Title of programme: The most precise radius and mass determination of an exoearth
Abstract: Gl 486 b is a transiting rocky planet in a 1.47 d orbital period around a relatively bright M3.5 V low-mass star at only 8.08 pc. Using TESS, CARMENES and MAROON-X, Trifonov et al. (subm. to Science) measured precise planet mass and radius of 2.82 M_Terra and 1.605 R_Terra with relative uncertainties of 4.2% and 5.1%, respectively. We aim to improve the Gl 486 bs mass and radius determination down to 2-3% with additional precise RV data and, crucially, photometric follow-up by CHEOPS. Such a precision in the planet mass and radius would give rise to rocky planet internal composition and structure studies not done before (e.g. constraining the core-to-mantle ratio with an accuracy better than 10%, investigating the planets oxygen fugacity). Because of its equilibrium temperature, below the molten lava temperature boundary but high enough for having the largest emission and transmission spectroscopic metrics among M-dwarf transiting rocky planets, and the relative brightness and weak activity of its stellar host, Gl 486 b is also ideal for atmospheric investigation. A better mass and, especially, radius determination can constrain theories for how terrestrial planets around M dwarfs form and retain atmospheres. We request observing 10 transits in 10 visits of 2 orbits each (total requested time: 20 orbits).
Temporal Coverage
2021-05-26T08:57:00Z / 2021-05-26T17:18:00Z
Version
3.0
Mission Description
CHEOPS (Benz et al., https://doi.org/10.1007/s10686-020-09679-4) is a European Space Agency (ESA) mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the United Kingdom.
The satellite has a single payload comprising an ultra-high precision photometer covering the 330 - 1100 nm wavelength range in a single photometric band. Observations are made as part of the Guaranteed Time Observing Programme that is formulated by the CHEOPS Science Team, and the Guest Observers Programme through which the Community at large can apply for CHEOPS time.
