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Astronomers Create Catalog of Exotic Exoplanets

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Created as part of the TESS-Keck Survey, the new catalog includes 126 strange planets beyond our Solar System, from rare worlds with extreme environments to ones that could possibly support life as we know it.

An artist’s conception of 126 planets in the new TESS-Keck Survey catalog is based on data including planet radius, mass, density, and temperature; question marks represent planets requiring more data for full characterization. Image credit: W.M. Keck Observatory / Adam Makarenko.

“Relatively few of the previously known exoplanets have a measurement of both the mass and the radius,” said University of California, Riverside’s Professor Stephen Kane, principal investigator of the TESS-Keck Survey and co-author of a paper published in the Astrophysical Journal Supplement.

“The combination of these measurements tells us what the planets could be made of and how they formed.”

“With this information, we can begin to answer questions about where our Solar System fits in to the grand tapestry of other planetary systems.”

Professor Kane and his colleagues analyzed more than 13,000 radial velocity (RV) measurements to calculate the masses of 120 confirmed planets, plus six candidate planets, spread out over the northern sky.

“These RV measurements let astronomers detect and learn the properties of these exoplanetary systems,” said University of Kansas astrophysicist Ian Crossfield.

“When we see a star wobbling regularly back and forth, we can infer the presence of an orbiting planet and measure the planet’s mass.”

Several planets in the TESS-Keck Survey stand out as touchstones for deepening astronomers’ understanding of the diverse ways planets form and evolve.

In a related paper in the Astronomical Journal, the astronomers announced the discovery of two new planets orbiting a solar-type star.

The first is a sub-Saturn planet with a mass and radius that are between those of Neptune and Saturn.

“There is ongoing debate about whether sub-Saturn planets are truly rare, or if we are just bad at finding planets like these,” said University of California, Riverside graduate student Michelle Hill.

“So, this planet, TOI-1386b, is an important addition to this demographic of planets.”

TOI-1386b only takes 26 days to orbit its star. Meanwhile its neighbor, a planet with a mass close to that of Saturn, takes 227-days to orbit the same star.

In another related paper, the researchers described TOI-1437b, a planet about half the size of Neptune that takes a mere 19 days to orbit its star, which is much like our Sun.

“Planets smaller than Neptune but larger than Earth are the most prevalent worlds in our galaxy, yet they are absent from our own Solar System,” said University of California, Riverside graduate student Daria Pidhorodetska.

“Each time a new one is discovered, we are reminded of how diverse our Universe is, and that our existence in the cosmos may be more unique than we can understand.”

Planets with extreme, ultra-short orbits around stars unlike our Sun are also detailed in the catalog.

One is so close to its orange dwarf star it completes orbit in less than 12 hours.

“TOI-1798c orbits its star so quickly that one year on this planet lasts less than half a day on Earth,” said University of Kansas graduate student Alex Polanski.

“Because of their proximity to their host stars, planets like this one are also ultra hot — receiving more than 3,000 times the radiation that Earth receives from the Sun.”

“Existing in this extreme environment means that this planet has likely lost any atmosphere that it initially formed.”

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Alex S. Polanski et al. 2024. The TESS-Keck Survey. XX. 15 New TESS Planets and a Uniform RV Analysis of All Survey Targets. ApJS 272, 32; doi: 10.3847/1538-4365/ad4484

Michelle L. Hill et al. 2024. The TESS-Keck Survey. XIX. A Warm Transiting Sub-Saturn-mass Planet and a Nontransiting Saturn-mass Planet Orbiting a Solar Analog. AJ 167, 151; doi: 10.3847/1538-3881/ad2765

Daria Pidhorodetska et al. 2024. The TESS-Keck Survey. XXII. A sub-Neptune Orbiting TOI-1437. arXiv: 2405.12448

Source : Breaking Science News

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