Atmospheric Evolution and Loss of a Recently Discovered Low-Density Ultra-Short Period Super-Earth

Redfield, Seth; Bluhm, Paz; Carleo, Ilaria; Casasayas Barris, Nuria; Palle, Enric; Vidotto, Aline; Villarreal D'Angelo, Carolina
Bibliographical reference

HST Proposal

Advertised on:
6
2021
Number of authors
7
IAC number of authors
1
Citations
0
Refereed citations
0
Description
Super-Earth characterization continues to be a particular focus of the field given that it is the interface between terrestrial planets and gas-dominated planets. The implications of this division reverberate in planet formation, planetary interiors, and the origins and evolution of planetary atmospheres. A recently discovered ultra-short period exoplanet, TOI-1685b, is the lowest density super-Earth to orbit a small, low-mass star. Its low density and small host star, make it an ideal candidate for extended atmosphere characterization and a measurement of super-Earth mass loss. TOI-1685b has a relatively hot atmosphere, which makes it an excellent target for measuring atmospheric hydrogen escape, particularly given its close orbit, deep within the stellar wind of its host star. Measurements of hydrogen escape provides constraints on the evolution of the planetary atmosphere. We propose spectroscopic observations of two planetary transits to measure the stellar Lyman-alpha emission line and search for signatures of an extended hydrogen atmosphere. The Lyman-alpha line is also the dominant source of UV emission for cool stars, and thereby has a tremendous impact on planetary atmospheres. These observations, along with a short near-UV observation of MgII, the second most dominant emission line, will provide a vital characterization of the stellar inputs into all of the planetary atmospheres in this system. Observations of hot and largely cloud-free atmospheres, particularly of super-Earths like the one requested in this proposal, are an important step in planning future observations of temperate planetary atmospheres.