Exoplanets – worlds of other suns

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Astronomers discover an unusually low-density super-Earth
https://phys.org/news/2023-05-astronome ... earth.html
by Tomasz Nowakowski , Phys.org

An international team of astronomers reports the detection of a new "super-Earth" exoplanet using NASA's Transiting Exoplanet Survey Satellite (TESS). The newfound alien world, designated TOI-244 b, turns out to have an unusually low density. The finding was reported in a paper published May 8 on the arXiv preprint 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 nearly 6,600 candidate exoplanets (TESS Objects of Interest, or TOI), of which 331 have been confirmed so far.

Now, a group of astronomers led by Amadeo Castro-González of the Spanish Astrobiology Center in Madrid, Spain, has confirmed another TOI monitored by TESS. They report that a transit signal was detected in the light curve of TOI-244 (also known as GJ 1018)—a nearby bright, early type M-dwarf star of spectral type M2.5 V, nearly half the size and mass of the sun. The planetary nature of this signal was confirmed by radial velocity measurements conducted with the ESPRESSO spectrograph mounted on the European Southern Observatory's Very Large Telescope (VLT) in Chile.

"Based on the transit signal detected from TESS data, we carried out an intensive radial velocity campaign with ESPRESSO in order to confirm its planetary nature, obtain a precise mass measurement, as well as to search for additional planets," the researchers wrote.

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Volcanoes may carpet surface of newfound Earth-size exoplanet
By Mike Wall published about 3 hours ago

Volcanic activity on the alien world, which lies about 90 light-years from Earth, may generate an atmosphere.

A newfound alien world about the size of Earth may be studded with active volcanoes, whose emissions could sustain an atmosphere, a new study reports.

The exoplanet, known as LP 791-18 d, orbits a red dwarf star about 90 light-years from Earth, in the southern constellation Crater. It's slightly larger and more massive than Earth, according to the study team — and it's probably much more volcanically active than our planet.

"LP 791-18 d is tidally locked, which means the same side constantly faces its star," co-author Björn Benneke, an astronomy professor at the University of Montreal's Institute for Research on Exoplanets who planned and supervised the study, said in a statement.

"The day side would probably be too hot for liquid water to exist on the surface," Benneke said. "But the amount of volcanic activity we suspect occurs all over the planet could sustain an atmosphere, which may allow water to condense on the night side."

More:
https://www.space.com/earth-size-exopla ... tification

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Astronomers discover a key planetary system for understanding formation mechanism of mysterious 'super-Earths'
https://phys.org/news/2023-05-astronome ... anism.html
by University de Liege

A study led by researchers of the University of Liège and the CSIC—using observations from NASA's TESS telescope—presents the detection of a system of two planets slightly larger than Earth orbiting a cold star in a synchronized dance. Named TOI-2096, the system is located 150 light-years from Earth.

The discovery is the result of a close collaboration between European and American universities and was made possible by the US space mission TESS (Transiting Exoplanet Survey Satellite), which aims to find planets orbiting nearby bright stars.

"TESS is conducting an all-sky survey using the transit method, that is, monitoring the stellar brightness of thousands of stars in the search for a slight dimming, which could be caused by a planet passing between the star and the observer. However, despite its power to detect new worlds, the TESS mission needs support from ground-based telescopes to confirm the planetary nature of the detected signals," explains Francisco J. Pozuelos, astrophysicist, first author of the paper, former member of the ExoTIC laboratory at the Univeristy of Liège, and who has now joined the Spanish National Research Council (IAA-CSIC).

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New 'super-Neptune' exoplanet discovered with TESS
https://phys.org/news/2023-05-super-nep ... -tess.html
by Tomasz Nowakowski , Phys.org

Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a new hot, bloated "super-Neptune" exoplanet. The newfound alien world, designated TOI-2498 b, is about six times larger and 35 times more massive than the Earth. The finding was published May 16 in Monthly Notices of the Royal Astronomical Society.

TESS is conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets, ranging from small rocky worlds to gaseous giants. So far, it has identified nearly 6,600 candidate exoplanets (TESS Objects of Interest, or TOI), of which 331 have been confirmed to date.

