Exoplanets – worlds of other suns

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Two massive Jupiter-sized exoplanets discovered with TESS

https://phys.org/news/2022-07-massive-j ... -tess.html
by Tomasz Nowakowski , Phys.org

Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has detected two new extrasolar planets. The newfound alien worlds, designated TOI-5152 b and TOI-5153 b, are the size of Jupiter but about three times more massive than the solar system's biggest planet. The finding is reported July 8 on the arXiv pre-print repository.

TESS is conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets. It has identified over 5,700 candidate exoplanets (TESS Objects of Interest, or TOI), of which 227 have been confirmed so far.

A group of astronomers led by Solène Ulmer-Moll of Geneva Observatory in Switzerland has recently confirmed another two TOI planets monitored by TESS. They report that transit signals have been identified in the light curves of two stars known as TOI-5152 and TOI-5153. The planetary nature of these signals was confirmed by follow-up observations.

"The discovery photometry was collected with the space-based mission TESS and follow-up observations were carried out from the ground with the photometric facility NGTS, and the high-resolution spectrographs CORALIE, FEROS, CHIRON, HARPS, and TRES," the researchers wrote in the paper.

TOI-5152 b has a radius of about 1.07 Jupiter radii and is approximately three times more massive than Jupiter. It orbits its parent star every 54.19 days, at a distance of some 0.31 AU from it. The planet's equilibrium temperature was measured to be 688 K. The host TOI-5152 is a G1-type star nearly two times larger than the sun, located about 1,200 light years away from the Earth. Its age is estimated to be between 1.4 and 6.8 billion years.

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A New Method to Detect Exoplanets
July 20, 2022

Introduction:

(EurekAlert) In recent years, a large number of exoplanets have been found around single ‘normal’ stars. New research shows that there may be exceptions to this trend. Researchers from The Autonomous University of Nuevo León (UANL), The National Autonomous University of Mexico (UNAM), and New York University Abu Dhabi suggest a new way of detecting dim bodies, including planets, orbiting exotic binary stars known as Cataclysmic Variables (CVs).

CVs are binary star systems in which the two stars are in extremely close proximity to each other; so close that the less massive object transfers mass to the more massive. CVs are typically formed of a small, cool type of star known as a red dwarf star, and a hot, dense star – a white dwarf. Red dwarf stars have a mass between 0.07 and 0.30 solar masses and a radius of around 20% of the Sun’s, while white dwarf stars have a typical mass of around 0.75 Solar masses and a very small radius similar to that of planet Earth.

In the CV system, the transfer of matter from the small star forms an accretion disk around the compact, more massive star. The brightness of a CV system mainly comes from this disk, and overpowers the light coming from the two stars. A third dim body orbiting a CV can influence the mass transfer rate between the two stars, and hence the brightness of the entire system. The method described in the new work is based on the change of brightness in the accretion disk due to perturbations of the third body that orbits around the inner two stars.

In their research, team leader Dr Carlos Chavez and his collaborators have estimated the mass and distance of a third body orbiting four different CVs using the changes in the brightness of each system. According to calculations carried out by the team, such brightness variations have very long periods in comparison to the orbital periods in the triple system. Two out of the four CVs appear to have bodies resembling planets in orbit around them.

Read more here: https://www.eurekalert.org/news-releases/959332

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Alien Friendly? Planet Poses Habitability Puzzle
by Kiona Smith
August 2, 2022

Introduction:

(Inverse) ASTRONOMERS have discovered a rocky exoplanet that’s only (potentially) friendly to life as we know it part of the time.

The planet, Ross 508 b, dips in and out of its star’s habitable zone (the region around a star where temperatures are just right for liquid water to exist on a planet’s surface) every few days, otherwise swinging too close to its star for comfort.

The National Astronomical Observatory of Japan-led team published its findings in the journal Publication of the Astronomical Society of Japan. https://academic.oup.com/pasj/advance- ... 4/6623879

WHAT’S NEW – Ross 508 b is a rocky world about four times more massive than Earth, and it zips around the red dwarf star Ross 508 once every 11 days. This makes for a breathtakingly short year, but it’s not as close as some other exoplanets’ daredevil orbits.

