Using data from NASAs Kepler\/K2 mission and several ground-based instruments, astronomers have discovered a planetary system with three transiting planets around the 9-billion-year-old star EPIC 249893012.<\/p>\n
An artists impression of the EPIC 249893012 planetary system. Image credit: Sci-News.com.<\/p>\n
EPIC 249893012 is a G8-type evolved star located approximately 1,057 light-years away from Earth.<\/p>\n
Also known as 2MASS J15125956-1643282 or TYC 6170-95-1, the star is 71% larger than the Sun, but has a mass of just 1.05 times solar.<\/p>\n
EPIC 249893012, which is approximately 9 billion years old, hosts at least three massive planets.<\/p>\n
The inner planet is a hot super-Earth with an orbital period of 3.6 days.<\/p>\n
Named EPIC 249893012b, the alien world is 1.95 times bigger than Earth and 8.75 times more massive.<\/p>\n
EPIC 249893012b is a super-Earth with a density compatible with a pure silicate composition. However, a more realistic configuration would be a nickel-iron core and a silicate mantle, said Diego Hidalgo from the Instituto de Astrofisica de Canarias and the Universidad de La Laguna, Tenerife, and his colleagues.<\/p>\n
The planet has some residual hydrogen-helium atmosphere, which enlarges its radius but does not significantly contribute to the total planet mass.<\/p>\n
Planets EPIC 249893012c and d are warm sub-Neptunes with orbital periods of 15.6 and 35.7 days, respectively.<\/p>\n
They have masses and radii of 14.67 Earth masses and 3.67 Earth radii and 10.2 Earth masses and 3.94 Earth radii.<\/p>\n
The three new planets were first discovered in data from the Kepler\/K2 mission.<\/p>\n
Hidalgo and co-authors then confirmed the discovery using the InfraRed Camera and Spectrograph (IRCS) on the 8.2-m Subaru Telescope, the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph at the 3.6-m telescope of ESOs La Silla Observatory, and the HARPS-N spectrograph at the 3.58-m Telescopio Nazionale Galileo at Roque de Los Muchachos Observatory.<\/p>\n
Combining K2 photometry with high-resolution imaging and high-precision Doppler spectroscopy, we confirmed the three planets and determined their masses, radii, and mean densities, the astronomers explained.<\/p>\n
Because the EPIC 249893012 system is at an early stage of its evolution after leaving the main sequence, it is a good candidate for a detailed study of its dynamical evolution to (i) shed light on the formation of close-in giant planets, and (ii) test a hypothesis that giant planets form a dynamical barrier that confines super-Earths to an inward-migrating evolution, they said.<\/p>\n
The teams paper was published in the journal Astronomy & Astrophysics (arXiv.org preprint).<\/p>\n
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D. Hidalgo et al. 2020. Three planets transiting the evolved star EPIC 249893012: a hot 8.8-MEarth super-Earth and two warm 14.7 and 10.2-MEarth sub-Neptunes. A&A, in press; doi: 10.1051\/0004-6361\/201937080<\/p>\n
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Astronomers Find Three Massive Exoplanets Orbiting Evolved Star | Astronomy - Sci-News.com<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Using data from NASAs Kepler\/K2 mission and several ground-based instruments, astronomers have discovered a planetary system with three transiting planets around the 9-billion-year-old star EPIC 249893012. An artists impression of the EPIC 249893012 planetary system. Image credit: Sci-News.com. Continue reading