One of the stars observed by TESS during its primary mission was TOI-2498 (also known as TIC-263179590)—a G-type solar-type star about 26% larger and 12% more massive than the sun. TESS monitored TOI-2498 between December 12, 2018, and January 6, 2019, which resulted in the detection of a transit signal in its light curve. Planetary nature of this signal was confirmed by follow-up spectroscopic and photometric observations conducted by astronomers led by Ginger Frame of the University of Warwick, U.K.

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One-third of Galaxy’s Most Common Planets Could be in Habitable Zone
May 29, 2023

Introduction:

(Eurekalert) Our familiar, warm, yellow sun is a relative rarity in the Milky Way. By far the most common stars are considerably smaller and cooler, sporting just half the mass of our sun at most. Billions of planets orbit these common dwarf stars in our galaxy.

To capture enough warmth to be habitable, these planets would need to huddle very close to their small stars, which leaves them susceptible to extreme tidal forces.

In a new analysis based on the latest telescope data, University of Florida astronomers have discovered that two-thirds of the planets around these ubiquitous small stars could be roasted by these tidal extremes, sterilizing them. But that leaves one-third of the planets – hundreds of millions across the galaxy – that could be in a goldilocks orbit close enough, and gentle enough, to hold onto liquid water and possibly harbor life.

UF astronomy professor Sarah Ballard and doctoral student Sheila Sagear published their findings the week of May 29 in the Proceedings of the National Academy of Sciences. Ballard and Sagear have long studied exoplanets, those worlds that orbit stars other than the sun.

“I think this result is really important for the next decade of exoplanet research, because eyes are shifting toward this population of stars,” Sagear said. “These stars are excellent targets to look for small planets in an orbit where it’s conceivable that water might be liquid and therefore the planet might be habitable.”

Read more here: https://www.eurekalert.org/news-releases/990505

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NIRISS instrument on Webb maps an ultra-hot Jupiter-like exoplanet's atmosphere

https://phys.org/news/2023-05-niriss-in ... -like.html
by University of Montreal
400 light-years out there is something that is so tantalizing that astronomers have been studying it since its discovery in 2009. One orbit for WASP-18 b around its star that is slightly larger than our sun takes just 23 hours. There is nothing like it in our solar system.

A new study led by Université de Montréal Ph.D. student Louis-Philippe Coulombe about this exoplanet, an ultra-hot gas giant 10 times more massive than Jupiter, based on new data from the Canadian NIRISS instrument on the James Webb Space Telescope (JWST) holds many surprises.
Mapping an exoplanet

An international team of astronomers have identified water vapor in the atmosphere of the exoplanet WASP-18 b and made a temperature map of the planet as it slipped behind, and reappeared from, its star. This event is known as a secondary eclipse. Scientists can read the combined light from the star and planet, then refine the measurements from just the star as the planet moves behind it.

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The TESS-Keck Survey. XV. Precise Properties of 108 TESS Planets and Their Host Stars
https://arxiv.org/abs/2306.00251

Several TOIs confirmed.

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Two Warm Neptunes transiting HIP 9618 revealed by TESS & Cheops
https://arxiv.org/abs/2306.04450

TESS and CHEOPS Discover Two Warm Sub-Neptunes Transiting the Bright K-dwarf HD 15906
https://arxiv.org/abs/2306.04511

Refined parameters of the HD 22946 planetary system and the true orbital period of planet d
https://arxiv.org/abs/2306.04468

TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS and HARPS
https://arxiv.org/abs/2306.04295

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TOI-4010: A System of Three Large Short-Period Planets With a Massive Long-Period Companion
https://arxiv.org/abs/2306.05308

The big difference between Kepler and tess is Kepler was finding earth and super earths like tess is finding neptunes and Saturn size planets. Tess was suppose to be better or something? I don't think so. I think it is less capable of finding smaller planets that maybe able to support life and has disappointed so far.

For 500 million if not a billion for a slightest upgraded kepler 2 we'd get vastly more. Of course that'll never happen. We could put up 3 or 4 and probably end up being better off for planet discovery then everything we've ever put up including probably most of the ground infrastructure for fucks sake.

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A new Tatooine-like multi-planetary system identified
https://phys.org/news/2023-06-tatooine- ... etary.html
by University of Birmingham

An international team of astronomers has announced the second-ever discovery of a multiplanetary circumbinary system.

Circumbinary systems contain planets that orbit around two stars in the center instead of just one, like in our solar system. Circumbinary planets orbit around both stars at once. The discovery, led by researchers at the University of Birmingham, is reported in the journal Nature Astronomy.

