2017/08/31 by Sivan Ginzburg, Hilke E. Schlichting, Re'em Sari +1 · 510 citations
Physics and Astronomy · #Accretion (finance) #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Exoplanet #Photoevaporation #Physics #Planet #Planetary mass #Planetary system #Population #Protoplanetary disk #RADIUS #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1093/mnras/sty290
published in Monthly Notices of the Royal Astronomical Society 476(1), 759-765 (Oxford University Press) · Matched to published version
openalex publication_date 2018/02/02 · arxiv created 2018/03/06 · arxiv updated 2018/03/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Recent observations identify a valley in the radius distribution of small exoplanets, with planets in the range 1.5–2.0 R⊕ significantly less common than somewhat smaller or larger planets. This valley may suggest a bimodal population of rocky planets that are either engulfed by massive gas envelopes that significantly enlarge their radius, or do not have detectable atmospheres at all. One explanation of such a bimodal distribution is atmospheric erosion by high-energy stellar photons. We investigate an alternative mechanism: the luminosity of the cooling rocky core, which can completely erode light envelopes while preserving heavy ones, produces a deficit of intermediate sized planets. We evolve planetary populations that are derived from observations using a simple analytical prescription, accounting self-consistently for envelope accretion, cooling and mass-loss, and demonstrate that core-powered mass-loss naturally reproduces the observed radius distribution, regardless of the high-energy incident flux. Observations of planets around different stellar types may distinguish between photoevaporation, which is powered by the high-energy tail of the stellar radiation, and core-powered mass-loss, which depends on the bolometric flux through the planet's equilibrium temperature that sets both its cooling and mass-loss rates.