WASP-107b is a super-Neptuneexoplanet that orbits the star WASP-107. It lies 200 light-years away from Earth in the constellation Virgo.[3] Its discovery was announced in 2017 by a team led by D. R. Anderson via the WASP-South.[4]
Planetary orbit
WASP-107b could not have formed in its current orbit. It likely migrated inward from its birth orbit beyond 1 AU due to interaction with the heavier planet WASP-107c. It is in a retrograde orbit, strongly misaligned with the equatorial plane of the parent star. The misalignment angle is equal to 118°+38 −19.[5] WASP-107c follows a highly eccentric and inclined orbit with a period of 1088+15 −16days.[2]
Physical characteristics
WASP-107b is a super-Neptuneice giantexoplanet roughly the size of Jupiter but less than one-tenth of Jupiter's mass, making it one of known lowest density-exoplanets.[2] This is unusual provided that the mean temperature of its upper atmosphere is only
500 °C (932 °F), much lower than that of similarly inflated exoplanets.[6] Its highly extended and low density atmosphere coupled with transiting a moderately bright orange dwarf star makes it an attractive target for atmospheric characterization via transmission spectroscopy.[7] It is about eight times nearer to its star than Mercury is to the Sun and orbits its star every 5.7 days.[3]
Helium was discovered in the planet's atmosphere in 2018, making it the first time helium was discovered on an exoplanet.[8] A follow-up observation with Keck in 2020 showed that the helium absorption extends beyond transit-egress.[9]Extreme ultraviolet radiation from the host star is gradually whittling down the planet's atmosphere, forming a comet-like tail 7 times as long as the radius of the planet.[10][11]
In November 2023, scientists discovered that its atmosphere contains water (H2O) vapour and sulfur dioxide (SO2). The clouds on this planet are made up of silicates.[12][13] The data, along with the unexpectedly low abundance of methane (CH4), suggests a hotter interior and a more massive core than previously estimated. Tidal heating, caused by the planet's slightly elliptical orbit, is believed to be the source of the extra internal heat.[14]
In September 2024 it was revealed that there is an east-west asymmetry in the atmospheric properties (e.g, climate, cloud structure) of WASP-107b, which previously had not been expected for planet of its kind.[6]
^Rubenzahl, Ryan A.; Dai, Fei; Howard, Andrew W.; Chontos, Ashley; Giacalone, Steven; Lubin, Jack; Rosenthal, Lee J.; Isaacson, Howard; Batalha, Natalie M.; Crossfield, Ian J. M.; Dressing, Courtney; Fulton, Benjamin; Huber, Daniel; Kane, Stephen R.; Petigura, Erik A.; Robertson, Paul; Roy, Arpita; Weiss, Lauren M.; Beard, Corey; Hill, Michelle L.; Mayo, Andrew; Mocnik, Teo; Murphy, Joseph M. Akana; Scarsdale, Nicholas (2021), "The TESS–Keck Survey. IV. A Retrograde, Polar Orbit for the Ultra-low-density, Hot Super-Neptune WASP-107b", The Astronomical Journal, 161 (3): 119, arXiv:2101.09371, Bibcode:2021AJ....161..119R, doi:10.3847/1538-3881/abd177, S2CID231698426
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