Exoplanets – worlds of other suns

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Re: Exoplanets – worlds of other suns

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New planet detected around closest star

10th February 2022

A third planet has been detected orbiting Proxima Centauri, the nearest star to our Sun. Proxima d, with only a quarter of Earth's mass, is one of the lightest exoplanets ever found.

https://www.futuretimeline.net/blog/202 ... meline.htm


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Hot Earth-sized exoplanet detected with TESS
https://phys.org/news/2022-02-hot-earth ... -tess.html
by Tomasz Nowakowski , Phys.org
Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a new Earth-sized planet orbiting a nearby star. The newly found alien world, designated GJ 3929 b, is slightly larger and more massive than the Earth, however much hotter than our home planet. The finding was presented in a paper published February 2 on the arXiv pre-print server.

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 5,200 candidate exoplanets (TESS Objects of Interest, or TOI), of which 180 have been confirmed so far.

A team of astronomers led by Jonas Kemmer of the Heidelberg University in Germany has recently confirmed another TOI monitored by TESS. They report that a transit signal has been identified in the light curve of an M dwarf star known as GJ 3929 (other designations: G 180–18, TOI-2013). The planetary nature of this signal was confirmed by follow-up observations, using mainly the CARMENES spectrograph.

"In this study, we present the discovery of a hot Earth-sized planet orbiting the M3.5 V-dwarf star, GJ 3929. Based on transit signals observed by TESS, we performed an intensive RV follow-up campaign with CARMENES to confirm its planetary origin," the researchers wrote in the paper.

GJ 3929 b has a radius of about 1.15 Earth radii and its mass is approximately 1.21 Earth masses, thus the planet's density is calculated to be 4.4 g/cm3. The exoworld orbits its parent star every 2.61 days, at a distance of about 0.0026 AU from it. The equilibrium temperature of this planet is estimated to be 569 K.

The astronomers noted that the high equilibrium temperature of GJ 3929 b makes it a prime target for atmospheric follow-up observations. Such studies, using instruments like the James Webb Space Telescope (JWST) could deliver important information regarding the composition and, thus, formation and evolution of small and rocky planets.
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Re: Exoplanets – worlds of other suns

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Life could exist on planet orbiting 'white dwarf' star

2 hours ago

Researchers believe there may be a planet that could sustain life, in the vicinity of a dying sun.

If confirmed, this would be the first time that a potentially life-supporting planet has been found orbiting such a star, called a "white dwarf".

The planet was detected in the star's "habitable zone", where it's neither too cold nor too hot to sustain life.

The study is published in the monthly notices of the Royal Astronomical Society.

Prof Jay Farihi of University College London, who led the study, said the observation was completely new to astronomers.

"This is the first time that anything has been seen in the habitable zone of a white dwarf. And thus there is a possibility of life on another world orbiting it," he told BBC News.

https://www.bbc.co.uk/news/science-environment-60325010
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A "hot Jupiter's" dark side is revealed in detail for first time
https://phys.org/news/2022-02-hot-jupit ... ealed.html
by Jennifer Chu, Massachusetts Institute of Technology
MIT astronomers have obtained the clearest view yet of the perpetual dark side of an exoplanet that is "tidally locked" to its star. Their observations, combined with measurements of the planet's permanent day side, provide the first detailed view of an exoplanet's global atmosphere.

"We're now moving beyond taking isolated snapshots of specific regions of exoplanet atmospheres, to study them as the 3D systems they truly are," says Thomas Mikal-Evans, who led the study as a postdoc in MIT's Kavli Institute for Astrophysics and Space Research.

The planet at the center of the new study, which appears in Nature Astronomy, is WASP-121b, a massive gas giant nearly twice the size of Jupiter. The planet is an ultrahot Jupiter and was discovered in 2015 orbiting a star about 850 light years from Earth. WASP-121b has one of the shortest orbits detected to date, circling its star in just 30 hours. It is also tidally locked, such that its star-facing "day" side is permanently roasting, while its "night" side is turned forever toward space.
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New brown dwarf discovered with TESS
https://phys.org/news/2022-02-brown-dwarf-tess.html
by Tomasz Nowakowski , Phys.org

Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has detected a new brown dwarf. The newly found object, designated TOI-2119b, turns out to be about the size of Jupiter but over 60 times more massive than the solar system's biggest planet. The discovery is reported in a paper published February 17 on arXiv.org.

Brown dwarfs are intermediate objects between planets and stars, occupying the mass range between 13 and 80 Jupiter masses. Although many brown dwarfs have been detected to date, such objects orbiting other stars are a rare find.

Now, a group of astronomers led by Theron W. Carmichael of the University of Edinburgh, UK, reports the finding of another rare brown dwarf transiting an M-dwarf star. To date, only eight such systems have been detected.

