Demographics of Kepler Earth and Super Earth in the Habitable Zone

Comparing the occurrence rates of the habitable zone of Earth-size planets. Our result for a total of [0.56, 1.63] Sample M was plotted at full opacity, and lower opacity points indicate results from individual fits to five stellar mass bins with boundaries spanning {0.56, 0.81, 0.91, 1.01, 1.16, 1.63} meters (mass increasing from top to bottom). Circles indicate values ​​that assume that occurrence follows a functional form (our work, Bryson et al. 2021, 2020b; Neil & Rogers 2020; Pascucci et al. 2019; Zink et al. 2019; Garrett et al. 2018 and Mulders et al. 2018 ), and the boxes indicate values ​​from network-based incidence rates (Kunimoto & Matthews 2020; Hsu et al. 2019). Arrows pointing to the left indicate the upper boundary. The blue area represents works that directly study a core group of intrinsically rocky planets, the yellow area represents works that study reliability, and our work (shown in green) implements both considerations. The vertical gray line indicates the presence values ​​of ExoPAG SAG13 via Kopparapu et al. (2018) used in the final reports of the LUVOIR and HabEx missions. Similar plot for Γ⊕ estimates by Bryson et al. (2021) appears in Kunimoto & Matthews (2020) (Fig. 14).


Understanding the occurrence of Earth-sized planets in the habitable zone of Sun-like stars is essential to the search for analogues on Earth. However, the lack of reliable Kepler detections of such planets has forced many estimates to be derived from nearby populations (2

In this work, we calculate the intrinsic occurrence rates of the nearby super-Earths (∼1−2R⊕) and sub-Neptunes (∼2−3.5R⊕) of FGK stars (0.56−1.63M⊙) as a function of the orbital period and find evidence for two systems: where Super-Earths are more abundant at short orbital periods, and sub-Neptunes are more abundant at longer orbital periods. We fit a parametric model in five populated stellar mass bins and find that the orbital period of the transition between these two systems is of stellar mass, such as Ptrans M1.7 ± 0.2∗.

These results indicate the existence of a previous sub-Neptunian population that polluted the nearby super-Earth population of Gyr, indicative of a group formed by atmospheric loss. Using our model to constrain the population for long periods of intrinsically rocky planets, we estimate an incidence of Γ⊕ = 15 + 6−4% for Earth-size habitable zone planets, and predict that sub-Neptune ∼ will be twice as common as a super-Earth in the habitable zone (when normalized over the period of the orbital natural logarithm and the radius range used). Finally, we discuss our results in the context of future missions searching for habitable zone planets.

Galen J. Bergstein, Ilaria Pascucci, Jess de Mulders, and Rachel B.

Comments: 27 pages, 12 figures, 3 tables; Accepted for publication in AJ
Topics: Earth and Planetary Astrophysics (astro-ph.EP)
Cited as follows: arXiv: 2209.04047 [astro-ph.EP] (or arXiv: 2209.04047v1 [astro-ph.EP] for this version)
Submission date
WHO: Galen Bergstein
[v1] Thursday, September 8, 2022 22:07:54 UTC (6,043 KB)