Tag: exoplanets

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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Webb takes infrared image of exoplanet

10:02 am

A Jupiter-sized exoplanet imaged by Webb
Click for original image.

Cool image time! Using the Webb Space Telescope, scientists have taken an infrared false color image of a multi-Jupiter-sized exoplanet located only twelve light years away and orbiting the K-type star Epsilon Indi A.

That picture, cropped, reduced, and sharpened to post here, is to the right. The light of the star, indicated by the star symbol, has been blocked by Webb’s coronagraph, the size of which is shown by the dashed circle. The exoplanet is the orange blob to the left.

[This exoplanet] is one of the coldest exoplanets to be directly detected, with an estimated temperature of 35 degrees Fahrenheit (2 degrees Celsius) — colder than any other imaged planet beyond our solar system, and colder than all but one free-floating brown dwarf. The planet is only around 180 degrees Fahrenheit (100 degrees Celsius) warmer than gas giants in our solar system. This provides a rare opportunity for astronomers to study the atmospheric composition of true solar system analogs.

The data also revealed that the exoplanet is twice as massive as expected and has a slightly different orbit than expected based on previous less precise data.

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Astronomers discover an exoplanet with the most eccentric orbit so far found

9:41 am

Using the TESS space telescope, astronomers have discovered a gas giant exoplanet with the most eccentric orbit so far found, circling a star about 1,100 light years away.

On Jan. 12, 2020, TESS picked up a possible transit of the star TIC 241249530. Gupta and his colleagues at Penn State determined that the transit was consistent with a Jupiter-sized planet crossing in front of the star. They then acquired measurements from other observatories of the star’s radial velocity, which estimates a star’s wobble, or the degree to which it moves back and forth, in response to other nearby objects that might gravitationally tug on the star. Those measurements confirmed that a Jupiter-sized planet was orbiting the star and that its orbit was highly eccentric, bringing the planet extremely close to the star before flinging it far out.

Prior to this detection, astronomers had known of only one other planet, HD 80606 b, that was thought to be an early hot Jupiter. That planet, discovered in 2001, held the record for having the highest eccentricity, until now.

The exoplanet’s orbit is presently 167 days long, at its closest stellar approach dipping 10 times closer to its star than Mercury is from the Sun, and at its farthest point zipping just beyond Earth’s distance.

Computer simulations suggest that in a billion years this orbit will decay into a more circular orbit close to the star, turning this gas giant into a hot Jupiter roasted by its star continually.

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Webb infrared spectroscopy detects differences between morning and evening on tidally-locked exoplanet

9:36 am

Webb spectroscopic data
Click for original image.

Astronomers using Webb Space Telescope’s infrared spectroscopy have now detected distinct differences in the morning and evening atmosphere of a tidally-locked gas giant exoplanet.

The graph, cropped, reduced, sharpened, annotated to post here, shows the differences. From the caption:

Researchers using NASA’s James Webb Space Telescope have finally confirmed what models have previously predicted: An exoplanet has differences between its eternal morning and eternal evening atmosphere. WASP-39 b, a giant planet with a diameter 1.3 times greater than Jupiter, but similar mass to Saturn that orbits a star about 700 light-years away from Earth, is tidally locked to its parent star. This means it has a constant dayside and a constant nightside—one side of the planet is always exposed to its star, while the other is always shrouded in darkness.

Using Webb’s NIRSpec (Near-Infrared Spectrograph), astronomers confirmed a temperature difference between the eternal morning and eternal evening on WASP-39 b, with the evening appearing hotter by roughly 300 Fahrenheit degrees (about 200 Celsius degrees). They also found evidence for different cloud cover, with the forever morning portion of the planet being likely cloudier than the evening.

The actual temperatures of each terminator are quite hot, approximately 1,150 and 1450 degrees Fahrenheit respectively. Computer modeling suggests “the prevailing winds are likely moving from the night side across the morning terminator, around the dayside, across the evening terminator and then around the nightside,” with wind speeds thousands of miles per hour.