Because red dwarf stars like Ross 508 are drastically smaller and cooler than our Sun, their habitable zones tend to huddle much closer to the star’s warmth. So even in its close orbit about 5 million miles from its home star, Ross 508 b is just skimming the inner edge of the system’s habitable zone. (Mercury, for comparison, is about 37 million miles from the Sun.)

Read more here: https://www.inverse.com/science/is-ros ... habitable

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HD 23472: A multi-planetary system with three super-Earths and two potential super-Mercuries
S. C. C. Barros, O. D. S. Demangeon, Y. Alibert, V. Adibekyan, C. Lovis, et al.
A&A, Forthcoming article
Received: 17 June 2022 / Accepted: 26 July 2022

https://www.aanda.org/articles/aa/pdf/f ... 293-22.pdf

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A super-earth at the very nearby GJ 514 A super-earth at the very nearby GJ 514 Empty13th April 2022, 8:44 pm
A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone
https://arxiv.org/abs/2204.06376

We investigated the presence of planetary companions around the nearby (7.6 pc) and bright (V=9 mag) early-type M dwarf Gl 514, analysing 540 radial velocities collected over nearly 25 years with the HIRES, HARPS, and CARMENES spectrographs. The data are affected by time-correlated signals at the level of 2-3 ms−1 due to stellar activity, that we filtered out testing three different models based on Gaussian process regression. As a sanity cross-check, we repeated the analyses using HARPS radial velocities extracted with three different algorithms. We used HIRES radial velocities and Hipparcos-Gaia astrometry to put constraints on the presence of long-period companions, and we analysed TESS photometric data. We found strong evidence that Gl 514 hosts a super-Earth on a likely eccentric orbit, residing in the conservative habitable zone for nearly 34% of its orbital period. The planet Gl 514 b has minimum mass mbsinib=5.2±0.9 MEarth, orbital period Pb=140.43±0.41 days, and eccentricity eb=0.45+0.15−0.14. No evidence for transits is found in the TESS light curve. There is no evidence for a longer period companion in the radial velocities and, based on astrometry, we can rule out a ∼0.2 MJup planet at a distance of ∼3−10 au, and massive giant planets/brown dwarfs out to several tens of au. We discuss the possible presence of a second low-mass companion at a shorter distance from the host than Gl 514 b. Gl 514 b represents an interesting science case to study the habitability of planets on eccentric orbits. We advocate for additional spectroscopic follow-up to get more accurate and precise planetary parameters. Further follow-up is also needed to investigate sub \ms and shorter period signals.

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New rare 'hot sub-Neptune' exoplanet discovered
https://phys.org/news/2022-08-rare-hot- ... lanet.html
by Tomasz Nowakowski , Phys.org

Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has detected a new alien world. The newfound exoplanet, designated TOI-2196 b, turns out to be a type of a rare "hot sub-Neptune." The discovery was detailed in a paper published August 11 on arXiv.org.

TESS is conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets. It has identified over 5,800 candidate exoplanets (TESS Objects of Interest, or TOI), of which 233 have been confirmed so far.

Now, a group of astronomers led by Carina M. Persson of the Chalmers University of Technology in Sweden, has recently confirmed another TOI monitored by TESS. They report that a transit signal has been identified in the light curve of a G-type star known as TOI-2196. The planetary nature of this signal was confirmed by follow-up radial velocity (RV) measurements with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph on the ESO 3.6 m telescope in Chile.

"We present the detection and the analysis of the hot and volatile rich planet TOI-2196 b. It is smaller than Neptune but 50% more massive, resulting in a high bulk density for this type of planet," the researchers wrote in the paper.

