exoplanets, though it is not clear exactly how they will do this unless one of the exoplanets just happened to transit across a more distant star, something that simply does not happen very often.

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