Exoplanets – worlds of other suns

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Re: Exoplanets – worlds of other suns

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Two massive Jupiter-sized exoplanets discovered with TESS
Image
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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caltrek
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Re: Exoplanets – worlds of other suns

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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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caltrek
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Re: Exoplanets – worlds of other suns

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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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Re: Exoplanets – worlds of other suns

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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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Re: Exoplanets – worlds of other suns

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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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Re: Exoplanets – worlds of other suns

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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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Re: Exoplanets – worlds of other suns

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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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Re: Exoplanets – worlds of other suns

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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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Re: Exoplanets – worlds of other suns

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weatheriscool wrote: Thu Aug 25, 2022 4:26 pm 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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