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A Reanalysis of the Composition of K2-106b: an Ultra-short Period Super-Mercury Candidate

We present a reanalysis of the K2-106 transiting planetary system, with a focus on the composition of K2-106b, an ultra-short period, super-Mercury candidate. We globally model existing photometric and radial velocity data and derive a planetary mass and radius for K2-106b of Mp=8.53±1.02 M⊕ and Rp=1.71+0.069−0.057 R⊕, which leads to a density of ρp=9.4+1.6−1.5 g cm−3, a significantly lower value than previously reported in the literature. We use planet interior models that assume a two-layer planet comprised of a liquid, pure Fe core and iron-free, MgSiO3 mantle, and we determine the range of core mass fractions that are consistent with the observed mass and radius. We use existing high-resolution spectra of the host star to derive Fe/Mg/Si abundances ([Fe/H]=−0.03±0.01, [Mg/H]=0.04±0.02, [Si/H]=0.03±0.06) to infer the composition of K2-106b. We find that although K2-106b has a high density and core mass fraction (44+12−15%) compared to the Earth (33%), its composition is consistent with what is expected assuming that it reflects the relative refractory abundances of its host star. K2-106b is therefore unlikely to be a super-Mercury, as has been suggested in previous literature.
https://arxiv.org/abs/2208.07883

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An Extrasolar World Covered in Water?
August 24, 2022

Introduction:

(EurekAlert) An international team of researchers led by Charles Cadieux, a Ph.D. student at the Université de Montréal and member of the Institute for Research on Exoplanets (iREx), has announced the discovery of TOI-1452 b, an exoplanet orbiting one of two small stars in a binary system located in the Draco constellation about 100 light-years from Earth.

The exoplanet is slightly greater in size and mass than Earth and is located at a distance from its star where its temperature would be neither too hot nor too cold for liquid water to exist on its surface. The astronomers believe it could be an “ocean planet,” a planet completely covered by a thick layer of water, similar to some of Jupiter’s and Saturn’s moons.

In an article published today in The Astronomical Journal, Cadieux and his team describe the observations that elucidated the nature and characteristics of this unique exoplanet.

“I’m extremely proud of this discovery because it shows the high calibre of our researchers and instrumentation,” said René Doyon, Université de Montréal Professor and Director of iREx and of the Observatoire du Mont-Mégantic (OMM). “It is thanks to the OMM, a special instrument designed in our labs called SPIRou, and an innovative analytic method developed by our research team that we were able to detect this one-of-a-kind exoplanet.”

It was NASA’s space telescope TESS, which surveys the entire sky in search of planetary systems close to our own, that put the researchers on the trail of this exoplanet. Based on the TESS signal, which showed a slight decrease in brightness every 11 days, astronomers predicted a planet about 70% larger than Earth.

Read more here: https://www.eurekalert.org/news-releases/962639

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NASA’s Webb Detects Carbon Dioxide in Exoplanet Atmosphere
https://www.nasa.gov/feature/goddard/20 ... atmosphere

NASA’s James Webb Space Telescope has captured the first clear evidence for carbon dioxide in the atmosphere of a planet outside the solar system. This observation of a gas giant planet orbiting a Sun-like star 700 light-years away provides important insights into the composition and formation of the planet. The finding, accepted for publication in Nature, offers evidence that in the future Webb may be able to detect and measure carbon dioxide in the thinner atmospheres of smaller rocky planets.

WASP-39 b is a hot gas giant with a mass roughly one-quarter that of Jupiter (about the same as Saturn) and a diameter 1.3 times greater than Jupiter. Its extreme puffiness is related in part to its high temperature (about 1,600 degrees Fahrenheit or 900 degrees Celsius). Unlike the cooler, more compact gas giants in our solar system, WASP-39 b orbits very close to its star – only about one-eighth the distance between the Sun and Mercury – completing one circuit in just over four Earth-days. The planet’s discovery, reported in 2011, was made based on ground-based detections of the subtle, periodic dimming of light from its host star as the planet transits, or passes in front of the star.