The newly discovered planet is called BEBOP-1c, after the name of the project that collected the data. BEBOP stands for Binaries Escorted By Orbiting Planets. The BEBOP-1 system is also known as TOI-1338.

In 2020, a circumbinary planet, called TOI-1338b, was discovered in the same system using data from NASA's TESS space telescope, to which the Birmingham team also contributed. That planet was discovered with the transit method and was noticed because it passed in front of the brighter of the two stars on several occasions.

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A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654
https://arxiv.org/abs/2306.08179

Two sub-Neptunes around the M dwarf TOI-1470
https://arxiv.org/abs/2306.08516

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Webb Telescope is powerful enough to see a variety of biosignatures in exoplanets, argues new paper

by Brian Koberlein, Universe Today

https://phys.org/news/2023-06-webb-tele ... tures.html

The best hope for finding life on another world isn't listening for coded messages or traveling to distant stars, it's detecting the chemical signs of life in exoplanet atmospheres. This long hoped-for achievement is often thought to be beyond our current observatories, but a new study argues that the James Webb Space Telescope (JWST) could pull it off.

Most of the exoplanets we've discovered so far have been found by the transit method. This is where a planet passes in front of its star from our point of view. Even though we can't observe the planet directly, we can see the star's brightness dip by a fraction of a percent. As we watch stars over time, we can find a regular pattern of brightness dips, indicating the presence of a planet.

The star dips in brightness because the planet blocks some of the starlight. But if the planet also has an atmosphere, there is a small amount of light that will pass through the atmosphere before reaching us. Depending on the chemical composition of the atmosphere, certain wavelengths will be absorbed, forming absorption spectra within the spectra of the starlight. We have long been able to identify atoms and molecules by their absorption and emission spectra, so in principle, we can determine a planet's atmospheric composition with the transit method.

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Webb rules out thick carbon dioxide atmosphere for rocky exoplanet
https://phys.org/news/2023-06-webb-thic ... phere.html
by NASA

Infrared measurements of TRAPPIST-1 c indicate that it is probably not as Venus-like as once imagined.

NASA's James Webb Space Telescope has successfully measured the heat radiating from TRAPPIST-1 c, an exoplanet orbiting a red dwarf star 40 light-years from Earth. With a dayside temperature of about 225 degrees Fahrenheit, it is the coolest rocky planet ever characterized using this method.

Unfortunately for those hoping that the TRAPPIST-1 system is a true analog to our own, the results are a bit disappointing. While TRAPPIST-1 c is roughly the same size and mass as Venus and receives the same amount of radiation from its star, it appears unlikely to have the same thick carbon dioxide atmosphere. This indicates that the planet, and perhaps the system as a whole, may have formed with very little water. The result is the latest in the quest to determine whether planetary atmospheres can survive the violent environs of a red dwarf star.

An international team of researchers has used NASA's James Webb Space Telescope to calculate the amount of heat energy coming from the rocky exoplanet TRAPPIST-1 c. The result suggests that the planet's atmosphere—if it exists at all—is extremely thin.

With a dayside temperature of roughly 380 Kelvin (about 225 degrees Fahrenheit), TRAPPIST-1 c is now the coolest rocky exoplanet ever characterized based on thermal emission. The precision necessary for these measurements further demonstrates Webb's utility in characterizing rocky exoplanets similar in size and temperature to those in our own solar system.

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New era of exoplanet discovery begins with images of 'Jupiter's younger sibling'
https://phys.org/news/2023-06-era-exopl ... piter.html
by W. M. Keck Observatory

Astronomers using W. M. Keck Observatory on Maunakea, Hawaiʻi Island have discovered one of the lowest-mass planets whose images have been directly captured. Not only were they able to measure its mass, but they were also able to determine that its orbit is similar to the giant planets in our own solar system.

The planet, called AF Lep b, is among the first ever discovered using a technique called astrometry; this method measures the subtle movements of a host star over many years to help astronomers determine whether hard-to-see orbiting companions, including planets, are gravitationally tugging at it.

The study, led by astronomy graduate student Kyle Franson at the University of Texas at Austin (UT Austin), is published in The Astrophysical Journal Letters.

