The Impact of Stripped Cores on the Frequency of Earth-size Planets in the Habitable Zone

Ilaria Pascucci, Gijs D. Mulders, Eric Lopez

Research output: Contribution to journalArticle

Abstract

The frequency of Earth-size planets in the habitable zone (HZ) of Sun-like stars, hereafter η , is a key parameter to evaluate the yield of nearby Earth analogs that can be detected and characterized by future missions. Yet, this value is poorly constrained as there are no reliable exoplanet candidates in the HZ of Sun-like stars in the Kepler field. Here, we show that extrapolations relying on the population of small (<1.8 R ), short-period (<25 days) planets bias η to large values. As the radius distribution at short orbital periods is strongly affected by atmospheric loss, we reevaluate η using exoplanets at larger separations. We find that η drops considerably, to values of only ∼5%-10%. Observations of young (<100 Myr) clusters can probe short-period sub-Neptunes that still retain most of their envelope mass. As such, they can be used to quantify the contamination of sub-Neptunes to the population of Kepler short-period small planets and aid in more reliable estimates of η .

Original languageEnglish (US)
Article numberL15
JournalAstrophysical Journal Letters
Volume883
Issue number1
DOIs
StatePublished - Sep 20 2019

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planets
Neptune (planet)
planet
Neptune
extrasolar planets
sun
Earth analogs
stars
aid
extrapolation
contamination
envelopes
probe
orbitals
radii
probes
estimates
loss
distribution
young

Keywords

  • methods: data analysis
  • planets and satellites: detection
  • planets and satellites: terrestrial planets
  • surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The Impact of Stripped Cores on the Frequency of Earth-size Planets in the Habitable Zone. / Pascucci, Ilaria; Mulders, Gijs D.; Lopez, Eric.

In: Astrophysical Journal Letters, Vol. 883, No. 1, L15, 20.09.2019.

Research output: Contribution to journalArticle

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abstract = "The frequency of Earth-size planets in the habitable zone (HZ) of Sun-like stars, hereafter η ⊕, is a key parameter to evaluate the yield of nearby Earth analogs that can be detected and characterized by future missions. Yet, this value is poorly constrained as there are no reliable exoplanet candidates in the HZ of Sun-like stars in the Kepler field. Here, we show that extrapolations relying on the population of small (<1.8 R ⊕), short-period (<25 days) planets bias η ⊕ to large values. As the radius distribution at short orbital periods is strongly affected by atmospheric loss, we reevaluate η ⊕ using exoplanets at larger separations. We find that η ⊕ drops considerably, to values of only ∼5{\%}-10{\%}. Observations of young (<100 Myr) clusters can probe short-period sub-Neptunes that still retain most of their envelope mass. As such, they can be used to quantify the contamination of sub-Neptunes to the population of Kepler short-period small planets and aid in more reliable estimates of η ⊕.",
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