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NASA’s Webb Detects Carbon Dioxide in Exoplanet Atmosphere
https://www.nasa.gov/feature/goddard/20 ... atmosphere

NASA’s James Webb Space Telescope has captured the first clear evidence for carbon dioxide in the atmosphere of a planet outside the solar system. This observation of a gas giant planet orbiting a Sun-like star 700 light-years away provides important insights into the composition and formation of the planet. The finding, accepted for publication in Nature, offers evidence that in the future Webb may be able to detect and measure carbon dioxide in the thinner atmospheres of smaller rocky planets.

WASP-39 b is a hot gas giant with a mass roughly one-quarter that of Jupiter (about the same as Saturn) and a diameter 1.3 times greater than Jupiter. Its extreme puffiness is related in part to its high temperature (about 1,600 degrees Fahrenheit or 900 degrees Celsius). Unlike the cooler, more compact gas giants in our solar system, WASP-39 b orbits very close to its star – only about one-eighth the distance between the Sun and Mercury – completing one circuit in just over four Earth-days. The planet’s discovery, reported in 2011, was made based on ground-based detections of the subtle, periodic dimming of light from its host star as the planet transits, or passes in front of the star.

Life!?

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Two planets orbiting nearby star discovered with TESS
https://phys.org/news/2022-08-planets-o ... -tess.html
by Tomasz Nowakowski , Phys.org

Using the Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered two new exoplanets orbiting a nearby star known as TOI-836. The newfound alien worlds were classified as a super-Earth and a mini-Neptune. The finding is reported in a paper published August 15 on arXiv.org.

TESS is conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets. So far, it has identified over 5,800 candidate exoplanets (TESS Objects of Interest, or TOI), of which 233 have been confirmed so far.

Now, a team of astronomers led by Faith Hawthorn of the University of Warwick, U.K., confirms another two exoworlds monitored by TESS. They report that transit signals have been identified in the light curve of TOI-836 (or TIC 440887364)—a K-dwarf star located some 90 light years away. The planetary nature of these signals was confirmed by follow-up observations using ESA's CHaracterizing ExOPlanet Satellite (CHEOPS) and various ground-based facilities.

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NASA’s Webb Detects Carbon Dioxide in Exoplanet Atmosphere
https://www.nasa.gov/feature/goddard/20 ... atmosphere

NASA’s James Webb Space Telescope has captured the first clear evidence for carbon dioxide in the atmosphere of a planet outside the solar system. This observation of a gas giant planet orbiting a Sun-like star 700 light-years away provides important insights into the composition and formation of the planet. The finding, accepted for publication in Nature, offers evidence that in the future Webb may be able to detect and measure carbon dioxide in the thinner atmospheres of smaller rocky planets.

WASP-39 b is a hot gas giant with a mass roughly one-quarter that of Jupiter (about the same as Saturn) and a diameter 1.3 times greater than Jupiter. Its extreme puffiness is related in part to its high temperature (about 1,600 degrees Fahrenheit or 900 degrees Celsius). Unlike the cooler, more compact gas giants in our solar system, WASP-39 b orbits very close to its star – only about one-eighth the distance between the Sun and Mercury – completing one circuit in just over four Earth-days. The planet’s discovery, reported in 2011, was made based on ground-based detections of the subtle, periodic dimming of light from its host star as the planet transits, or passes in front of the star.

Life!?

co2 doesn't mean life. mars and venus have atmospheres that are both 90% co2 but they don't have any life on them.

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Webb takes its first exoplanet image
01/09/2022 1458 views 58 likes 470244 ID

For the first time, astronomers have used the NASA/ESA/CSA James Webb Space Telescope to take a direct image of an exoplanet. The exoplanet is a gas giant, meaning it has no rocky surface and could not be habitable. The image, as seen through four different light filters, shows how Webb’s powerful infrared gaze can easily capture worlds beyond our Solar System, pointing the way to future observations that will reveal more information than ever before about exoplanets.

