UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Three planets transiting the evolved star EPIC 249893012: A hot 8.8-M⊕ super-Earth and two warm 14.7 and 10.2-M⊕ sub-Neptunes

Hidalgo, D; Pallé, E; Alonso, R; Alonso, R; Gandolfi, D; Nowak, G; Luque, R; ... Wilson, PA; + view all (2020) Three planets transiting the evolved star EPIC 249893012: A hot 8.8-M⊕ super-Earth and two warm 14.7 and 10.2-M⊕ sub-Neptunes. Astronomy and Astrophysics , 636 , Article A98. 10.1051/0004-6361/201937080. Green open access

[thumbnail of Van Eylen_Three planets transiting the evolved star EPIC 249893012_VoR.pdf]
Preview
Text
Van Eylen_Three planets transiting the evolved star EPIC 249893012_VoR.pdf - Published Version

Download (1MB) | Preview

Abstract

We report the discovery of a new planetary system with three transiting planets, one super-Earth and two sub-Neptunes, that orbit EPIC 249893012, a G8 IV-V evolved star (M? = 1.05 ± 0.05 M�, R? = 1.71 ± 0.04 R�, Teff = 5430 ± 85 K). The star is just leaving the main sequence. We combined K2 photometry with IRCS adaptive-optics imaging and HARPS, HARPS-N, and CARMENES highprecision radial velocity measurements to confirm the planetary system, determine the stellar parameters, and measure radii, masses, and densities of the three planets. With an orbital period of 3.5949+0.0007 −0.0007 days, a mass of 8.75+1.09 −1.08 M⊕, and a radius of 1.95+0.09 −0.08 R⊕, the inner planet b is compatible with nickel-iron core and a silicate mantle (ρb = 6.39+1.19 −1.04 g cm−3 ). Planets c and d with orbital periods of 15.624+0.001 −0.001 and 35.747+0.005 −0.005 days, respectively, have masses and radii of 14.67+1,84 −1.89 M⊕ and 3.67+0.17 −0.14 R⊕ and 10.18+2.46 −2.42 M⊕ and 3.94+0.13 −0.12 R⊕, respectively, yielding a mean density of 1.62+0.30 −0.29 and 0.91+0.25 −0.23 g cm−3 , respectively. The radius of planet b lies in the transition region between rocky and gaseous planets, but its density is consistent with a rocky composition. Its semimajor axis and the corresponding photoevaporation levels to which the planet has been exposed might explain its measured density today. In contrast, the densities and semimajor axes of planets c and d suggest a very thick atmosphere. The singularity of this system, which orbits a slightly evolved star that is just leaving the main sequence, makes it a good candidate for a deeper study from a dynamical point of view.

Type: Article
Title: Three planets transiting the evolved star EPIC 249893012: A hot 8.8-M⊕ super-Earth and two warm 14.7 and 10.2-M⊕ sub-Neptunes
Open access status: An open access version is available from UCL Discovery
DOI: 10.1051/0004-6361/201937080
Publisher version: https://doi.org/10.1051/0004-6361/201937080
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: planetary systems – planets and satellites: detection – techniques: photometric – techniques: radial velocities – planets and satellites: fundamental parameters
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10103472
Downloads since deposit
83Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item