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Webb: An exoplanet in the habitable zone with a possible nitrogen/CO2 atmosphere and water ocean

8:51 am

Using the Webb Space Telescope, astronomers have obtained new transiting spectroscopy of a “mini-Neptune-sized” exoplanet that circles in the habitable zone a red dwarf star about 48 light years away and have concluded that it appears to have a nitrogen/carbon dioxide atmosphere and even a water ocean.

While it is still only a tentative result, the presence of a nitrogen-rich atmosphere on LHS 1140 b would suggest the planet has retained a substantial atmosphere, creating conditions that might support liquid water. This discovery favors the water-world/snowball scenario as the most plausible.

Current models indicate that if LHS 1140 b has an Earth-like atmosphere, it would be a snowball planet with a vast “bull’s-eye” ocean measuring about 4,000 kilometers in diameter, equivalent to half the surface area of the Atlantic Ocean. The surface temperature at the centre of this alien ocean could even be a comfortable 20 degrees Celsius [68 degrees Fahrenheit]. [emphasis mine]

You can read the preprint of the paper here [pdf].

The highlighted phrase must be noted. These results contain a lot of uncertainties and assumptions. However, the data is tantalizing, to say the least, and justify more observations using Webb. The scientists argue in their paper that because there are only about eight transits of the exoplanet per year — requiring several years of observations to pin down this data more precisely — and because Webb has a limited life expectancy as an infrared observatory, this star should get observational priority.

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Webb: Hot Jupiter exoplanet has atmosphere with the smell of rotten eggs

9:20 am

Using spectroscopy from the infrared Webb Space Telescope, astronomers have measured some of the molecules in exoplanet HD 189733 b, one of the first hot Jupiter exoplanets ever discovered, and found it has an atmosphere rich in hydrogen sulfide, which emits a smell like rotten eggs.

In addition to detecting hydrogen sulfide, the team analyzed the planet’s oxygen and carbon content, pinpointing water, carbon dioxide and carbon monoxide as major components of the planetary atmosphere. Measuring these heavy elements allows astronomers to compare the composition of exoplanets to that of gas giants in our solar system like Jupiter and Uranus.

The exoplanet, about 64 light years away, has an orbit lasting only about two Earth days, with atmospheric temperatures has hot as 1,700 degrees Fahrenheit.

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The “Vulcan” exoplanet discovered in 2018 now refuted

9:52 am

In 2018 astronomers had thought they had detected an exoplanet orbiting the star 40 Eridani A — which is where in Star Trek the home world Mr. Spock was supposed to be located.

That discovery has now been refuted by much more precise observations.

[T]he planet signal is really the flickering of something on the star’s surface that coincides with a 42-day rotation – perhaps the roiling of hotter and cooler layers beneath the star’s surface, called convection, combined with stellar surface features such as spots and “plages,” which are bright, active regions.

In other words, this exoplanet does not exist. For once at least life did not imitate art.

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A planet with the density of cotton candy?

10:32 am

The uncertainty of science: According to data obtained from ground-based telescopes of a newly discovered transiting exoplanet, that planet has the density of cotton candy.

This new planet, located 1,200 light-years from Earth, is 50% larger than Jupiter but seven times less massive, giving it an extremely low density comparable to that of cotton candy. “WASP-193b is the second least dense planet discovered to date, after Kepler-51d, which is much smaller,” explains Khalid Barkaoui, a Postdcotral Researcher at ULiège’s EXOTIC Laboratory and first author of the article published in Nature Astronomy. Its extremely low density makes it a real anomaly among the more than five thousand exoplanets discovered to date. This extremely-low-density cannot be reproduced by standard models of irradiated gas giants, even under the unrealistic assumption of a coreless structure.”

Such a gas giant is not impossible. For example, Saturn’s density is so low that if you could find an ocean large enough it would float. The scientists theorize that this exoplanet is likly comprised mostly of hydrogen and helium.

