Exoplanets – worlds of other suns

[wjfox]

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.

[wjfox]

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.

[weatheriscool]

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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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

[wjfox]

[weatheriscool]

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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Kepler telescope delivers new planetary discovery from the grave
https://phys.org/news/2022-04-kepler-te ... grave.html
by Jodrell Bank Centre for Astrophysics

A new study by an international team of astrophysicists, led by the Jodrell Bank Center for Astrophysics has presented the amazing new discovery of a near-identical twin of Jupiter orbiting a star at a colossal distance of 17,000 light years from Earth.

The exoplanet, K2-2016-BLG-0005Lb, is almost identical to Jupiter in terms of its mass and distance from the sun, was discovered using data obtained in 2016 by NASA's Kepler space telescope. The exoplanetary system is twice as distant as any seen previously by Kepler, which found over 2,700 confirmed planets before ceasing operations in 2018.

The system was found using gravitational microlensing, a prediction of Einstein's Theory of Relativity, and is the first planet to be discovered from space in this way. The study has been submitted to the journal Monthly Notices of the Royal Astronomical Society and has been made available as a preprint on ArXiv.org.

Ph.D. student, David Specht from The University of Manchester is the lead author on the new research. To find an exoplanet using the microlensing effect the team searched through Kepler data collected between April and July 2016 when it regularly monitored millions of stars close to the center of the Galaxy. The aim was to look for evidence of an exoplanet and its host star temporarily bending and magnifying the light from a background star as it passes by the line of sight.

[caltrek]

Hubble Probes Extreme Weather on Ultra-hot Jupiters
April 6, 2022

https://www.eurekalert.org/news-releases/948943

Introduction:

(EurekAlert) In studying a unique class of ultra-hot exoplanets, NASA Hubble Space Telescope astronomers may be in the mood for dancing to the Calypso party song "Hot, Hot, Hot." That's because these bloated Jupiter-sized worlds are so precariously close to their parent star they are being roasted at seething temperatures above 3,000 degrees Fahrenheit. That's hot enough to vaporize most metals, including titanium. They have the hottest planetary atmospheres ever seen.

In two new papers, teams of Hubble astronomers are reporting on bizarre weather conditions on these sizzling worlds. It's raining vaporized rock on one planet, and another one has its upper atmosphere getting hotter rather than cooler because it is being "sunburned" by intense ultraviolet (UV) radiation from its star.

This research goes beyond simply finding weird and quirky planet atmospheres. Studying extreme weather gives astronomers better insights into the diversity, complexity, and exotic chemistry taking place in far-flung worlds across our galaxy.

"We still don't have a good understanding of weather in different planetary environments," said David Sing of the Johns Hopkins University in Baltimore, Maryland, co-author on two studies being reported. "When you look at Earth, all our weather predictions are still finely tuned to what we can measure. But when you go to a distant exoplanet, you have limited predictive powers because you haven't built a general theory about how everything in an atmosphere goes together and responds to extreme conditions. Even though you know the basic chemistry and physics, you don't know how it's going to manifest in complex ways."

In a paper in the April 7 journal Nature, astronomers describe Hubble observations of WASP-178b, located about 1,300 light-years away. On the daytime side the atmosphere is cloudless, and is enriched in silicon monoxide gas. Because one side of the planet permanently faces its star, the torrid atmosphere whips around to the nighttime side at super-hurricane speeds exceeding 2,000 miles per hour. On the dark side, the silicon monoxide may cool enough to condense into rock that rains out of clouds, but even at dawn and dusk, the planet is hot enough to vaporize rock. "We knew we had seen something really interesting with this silicon monoxide feature," said Josh Lothringer of the Utah Valley University in Orem, Utah

[weatheriscool]

Hubble Probes Extreme Weather on Ultra-hot Jupiters
April 6, 2022

https://www.eurekalert.org/news-releases/948943

Introduction:

(EurekAlert) In studying a unique class of ultra-hot exoplanets, NASA Hubble Space Telescope astronomers may be in the mood for dancing to the Calypso party song "Hot, Hot, Hot." That's because these bloated Jupiter-sized worlds are so precariously close to their parent star they are being roasted at seething temperatures above 3,000 degrees Fahrenheit. That's hot enough to vaporize most metals, including titanium. They have the hottest planetary atmospheres ever seen.

In two new papers, teams of Hubble astronomers are reporting on bizarre weather conditions on these sizzling worlds. It's raining vaporized rock on one planet, and another one has its upper atmosphere getting hotter rather than cooler because it is being "sunburned" by intense ultraviolet (UV) radiation from its star.

