Exoplanet Orbital Distribution around FGK Sun-like Host Stars I: planet occurrence rate derived from the Kepler Mission and theoretical interpretations from planet formation
Li Zeng, Stephanie C. Werner, Stein B. Jacobsen, Elena Mamonova, Reidar G. Trønnes + 1 more
TLDR
This paper analyzes Kepler data to reveal a log-uniform orbital distribution for most exoplanets around Sun-like stars, informing formation theories.
Key contributions
- Used survival function analysis on Kepler data to study exoplanet orbital distributions.
- Elucidated orbital distributions (period P or semi-major axis a) for exoplanets.
- Discovered a log-uniform orbital distribution for most exoplanets, excluding giants.
- Explored theoretical formation scenarios to explain observed orbital distributions.
Why it matters
This paper provides crucial statistical insights into exoplanet orbital distributions around Sun-like stars. The discovery of a log-uniform distribution for most planets offers new constraints for theoretical models of planet formation, advancing our understanding of how planetary systems evolve.
Original Abstract
Recent astronomical observations, in particular from the Kepler and TESS missions and their related follow-ups, have revealed an abundance of exoplanets in the size range between Neptune (4 Earth radii) and Earth (1 Earth radii ), as well as a low occurrence rate of planets around twice the radius of Earth (2 Earth radii). This paper uses statistical methods, in particular, the survival function analysis, to address the known exoplanet population observed mainly from the Kepler's primary mission, in order to mathematically elucidate the orbital distributions (expressed in either the orbital period P or the orbital semi-major axis a), for each of the host stars, in both a collective way, and also separately for the planets grouped into various radius bins. We uncover a log-uniform distribution for the majority of planets except the giants. Based on the results of the statistics, we then visit several possible formation scenarios and pathways for planets in different size ranges, in order to explain the results from a theoretical point-of-view.
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