Nonetheless, there are phenomenon here that we certainly do not understand.

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TESS resumes science operations

9:26 am

Engineers have corrected the issue that put the space telescope TESS into safe mode on April 8, 2024 and have resumed science operations.

The operations team determined this latest safe mode was triggered by a failure to properly unload momentum from the spacecraft’s reaction wheels, a routine activity needed to keep the satellite properly oriented when making observations. The propulsion system, which enables this momentum transfer, had not been successfully repressurized following a prior safe mode event April 8. The team has corrected this, allowing the mission to return to normal science operations. The cause of the April 8 safe mode event remains under investigation.

As for that April 8th safe mode, though engineers were able to return the spacecraft to normal operations after about a week, that they still do not know what caused it remains a concern.

TESS takes high resolution survey images of 93% of the sky about once per month. By comparing the data from each scan, scientists have discovered so far more than 300 transiting exoplanets as well as many supernovae and other phenomenon related to variable stars.

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A molecule found by Rosetta on Comet 67P/C-G proves discovering life on exoplanets will not be easy

12:50 pm

The uncertainty of science: Scientists have long assumed that the molecule dimethyl sulfide (DMS) is an excellent biosignature of life, since it is only produced by life here on Earth. When they discovered it in the atmosphere of an exoplanet last year many thought, especially in the media, that it proved that life existed on that exoplanet.

A scientist who had worked on the Rosetta mission to the Comet 67P/C-G thought otherwise, that DMS was not a reliable biosignature and quickly proved it.

Just 1 day of data from Rosetta’s mass spectrometer, an instrument that can identify molecules by their specific weights, was enough for [Nora Hänni] and her colleagues to find DMS. She says lab experiments will now be needed to pin down exactly how DMS forms in space, where ultraviolet light and cosmic rays can power the synthesis of complex organic molecules. Another important question is whether comets could deliver significant amounts of DMS to a planet—and perhaps account for detections like the K2-18b claim. “If it impacted the atmosphere, it could contaminate the atmosphere of the planet,” Noack says, potentially complicating searches for alien life.

Like the fake news in 2020 that life was found in the atmosphere of Venus (it wasn’t), it is a big mistake to use the detection of one molecule to assume it is evidence of life on an alien world. The universe is far more complicated.

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Another exoplanet found in habitable zone

9:55 am

Astronomers using both space- and ground-based telescopes have confirmed the existence of another rocky exoplanet inside the habitable zone of its star.

The star is a red dwarf 137 light years away. The exoplanet, dubbed TOI-175 b, is estimated to be larger than Earth, with a diameter 1.5 times that of our home planet. It orbits its star every nineteen days. Even more intriguing, the data suggests this star has a second exoplanet even better positioned in the habitable zone that would be the smallest habitable-zone exoplanet so far found, about the size of Earth.

The second planet however is not yet confirmed.

This discovery is no longer very unique. In the past few years astronomers have discovered a plethora of Earth-sized exoplanets, many in the habitable zone.

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Astronomers discover Earth-sized exoplanet roasted by a Sunlike star

10:18 am

Using data from the TESS space telescope, astronomers have discovered an Earth-sized exoplanet in a 4.2 day orbit around a G-type star like our Sun about 70 light years away.

The tidally locked planet is very close to Earth size (it is approximately 1.1 times the diameter of our own planet) and it’s orbiting a star that’s similar to the size of our Sun (the star is about 0.91 the size and 0.99 the mass of the Sun).

The star in this system is a G-type star, the same type as our Sun. But HD 63433 d orbits much closer to its star than we do, with a minuscule 4.2 day long “year” and extremely high temperatures on its dayside.

To read the research paper, go here. At an estimated age of only 400 million years, this exoplanet and its solar system of at least two other planets is much younger than the 4.5-billion-year-old Earth. Though the press release and paper note the possibility that it is similar in many ways to Io, a volcanic planet covered with lava, we don’t know this. All we know is that it is roasted by its star by orbiting so close to it.