This research goes beyond simply finding weird and quirky planet atmospheres. Studying extreme weather gives astronomers better insights into the diversity, complexity, and exotic chemistry taking place in far-flung worlds across our galaxy.

"We still don't have a good understanding of weather in different planetary environments," said David Sing of the Johns Hopkins University in Baltimore, Maryland, co-author on two studies being reported. "When you look at Earth, all our weather predictions are still finely tuned to what we can measure. But when you go to a distant exoplanet, you have limited predictive powers because you haven't built a general theory about how everything in an atmosphere goes together and responds to extreme conditions. Even though you know the basic chemistry and physics, you don't know how it's going to manifest in complex ways."

In a paper in the April 7 journal Nature, astronomers describe Hubble observations of WASP-178b, located about 1,300 light-years away. On the daytime side the atmosphere is cloudless, and is enriched in silicon monoxide gas. Because one side of the planet permanently faces its star, the torrid atmosphere whips around to the nighttime side at super-hurricane speeds exceeding 2,000 miles per hour. On the dark side, the silicon monoxide may cool enough to condense into rock that rains out of clouds, but even at dawn and dusk, the planet is hot enough to vaporize rock. "We knew we had seen something really interesting with this silicon monoxide feature," said Josh Lothringer of the Utah Valley University in Orem, Utah

It's insane how the typical solar system is being found with so many of these close in jupiters that are extremely hot. One theory for this is they developed further out and moved in destroying all the rocky planets as they did so...This kind of sucks for the possibility for life outside of our solar system. Anyways, the winds on such a hot jupiter must be many thousands of miles per hour and it would be fun to image one day.

[weatheriscool]

Two new Saturn-mass exoplanets discovered

by Tomasz Nowakowski, Science X Network, Phys.org
https://phys.org/news/2022-04-saturn-ma ... anets.html

An international team of astronomers reports the detection of two new Saturn-mass exoplanets as part of the CARMENES radial velocity survey. The newly found alien worlds, designated TYC 2187-512-1 b and TZ Ari b, orbit nearby M-dwarf stars. The finding was presented in a paper published March 30 on arXiv.org.

Thanks to the radial velocity (RV) technique, more than 600 exoplanets have been detected so far and more than 100 of them have been found around M dwarfs. The Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs (CARMENES) project has been crucial in the search for new alien worlds orbiting these most common stars in our galaxy.

Recently, a group of researchers led by Andreas Quirrenbach of Heidelberg University in Germany has announced the discovery of another two extrasolar worlds as part of the CARMENES survey. The observations conducted with the 3.5 m telescope at the Calar Alto observatory in Almería, Spain, have confirmed that two nearby M dwarfs, TYC 2187-512-1 and TZ Ari, host massive planets.

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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

Quote :

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.

Tuomi (2019) also claimed the presence of a planet at this star.

[weatheriscool]

Team behind discovery of planet with three stars retracts their article
https://phys.org/news/2022-04-team-disc ... racts.html
by Bob Yirka , Phys.org

An international team of researchers who published a paper in the journal Science in 2016 describing their discovery of an exoplanet with three stars, has now retracted that paper.

In their original paper, the team described their work with direct imaging technology to study the triple-star system HD 131399. They spotted what they believed to be an exoplanet approximately four times the size of Jupiter. They also noted its apparent odd orbital system—the planet appeared to orbit just one of the stars while the other two stars were farther away.

Subsequent to the publishing of the paper, in 2017, another international team of researchers found evidence suggesting that the planet was not a planet after all—the data observed the year before, they claimed, was from a background object, perhaps a dwarf star. They further noted in their paper published in The Astronomical Journal, that the object was much more likely to be something moving unusually fast in the background in a path that coincided with star system HD 131399.

[weatheriscool]

Second alien world detected in the planetary system HD 83443

by Tomasz Nowakowski , Phys.org
https://phys.org/news/2022-04-alien-wor ... ry-hd.html

Astronomers report the discovery of another exoplanet around a nearby star known as HD 83443. The newfound extrasolar world is a Jupiter-mass planet orbiting its host on a highly eccentric 22-year orbit. The finding was detailed in a paper published April 12 on the arXiv pre-print server.

Located some 133 light years away, HD 83443 is a solar mass K0 star, with more than twice the metallicity of the sun. The age of this star is estimated to be 2.64 billion years and its effective temperature is around 5,429 K. HD 83443 is known to host a "hot Jupiter" exoplanet (designated HD 83443 b), with a mass of some 0.41 Jupiter masses, which orbits it approximately every three days.