Carmichael's team have employed TESS to observe a nearby active M dwarf known as TOI-2119 (other designation TIC 236387002), which is located some 103.7 light years away from the Earth. A transit signal was found in the light curve of this star and a follow-up observational campaign has confirmed the brown dwarf nature of this signal.
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Scaling K2. V. Statistical Validation of 60 New Exoplanets From K2 Campaigns 2-18
The NASA K2 mission, salvaged from the hardware failures of the Kepler telescope, has continued Kepler's planet-hunting success. It has revealed nearly 500 transiting planets around the ecliptic plane, many of which are the subject of further study, and over 1000 additional candidates. Here we present the results of an ongoing project to follow-up and statistically validate new K2 planets, in particular to identify promising new targets for further characterization. By analyzing the reconnaissance spectra, high-resolution imaging, centroid variations, and statistical likelihood of the signals of 91 candidates, we validate 60 new planets in 46 systems. These include: a number of planets amenable to transmission spectroscopy (K2-384 f, K2-387 b, K2-390 b, K2-403 b, and K2-398 c), emission spectroscopy (K2-371 b, K2-370 b, and K2-399 b), and both (K2-405 b and K2-406 b); several systems with planets in or close to mean motion resonances (K2-381, K2-398) including a compact, TRAPPIST-1-like system of five small planets orbiting a mid-M dwarf (K2-384); an ultra-short period sub-Saturn in the hot Saturn desert (K2-399 b); and a super-Earth orbiting a moderately bright (V=11.93), metal-poor ([Fe/H]=-0.579+/-0.080) host star (K2-408 b). In total we validate planets around 4 F stars, 26 G stars, 13 K stars, and 3 M dwarfs. In addition, we provide a list of 37 vetted planet candidates that should be prioritized for future follow-up observation in order to be confirmed or validated.
https://arxiv.org/abs/2203.02087
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The start of the birth of planets in a binary star system observed
https://phys.org/news/2022-03-birth-pla ... -star.html
by University of Manchester
Astronomers have observed primordial material that may be giving birth to three planetary systems around a binary star in unprecedented detail.

Bringing together three decades of study, an international group of scientists have observed a pair of stars orbiting each other, to reveal that these stars are surrounded by disks of gas and dust. Research published today in The Astrophysical Journal, shows the material within the newly discovered disks could be the beginnings of new planet systems which in the future orbit the binary stars.

Using the Very Large Array (VLA) and the Atacama Large Millimeter/Submillimeter Array (ALMA), the scientific group has studied the binary star SVS 13, still in its embryonic phase. This work has provided the best description available so far on a binary system in formation.

Models of planet formation suggest that planets form by the slow aggregation of ice and dust particles in protoplanetary disks around forming stars. Usually these models consider only single stars, such as the sun. However, most stars form binary systems, in which two stars rotate around a common center. Very little is yet known about how planets are born around these important twin star systems, in which the gravitational interaction between the two stars plays an essential role.

"Our results have revealed that each star has a disk of gas and dust around it and that, in addition, a larger disk is forming around both stars," says Ana Karla Díaz-Rodríguez, a researcher at the IAA-CSIC and the UK ALMA Regional Center (UK-ARC) at The University of Manchester, who leads the work.
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Re: Exoplanets – worlds of other suns

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Cacciapuoti et al. (2022) "The TESS Triple-9 Catalog: 999 uniformly-vetted exoplanet candidates"
https://doi.org/10.1093/mnras/stac652

Excerpt from the abstract:

Quote :
More than 70 per cent of the TOIs listed in the TT9 pass our diagnostic tests, and are thus marked as true planetary candidates. We flagged 144 candidates as false positives, and identified 146 as potential false positives. At the time of writing, the TT9 catalog contains ∼20 per cent of the entire ExoFOP-TESS TOIs list
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Re: Exoplanets – worlds of other suns

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New Jupiter-sized exoplanet discovered with TESS
https://phys.org/news/2022-03-jupiter-s ... -tess.html
by Tomasz Nowakowski , Phys.org
Using NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers from the Pennsylvania State University (PSU) and elsewhere have detected a new Jupiter-sized extrasolar world. The newfound exoplanet, designated TOI-3757 b, is slightly larger than Jupiter but more than three times less massive than the solar system's biggest planet. The finding is reported in a paper published March 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. It has identified over 5,400 candidate exoplanets (TESS Objects of Interest, or TOI), of which 199 have been confirmed so far.

A group of astronomers led by PSU's Shubham Kanodia has recently confirmed another TOI monitored by TESS. They report that a transit signal has been identified in the light curve of an M dwarf star known as TOI-3757. The planetary nature of this signal was confirmed by follow-up observations.
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