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Astronomers: A solar system with six Earth-sized planets orbiting in perfect resonance

9:38 am

The resonances of this exo-solar system
Click for original image.

Astronomers today announced the discovery of a solar system with six Earth-sized exoplanets that orbit their Sun-like star in a synchronized manner, their orbits in a gravitational lock-step called resonance.

The graphic to the right illustrates that pattern. From the press release:

While multi-planet systems are common in our galaxy, those in a tight gravitational formation known as “resonance” are observed by astronomers far less often. In this case, the planet closest to the star makes three orbits for every two of the next planet out – called a 3/2 resonance – a pattern that is repeated among the four closest planets.

Among the outermost planets, a pattern of four orbits for every three of the next planet out (a 4/3 resonance) is repeated twice. And these resonant orbits are rock-solid: The planets likely have been performing this same rhythmic dance since the system formed billions of years ago. Such reliable stability means this system has not suffered the shocks and shakeups scientists might typically expect in the early days of planet formation – smash-ups and collisions, mergers and breakups as planets jockey for position. And that, in turn, could say something important about how this system formed. Its rigid stability was locked in early; the planets’ 3/2 and 4/3 resonances are almost exactly as they were at the time of formation. More precise measurements of these planets’ masses and orbits will be needed to further sharpen the picture of how the system formed.

All the planets have orbits less than 55 days long, and though all have masses less than six Earth-masses, data suggests they more resemble Neptune because of their expanded gaseous make-up caused by the close orbits to the star.

Future observations are planned, most especially with Webb because its infrared capability will detect much of the chemistry of this system.

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Astronomers detect nano-sized quartz crystals in atmosphere of exoplanet

9:33 am

Using both the Hubble and Webb space telescopes in space, astronomers have detected nano-sized quartz crystals in the atmosphere of a Jupiter-class exoplanet orbiting its star every 3.7 days.

Silicates (minerals rich in silicon and oxygen) make up the bulk of Earth and the Moon as well as other rocky objects in our solar system, and are extremely common across the galaxy. But the silicate grains previously detected in the atmospheres of exoplanets and brown dwarfs appear to be made of magnesium-rich silicates like olivine and pyroxene, not quartz alone – which is pure SiO2.

The result from this team, which also includes researchers from NASA’s Ames Research Center and NASA’s Goddard Space Flight Center, puts a new spin on our understanding of how exoplanet clouds form and evolve. “We fully expected to see magnesium silicates,” said co-author Hannah Wakeford, also from the University of Bristol. “But what we’re seeing instead are likely the building blocks of those, the tiny ‘seed’ particles needed to form the larger silicate grains we detect in cooler exoplanets and brown dwarfs.”

These tiny quartz crystals are condensing out in the clouds themselves, due to the high temperatures and pressures there. The exoplanet itself is unusual because though its mass is one half that of Jupiter, its volume is seven times larger. This gives it a very large and deep atmosphere, thus providing the environment for crystal formation.

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The possibility of more than one exoplanet sharing the same orbit

9:27 am

PDS 70, as seen by ALMA
The Trojan debris clouds around PDS 70, as seen by ALMA

The uncertainty of science: Astronomers have detected evidence that suggests the possibility of more than one exoplanet sharing the same orbit around PDS 70, a star 400 light years away.

This young star is known to host two giant, Jupiter-like planets, PDS 70b and PDS 70c. By analysing archival ALMA observations of this system, the team spotted a cloud of debris at the location in PDS 70b’s orbit where Trojans are expected to exist.

Trojans occupy the so-called Lagrangian zones, two extended regions in a planet’s orbit where the combined gravitational pull of the star and the planet can trap material. Studying these two regions of PDS 70b’s orbit, astronomers detected a faint signal from one of them, indicating that a cloud of debris with a mass up to roughly two times that of our Moon might reside there.