Now, a team of astronomers led by Adriana Errico of the University of Southern Queensland in Australia, reports the detection of another giant planet orbiting HD 83443, which was suggested by previous studies. The finding is a result of analyzing radial velocity data from four instruments, namely: the University College London Echelle Spectrograph (UCLES) at the 3.9 m Anglo-Australian Telescope (AAT), the High Resolution Echelle Spectrometer (HIRES) at the Keck Telescope, the High Accuracy Radial velocity Planet Searcher (HARPS) at the ESO La Silla 3.6m telescope, and also the MINERVA-Australis telescope array at the Mount Kent Observatory.

"HD 83443 has been observed by four precise radial velocity instruments spanning a baseline of over 22 years. Here we give details about the observations from each instrument," the researchers wrote in the paper.

[weatheriscool]

The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc
https://arxiv.org/abs/2204.10261
Quote :

We report the discovery of a multi-planetary system transiting the M0 V dwarf HD 260655 (GJ 239, TOI-4599). The system consists of at least two transiting planets, namely HD 260655 b, with a period of 2.77 d, a radius of Rb = 1.240±0.023 R⊕, a mass of Mb = 2.14±0.34 M⊕, and a bulk density of ρb = 6.2±1.0 g cm−3, and HD 260655 c, with a period of 5.71 d, a radius of Rc = 1.533+0.051−0.046 R⊕, a mass of Mc = 3.09±0.48 M⊕, and a bulk density of ρc = 4.7+0.9−0.8 g cm−3. The planets were detected in transit by the TESS mission and confirmed independently with archival and new precise radial velocities obtained with the HIRES and CARMENES instruments since 1998 and 2016, respectively. At a distance of 10 pc, HD 260655 becomes the fourth closest known multi-transiting planet system after HD 219134, LTT 1445 A, and AU Mic. Due to the apparent brightness of the host star (J = 6.7 mag), both planets are among the most suitable rocky worlds known today for atmospheric studies with the JWST, both in transmission and emission.

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A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system
https://arxiv.org/abs/2204.13573

It is commonly accepted that exoplanets with orbital periods shorter than 1 day, also known as ultra-short period (USP) planets, formed further out within their natal protoplanetary disk, before migrating to their current-day orbits via dynamical interactions. One of the most accepted theories suggests a violent scenario involving high-eccentricity migration followed by tidal circularization. Here, we present the discovery of a four planet system orbiting the bright (V=10.5) K6 dwarf star TOI-500. The innermost planet is a transiting, Earth-sized USP planet with an orbital period of ∼ 13 hours, a mass of 1.42 ± 0.18 M⊕, a radius of 1.166+0.061−0.058 R⊕, and a mean density of 4.89+1.03−0.88 gcm−3. Via Doppler spectroscopy, we discovered that the system hosts three outer planets on nearly circular orbits with periods of 6.6, 26.2, and 61.3d and minimum masses of 5.03 ± 0.41 M⊕, 33.12 ± 0.88 M⊕ and 15.05+1.12−1.11 M⊕, respectively. The presence of both a USP planet and a low-mass object on a 6.6-day orbit indicates that the architecture of this system can be explained via a scenario in which the planets started on low-eccentricity orbits, then moved inwards through a quasi-static secular migration. Our numerical simulations show that this migration channel can bring TOI-500 b to its current location in 2 Gyrs, starting from an initial orbit of 0.02au. TOI-500 is the first four planet system known to host a USP Earth analog whose current architecture can be explained via a non-violent migration scenario.

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Two rocky exoplanets discovered around nearby star
https://phys.org/news/2022-04-rocky-exo ... -star.html
by Tomasz Nowakowski , Phys.org

Using NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers have detected two rocky alien worlds orbiting a nearby M dwarf star known as HD 260655. The newly found exoplanets are larger and at least two times more massive than the Earth. The finding is reported in a paper published April 21 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 5,600 candidate exoplanets (TESS Objects of Interest, or TOI), of which 205 have been confirmed so far.

Now, a team of astronomers led by Rafael Luque of the University of Chicago confirmed another two planets monitored by TESS. They report that transit signals have been identified in the light curve of the bright M dwarf HD 260655 (or TOI-4599). The planetary nature of these signals was confirmed by archival and new precise radial velocity (RV) measurements.

"This work presents the discovery and characterization of a multiplanetary system orbiting the nearby M dwarf HD 260655. Transit observations from TESS detected two small planet candidates that were confirmed with independent RV data from the HIRES and CARMENES instruments taken since 1998 and 2016, respectively," the researchers wrote in the paper.