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A Transiting Super-Earth in the Radius Valley and An Outer Planet Candidate Around HD 307842
https://arxiv.org/abs/2306.14655

Quote :

We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity (RV) measurements constrain the mass to be 9.67+0.83/-0.82 [Earth Masses]. We also report the discovery of an additional planet candidate on an outer orbit that is most likely non-transiting. The possible periods of the planet candidate are approximately 20 to 63 days, with the corresponding RV semi-amplitudes expected to range from 3.2 to 5.4 m/s and minimum masses from 12.6 to 31.1 [Earth Masses]. The radius of the transiting planet (planet b) is 1.93+0.11/-0.09 [Earth Radii], which results in a mean density of 7.4+1.4/-1.2 g/cm^3 suggesting that TOI-784b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784b is located at the lower edge of the so-called ``radius valley'' in the radius vs. insolation plane, which is consistent with the photoevaporation or core-powered mass loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are 88.60+0.84/-0.86 degrees and <= 88.3-89.2 degrees, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.

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Astronomers find a planet that shouldn't exist
https://phys.org/news/2023-06-astronome ... uldnt.html
by University of Hawaii at Manoa

When our sun reaches the end of its life, it will expand to 100 times its current size, enveloping the Earth. Many planets in other solar systems face a similar doom as their host stars grow old. But not all hope is lost, as astronomers from the University of Hawaiʻi Institute for Astronomy (UH IfA) have made the remarkable discovery of a planet's survival after what should have been certain demise at the hands of its sun.

The Jupiter-like planet 8 UMi b, officially named Halla, orbits the red giant star Baekdu (8 UMi) at only half the distance separating the Earth and the sun. Using two Maunakea Observatories on Hawaiʻi Island—W. M. Keck Observatory and Canada-France-Hawaiʻi Telescope (CFHT)—a team of astronomers led by Marc Hon, a NASA Hubble Fellow at UH IfA, has discovered that Halla persists despite the normally perilous evolution of Baekdu.

Using observations of Baekdu's stellar oscillations from NASA's Transiting Exoplanet Survey Satellite (TESS), they found that the star is burning helium in its core, signaling that it had already expanded enormously into a red giant star once before. The work is published in the journal Nature.

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The TESS-Keck Survey. XVI. Mass Measurements for 12 Planets in Eight Systems
https://arxiv.org/abs/2306.16587

Quote :

With JWST's successful deployment and unexpectedly high fuel reserves, measuring the masses of sub-Neptunes transiting bright, nearby stars will soon become the bottleneck for characterizing the atmospheres of small exoplanets via transmission spectroscopy. Using a carefully curated target list and more than two years' worth of APF-Levy and Keck-HIRES Doppler monitoring, the TESS-Keck Survey is working toward alleviating this pressure. Here we present mass measurements for 11 transiting planets in eight systems that are particularly suited to atmospheric follow-up with JWST. We also report the discovery and confirmation of a temperate super-Jovian-mass planet on a moderately eccentric orbit. The sample of eight host stars, which includes one subgiant, spans early-K to late-F spectral types (Teff= 5200--6200 K). We homogeneously derive planet parameters using a joint photometry and radial velocity modeling framework, discuss the planets' possible bulk compositions, and comment on their prospects for atmospheric characterization.

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KMT-2022-BLG-0475Lb and KMT-2022-BLG-1480Lb: Microlensing ice giants detected via non-caustic-crossing channel
https://arxiv.org/abs/2307.00753

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Two new sub-Neptunes orbiting nearby stars discovered with TESS
https://phys.org/news/2023-07-sub-neptu ... -tess.html

by Tomasz Nowakowski , Phys.org

An international team of astronomers reports the discovery of two new sub-Neptune exoplanets using NASA's Transiting Exoplanet Survey Satellite (TESS). The newfound alien worlds, designated TOI-2084 b and TOI-4184 b, orbit nearby M-dwarf stars and are about two and a half times larger than the Earth. The finding was detailed in a paper published June 26 on the preprint server arXiv.

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 nearly 6,700 candidate exoplanets (TESS Objects of Interest, or TOI), of which 360 have been confirmed so far.

Recently, a group of astronomers led by Khalid Barkaoui of the University of Liège in Belgium, has confirmed another two TOI exoplanet candidates. Using ground-based facilities, they conducted follow-up observations of two stars designated TOI-2084 and TOI-4184, finding that transit signals in their light curves are of planetary nature.