The press release — as well as most news reports — touts the possibility that they have found a second planet in this orbit. They have not, and are likely not going to. As noted above, the data indicates the presence of “a cloud of debris”, which is most likely a clustering of Trojan asteroids, just as the more than 12,000 asteroids we see in the two Trojan points in Jupiter’s orbit.

Nonetheless, this is the first detection of what appears to be a Trojan clustering in the accretion disk of a young star.

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Astronomers detect vaporized elements in atmosphere of hot Jupiter-sized exoplanet

8:23 am

Using the Gemini telescope in Hawaii, astronomers have detected several elements in atmosphere of hot Jupiter-sized exoplanet, dubbed WASP-76b, that would normally be found in rocks, but here are vaporized because the exoplanet orbits so close to its star.

In 2020 and 2021, using Gemini North’s MAROON-X (a new instrument specially designed to detect and study exoplanets), Pelletier and his team observed the planet as it passed in front of its host star on three separate occasions. These new observations uncovered a number of rock-forming elements in the atmosphere of WASP-76b, including sodium, potassium, lithium, nickel, manganese, chromium, magnesium, vanadium, barium, calcium, and, as previously detected, iron.

Due to the extreme temperatures of WASP-76b’s atmosphere, the elements detected by the researchers, which would normally form rocks here on Earth, are instead vaporized and thus present in the atmosphere in their gaseous forms. While these elements contribute to the composition of gas giants in our Solar System, those planets are too cold for the elements to vaporize into the atmosphere making them virtually undetectable.

The data not only suggests such elements exist in the solar system’s gas giants, but that such elements are common in solar systems elsewhere. That possibility increases the chances of other planets like Earth, capable of sustaining life as we know it, in addition to sustaining life as we don’t know it.

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Webb finds Earth-sized exoplanet likely too hot to have atmosphere

9:25 am

The uncertainty of science: Using the infrared Webb Space Telescope, scientists have measured the temperature of the Earth-sized exoplanet, dubbed Trappist-1b, and found its temperature is probably too hot to have atmosphere.

The red dwarf star Trappist-1is about 40 light years from Earth, and in 2017 was found to have a solar system of seven exoplanets, all rocky terrestrial planets like the inner planets of our solar system. Trappist-1b is the innermost exoplanet. To measure its temperature, Webb observed the star while the planet was eclipsed by the star as well as when it was not, and measured the tiny difference in infrared light.

The team analyzed data from five separate secondary eclipse observations. “We compared the results to computer models showing what the temperature should be in different scenarios,” explained Ducrot. “The results are almost perfectly consistent with a blackbody made of bare rock and no atmosphere to circulate the heat. We also didn’t see any signs of light being absorbed by carbon dioxide, which would be apparent in these measurements.”

As this was the innermost of the star’s solar system, it is also the one most likely to lack an atmosphere. Webb’s observations of the system continue, so there is a chance that data about the other exoplanets will eventually tell us more about them.

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Webb detects “hot sand clouds” in atmosphere of exoplanet

10:40 am

Using the Webb Space Telescope, astronomers have detected “hot sand clouds” in atmosphere of exoplanet 40 light years away, along with evidence of water, methane, carbon monoxide, carbon dioxide, sodium, and potassium.

You can read the paper here [pdf]. The exoplanet itself appears to have some features that resemble that of a brown dwarf, or failed star, instead of an exoplanet.

Although VHS 1256 b is more on the heavier side of the known exoplanets, its gravity is relatively low compared to more massive brown dwarfs. Such very low-mass stars can only burn deuterium for a relatively short duration. Consequently, the planet’s silicate clouds can appear and remain higher in its atmosphere, where the JWST can detect them. Another reason its skies are so turbulent is the planet’s age. In astronomical terms, it is pretty young. Only 150 million years have passed since it formed. The planet’s heat stems from the recent formation process – and it will continue to change and cool over billions of years.

The sand clouds are hot, in the range of 1,500 degrees Fahrenheit.

These results were obtained as part of an early-release program from Webb, and illustrate the potential of the infrared space telescope for learning many specific details about brown dwarfs and exoplanets.

