The Impact of Stripped Cores On The Frequency Of Earth-size Planets In The Habitable Zone


DR25+Gaia candidate list, color coded by survey completeness. The sample includes only dwarfs and planet candidates with a Robovetter score ≥ 0.9. The grey rectangle delineates the HZ, no reliable planet candidate is detected inside the HZ. Occurrence rates using the inverse detection efficiency method are also provided for nine period and two radius bins (black rectangles).

The frequency of Earth-size planets in the habitable zone of Sun-like stars, hereafter η⊕, is a key parameter to evaluate the yield of nearby Earth analogues that can be detected and characterized by future missions.

Yet, this value is poorly constrained as there are no reliable exoplanet candidates in the habitable zone of Sun-like stars in the Kepler field. Here, we show that extrapolations relying on the population of small (<1.8R⊕) short-period (<25days) planets bias η⊕ to large values. As the radius distribution at short orbital periods is strongly affected by atmospheric loss, we re-evaluate 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⊕.

I. Pascucci, G. Mulders, E. Lopez
(Submitted on 16 Aug 2019)

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1908.06192 [astro-ph.EP] (or arXiv:1908.06192v1 [astro-ph.EP] for this version)
Submission history
From: Ilaria Pascucci
[v1] Fri, 16 Aug 2019 22:09:00 UTC (1,107 KB)
https://arxiv.org/abs/1908.06192
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