Occurrence and Architecture of Kepler Planetary Systems as Functions of Stellar Mass and Effective Temperature

Abstract

The Kepler mission has discovered thousands of exoplanets around various stars with different spectral types (M, K, G, and F) and thus different masses and effective temperatures. Previous studies have shown that the planet occurrence rate, in terms of the average number of planets per star, drops with increasing stellar effective temperature (T eff ). In this paper, with the final Kepler Data Release (DR25) catalog, we revisit the relation between stellar effective temperature (as well as mass) and planet occurrence, but in terms of the fraction of stars with planets and the number of planets per planetary system (i.e., planet multiplicity). We find that both the fraction of stars with planets and planet multiplicity decrease with increasing stellar temperature and mass. Specifically, about 75% late-type stars (T eff < 5000 K) have Kepler -like planets with an average planet multiplicity of ∼2.8, while for early-type stars (T eff > 6500 K), this fraction and the average multiplicity fall down to ∼35% and ∼1.8, respectively. The decreasing trend in the fraction of stars with planets is very significant with ∆AIC> 30, though the trend in planet multiplicity is somewhat tentative with ∆AIC∼ 5. Our results also allow us to derive the dispersion of planetary orbital inclinations in relationship with stellar effective temperature. Interestingly, it is found to be similar to the well-known trend between obliquity and stellar temperature, indicating that the two trends might have a common origin.

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

“…Introduction A primary aim of exoplanetary science is to use the observed properties of planetary systems to constrain theoretical models of planet formation (which occurs in the protoplanetary disk) and evolution (which occurs after disk dispersal). This problem is approached in a number of ways: by forward modeling of the formation and evolution processes and comparison between simulated and observed exoplanet populations ("planet population synthesis"; e.g., Mordasini et al 2009); through measuring the dependence of planet occurrence rates on fundamental stellar properties such as mass (e.g., Howard et al 2012;Yang et al 2020), metallicity (e.g., Fischer & Valenti 2005;Petigura et al 2018), or multiplicity (e.g., Wang et al 2014aWang et al , 2014b; and via case studies of individual systems that challenge conventional wisdom about the planet formation process (e.g., Carter et al 2012;Lopez & Fortney 2013).…”

SWEET-Cat 2.0: The Cat just got SWEETer

“…The relation between the occurrence rate of planets and stellar mass is a statistical result from exoplanetary surveys that enriches our understanding of planet formation (e.g., Fulton & Petigura 2018;Lozovsky et al 2021;Neil & Rogers 2018;Yang et al 2020). Because SWEET-Cat is a catalog of host stars only, it is impossible to estimate the occurrence rates of planets and their dependence on stellar parameters.…”

California-Kepler Survey. IX. Revisiting the Minimum-mass Extrasolar Nebula with Precise Stellar Parameters

“…19. Yang et al (2020) analyzed in conjunction the occurrence and architecture (multiplicity and mutual inclination) of Kepler planets following the methods of Zhu et al (2016). They found that for late-K, early-M stars (<4000K) the fraction of stars hosting sub-Neptune planets is ∼55% with a typical intrinsic multi-plicity of 3 planets, whereas the numbers drops steadily to early-type stars (∼15% F stars host Kepler-like systems with a multiplicity of ∼2).…”