The exoplanet in Webb’s image, called HIP 65426 b, is about six to eight times the mass of Jupiter. It is young as planets go – about 15 to 20 million years old, compared to our 4.5-billion-year-old Earth.

https://www.esa.int/ESA_Multimedia/Imag ... anet_image

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First full 3D view of binary star-planet system from VLBA

by National Radio Astronomy Observatory
https://phys.org/news/2022-09-full-3d-v ... lanet.html

By precisely tracing a small, almost imperceptible, wobble in a nearby star's motion through space, astronomers have discovered a Jupiter-like planet orbiting that star, which is one of a binary pair. Their work, using the National Science Foundation's Very Long Baseline Array (VLBA), produced the first-ever determination of the complete, 3-dimensional structure of the orbits of a binary pair of stars and a planet orbiting one of them. This achievement, the astronomers said, can provide valuable new insights on the process of planet formation.

Though more than 5,000 extrasolar planets have been discovered so far, only three have been discovered using the technique—called astrometry—that produced this discovery. However, the feat of determining the 3D architecture of a binary-star system that includes a planet "cannot be achieved with other exoplanet discovery methods," said Salvador Curiel, of the National Autonomous University of Mexico (UNAM).

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'Diamond rain' on giant icy planets could be more common than previously thought

September 2, 2022

A new study has found that "diamond rain," a long-hypothesized exotic type of precipitation on ice giant planets, could be more common than previously thought.

In an earlier experiment, researchers mimicked the extreme temperatures and pressures found deep inside ice giants Neptune and Uranus and, for the first time, observed diamond rain as it formed.

Investigating this process in a new material that more closely resembles the chemical makeup of Neptune and Uranus, scientists from the Department of Energy's SLAC National Accelerator Laboratory and their colleagues discovered that the presence of oxygen makes diamond formation more likely, allowing them to form and grow at a wider range of conditions and throughout more planets.

The new study provides a more complete picture of how diamond rain forms on other planets and, here on Earth, could lead to a new way of fabricating nanodiamonds, which have a very wide array of applications in drug delivery, medical sensors, noninvasive surgery, sustainable manufacturing, and quantum electronics.

"The earlier paper was the first time that we directly saw diamond formation from any mixtures," said Siegfried Glenzer, director of the High Energy Density Division at SLAC. "Since then, there have been quite a lot of experiments with different pure materials. But inside planets, it's much more complicated; there are a lot more chemicals in the mix. And so, what we wanted to figure out here was what sort of effect these additional chemicals have."

https://phys.org/news/2022-09-diamond-g ... ommon.html

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Birmingham telescope discovers two new temperate rocky worlds
https://phys.org/news/2022-09-birmingha ... orlds.html
by University of Birmingham

An international research team including astronomers at the University of Birmingham, has just announced the discovery of two "super-Earth" planets orbiting LP 890-9, a small, cool star located about 100 light-years from Earth.

The star, also called TOI-4306 or SPECULOOS-2, is the second-coolest star found to host planets, after the famous TRAPPIST-1. This rare discovery is the subject of a forthcoming publication in the journal Astronomy & Astrophysics.

The system's inner planet, called LP 890-9b, is about 30% larger than Earth and completes an orbit around the star in just 2.7 days. This first planet was initially identified as a possible planet candidate by NASA's Transiting Exoplanet Survey Satellite (TESS), a space mission searching for exoplanets orbiting nearby stars. This candidate was confirmed and characterized by the SPECULOOS telescopes (Search for habitable Planets EClipsing ULtra-cOOl Stars), one of which is operated by the University of Birmingham. SPECULOOS researchers then used their telescopes to seek additional transiting planets in the system that would have been missed by TESS.

"TESS searches for exoplanets using the transit method, by monitoring the brightness of thousands of stars simultaneously, looking for slight dimmings that might be caused by planets passing in front of their stars," explains Laetitia Delrez, a postdoctoral researcher at the University of Liège, and the lead author of the article.

"However, a follow-up with ground-based telescopes is often necessary to confirm the planetary nature of the detected candidates and to refine the measurements of their sizes and orbital properties."

