Title of programme: The coolest small planet: Catching the transit of a small planet orbiting an M dwarf with P>100d and a precise mass from HARPS-N
Abstract: For smaller planets, precise bulk densities are crucial to understand their interior composition and to distinguish between a super-Earth or a sub-Neptune. This is essential input for understanding planet formation and evolution. With this proposal, we are asking for DDT CHEOPS time to detect and confirm the transit of only the second small planet with a precisely known mass orbiting its star with a period above 100 days. It would furthermore be the coldest (212) small planet around a bright star (G<13) ever. The host is an M2 dwarf with a well-characterised ultra-short period small planet. We found a dip in flux at the start of one of our CHEOPS GO data following up on this planet. By co-analysing the CHEOPS, TESS, and radial velocity data, we could rule out systematics and found the dip is consistent with a new small planet candidate orbiting the M dwarf beyond its habitable zone (P=101d). The only other known star with a well-characterised small planet at such orbits is nu2 Lupi (also done by CHEOPS). Confirming the transiting nature of our new planetary candidate would thus double the known small planets with precise densities on orbits beyond 100 days and be of great scientific interest.
Temporal Coverage
2022-12-18T19:13:54Z / 2022-12-20T12:12:00Z
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.