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VLT takes picture of exoplanet

9:20 am

VLT's picture of exoplanet
Click for original image.

The ground-based Very Large Telescope (VLT) in Chile has successfully taken a picture of an exoplanet four to six times larger than Jupiter that is circling its star at about the same distance as Saturn.

That picture, cropped to post here, is to the right. Other data from other observatories had suggested the star AF Leporis, 87.5 light years away, might have an exoplanet, so astronomers decided to focus VLT on it to see if it could spot it.

AF Leporis is about as massive and as hot as the sun, ESO wrote in the statement, and in addition to its one known planet the star also has a disk of debris similar to the solar system’s Kuiper Belt. AF Leporis is, however, much younger than the sun. At 24 million years old, it is about 200 times younger than our star. This young age makes AF Leporis and its planetary system especially intriguing for astronomers as it can provide important insights into the evolution of our own solar system.

To snap this picture, the VLT had to use adaptive optics to smooth out the fuzziness produced by the Earth’s atmosphere, while also blocking out the star’s own light (as shown by the black disk in the image).

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TESS finds a second Earthsize planet orbiting in the habitable zone of a star

9:37 am

TESS solar system

The orbiting survey telescope TESS has discovered a second Earthsize planet in a solar system of four exoplanets.

The graphic to the right, a screen capture from a short video provided by the press release, shows these four exoplanets. Planet D had previously been discovered. Planet E is the new discovery, and is thought to be 95% Earth’s mass and likely terrestrial in make-up. Both are near the inner edge of the habitable zone.

TOI 700 is a small, cool M dwarf star located around 100 light-years away in the southern constellation Dorado. In 2020, Gilbert and others announced the discovery of the Earth-size, habitable-zone planet d, which is on a 37-day orbit, along with two other worlds.

The innermost planet, TOI 700 b, is about 90% Earth’s size and orbits the star every 10 days. TOI 700 c is over 2.5 times bigger than Earth and completes an orbit every 16 days. The planets are probably tidally locked, which means they spin only once per orbit such that one side always faces the star, just as one side of the Moon is always turned toward Earth.

This discovery only underlines the infinite possibilities and variables that exist for life on other worlds. These planets might be similar in mass to the Earth and get about the same heat/light energy from their sun, but the star is very different, their orbits are very different, and their environment is very different.

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Astronomers determine that two super-Earths are not as rocky as previously believed

10:32 am

Using observations from both the Hubble Space Telescope and the now retired Spitzer infrared space telescope, astronomers now think that two super-Earth-sized explanets are not as rocky as previously believed, and are in fact liquid worlds with as much as half their make-up comprised of water. From the press release:

Water wasn’t directly detected at Kepler-138 c and d, but by comparing the sizes and masses of the planets to models, astronomers conclude that a significant fraction of their volume – up to half of it – should be made of materials that are lighter than rock but heavier than hydrogen or helium (which constitute the bulk of gas giant planets like Jupiter). The most common of these candidate materials is water.

“We previously thought that planets that were a bit larger than Earth were big balls of metal and rock, like scaled-up versions of Earth, and that’s why we called them super-Earths,” explained Björn Benneke, study co-author and professor of astrophysics at the University of Montreal. “However, we have now shown that these two planets, Kepler-138 c and d, are quite different in nature and that a big fraction of their entire volume is likely composed of water. It is the best evidence yet for water worlds, a type of planet that was theorized by astronomers to exist for a long time.”

With volumes more than three times that of Earth and masses twice as big, planets c and d have much lower densities than Earth. This is surprising because most of the planets just slightly bigger than Earth that have been studied in detail so far all seemed to be rocky worlds like ours. The closest comparison, say researchers, would be some of the icy moons in the outer solar system that are also largely composed of water surrounding a rocky core.

This data simply underlines a basic point: The information we have of all exoplanets is sparse, practically nil. Any conclusions about their make-up is an educated guess, at best. Even now the conclusion that these are water worlds should be treated with great skepticism.

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