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Surprise finding suggests 'water worlds' are more common than we thought
https://phys.org/news/2022-09-worlds-co ... ought.html
by University of Chicago

Water is the one thing all life on Earth needs, and the cycle of rain to river to ocean to rain is an essential part of what keeps our planet's climate stable and hospitable. When scientists talk about where to search for signs of life throughout the galaxy, planets with water are always at the top of the list.

A new study published in Science suggests that many more planets may have large amounts of water than previously thought—as much as half water and half rock. The catch? All that water is probably embedded in the rock, rather than flowing as oceans or rivers on the surface.

"It was a surprise to see evidence for so many water worlds orbiting the most common type of star in the galaxy," said Rafael Luque, first author on the new paper and a postdoctoral researcher at the University of Chicago. "It has enormous consequences for the search for habitable planets."

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It's a planet: New evidence of baby planet in the making
https://phys.org/news/2022-09-planet-evidence-baby.html
by Harvard-Smithsonian Center for Astrophysics

Astronomers agree that planets are born in protoplanetary disks—rings of dust and gas that surround young, newborn stars. While hundreds of these disks have been spotted throughout the universe, observations of actual planetary birth and formation have proved difficult within these environments.

Now, astronomers at the Center for Astrophysics | Harvard & Smithsonian have developed a new way to detect these elusive newborn planets—and with it, "smoking gun" evidence of a small Neptune or Saturn-like planet lurking in a disk. The results are described today in The Astrophysical Journal Letters.

"Directly detecting young planets is very challenging and has so far only been successful in one or two cases," says Feng Long, a postdoctoral fellow at the Center for Astrophysics who led the new study. "The planets are always too faint for us to see because they're embedded in thick layers of gas and dust."

Scientists instead must hunt for clues to infer a planet is developing beneath the dust.

"In the past few years, we've seen many structures pop up on disks that we think are caused by a planet's presence, but it could be caused by something else, too," Long says. "We need new techniques to look at and support that a planet is there."

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Techniques learned from Earth climate science aid in the search for potentially habitable exoplanets
https://phys.org/news/2022-09-technique ... e-aid.html
by University of Exeter

An international team, including astrophysicists from the University of Exeter, is taking lessons and techniques learned from Earth climate science to pave the way to robustly model atmospheres of planets orbiting distant stars, aiding in the search for potentially habitable exoplanets.

Crucially, the team believes that this research can also enhance our fundamental understanding and predictions of future climate on Earth.

The recently launched James Webb Space Telescope (JWST) and upcoming telescopes such as the European Extremely Large Telescope (E-ELT), the Thirty Meter Telescope (TMT) or the Giant Magellan Telescope (GMT) may soon be able to characterize the atmospheres of rocky exoplanets orbiting nearby red dwarfs (stars cooler and smaller than our own sun). However, without robust models to interpret and guide these observations we will not be able to unlock the full potential of these observatories.

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New exoplanet detection program for citizen scientists
https://phys.org/news/2022-09-exoplanet ... tists.html
by SETI Institute

The SETI Institute and its partner Unistellar are launching a new exoplanet detection program that will engage citizen scientists worldwide. Amateur astronomers, using either Unistellar's eVscope or another telescope, will be invited to help confirm exoplanet candidates identified by NASA's Transiting Exoplanet Survey Satellite (TESS) by observing possible exoplanet transits from Earth.

Most known exoplanets have been detected using the transit method, most notably by the Kepler Mission and now TESS. A transit is when a planet passes between its star and the observer, who will see the star dimming as the planet orbits. The demand for follow-up observations of transiting exoplanets is greater than ever. There are currently more than 5,100 confirmed exoplanets, with thousands more detections to be confirmed. This program will focus its efforts on exo-Jupiters detected by those NASA missions.

Some estimates suggest that TESS will identify more than 10,000 exoplanet candidates. Follow-up observations are essential for unconfirmed exoplanets to determine if candidates are false positives, such as those caused by eclipsing binaries or transits of low-mass stars. Regular re-observations by ground-based systems are necessary for confirmed planets to keep their orbital ephemerides updated. The potential for citizen scientist contribution to exoplanet science is high and has exciting implications for STEM education.