{"work":{"id":"5a2b6391-a32e-4ebe-80af-ff07026815bf","openalex_id":"https://openalex.org/W2165134157","doi":"10.1088/0004-637x/775/2/105","arxiv_id":"1303.3899","raw_key":null,"title":"Kepler planets: a tale of evaporation","authors":[{"given":"James E.","family":"Owen","sequence":"first","affiliation":[]},{"given":"Yanqin","family":"Wu","sequence":"additional","affiliation":[]}],"authors_text":"Owen, J","year":2013,"venue":"astro-ph.EP","abstract":"(Abridged) Inspired by the Kepler planet discoveries, we consider the thermal contraction of planets close to their parent star, under the influence of evaporation. The mass-loss rates are based on hydrodynamic models of evaporation that include both X-ray and EUV irradiation. We find that only low-mass planets with hydrogen envelopes are significantly affected by evaporation, with evaporation being able to remove massive hydrogen envelopes inward of 0.1 AU for Neptune-mass objects.\n  We construct a theoretical population of planets with varying core masses, envelope masses, orbital separations, and stellar spectral types, and compare these against the sizes and densities measured for low-mass planets, both in the Kepler mission and from radial velocity surveys. This exercise leads us to conclude that evaporation is the driving force of evolution for close-in Kepler planets. In fact, some 50% of the Kepler planet candidates may have been significantly eroded. Evaporation explains two striking correlations observed in these objects: a lack of large radius/low density planets close to the stars, and a bimodal distribution in planet sizes with a deficit of planets around 2R_E. Planets that have experienced high X-ray exposures are generally smaller than this size, and those with lower X-ray exposures are typically larger. A bimodal distribution is naturally explained by the evaporation model, where, depending on their X-ray exposure, close-in planets can either hold on to hydrogen envelopes 1% in mass, or be stripped entirely.\n  To quantitatively reproduce the observed features, we argue that not only do low-mass Kepler planets need to be made of rocky cores overlaid with hydrogen envelopes, but few of them should have initial masses above 20 M_E, and the majority of them should have core masses of a few Earth masses.","external_url":"https://arxiv.org/abs/1303.3899","cited_by_count":766,"metadata_source":"pith","metadata_fetched_at":"2026-07-03T18:48:49.001138+00:00","pith_arxiv_id":"1303.3899","created_at":"2026-05-08T17:33:46.529432+00:00","updated_at":"2026-07-11T11:50:26.030339+00:00","title_quality_ok":true,"display_title":"Kepler planets: a tale of evaporation","render_title":"Kepler planets: a tale of evaporation"},"hub":{"state":{"work_id":"5a2b6391-a32e-4ebe-80af-ff07026815bf","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":25,"external_cited_by_count":766,"distinct_field_count":3,"first_pith_cited_at":"2026-01-29T08:05:19+00:00","last_pith_cited_at":"2026-07-02T00:30:37+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-08-06T14:09:57.003618+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":1}],"polarity_counts":[{"context_polarity":"background","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}