Two Terrestrial Planet Families with Different Origins

Author(s)

Swain, Mark R. ^[1] ; Estrela, Raissa ^{[1, 2]} ; Sotin, Christophe ^[1] ; Roudier, Gael M. ^[1] ; Zellem, Robert T. ^[1]

Affiliation

^[1] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 - USA

^[2] Univ Prebiteriana Mackenzie, CRAAM, Rua Consolacao 896, Sao Paulo - Brazil

• Document type: Journal article
• Source: ASTROPHYSICAL JOURNAL; v. 881, n. 2 AUG 20 2019.
• Web of Science Citations: 0

Abstract

The potentially important role of stellar irradiation in envelope removal for planets with diameters of less than or similar to 2 R-circle plus has been inferred both through theoretical work and the observed bimodal distribution of small planet occurrence as a function of radius. We examined the trends for small planets in the three-dimensional radius-insolation-density space and found that the terrestrial planets divide into two distinct families based on insolation. The lower insolation family merges with terrestrial planets and small bodies in the solar system and is thus Earth-like. The higher insolation terrestrial planet family forms a bulk-density continuum with the sub-Neptunes, and is thus likely to be composed of remnant cores produced by photoevaporation. Based on the density-radius relationships, we suggest that both terrestrial families show evidence of density enhancement through collisions. Our findings highlight the important role that both photoevaporation and collisions have in determining the density of small planets. (AU)

• FAPESP's process: 18/09984-7 - Unveiling haze formation and energy balance in the exoplanets atmospheres with the Hubble Space Telescope
• Grantee: Raissa de Lourdes Freitas Estrela
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate