About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of their Intrinsic Architecture
Wei Zhu (CITA), Cristobal Petrovich, Yanqin Wu, Subo Dong, Jiwei Xie
(Submitted on 26 Feb 2018)
We constrain the intrinsic architecture of Kepler planetary systems by modeling the observed multiplicities of the
transiting planets (tranets) and their transit timing variations (TTVs). We robustly determine that the fraction
of Sun-like stars with Kepler -like planets, ηKepler, is 30 ± 3%. Here Kepler -like planets are planets that have radii
Rp & R⊕ and orbital periods P < 400 days. Our result thus significantly revises previous claims that more than 50%
of Sun-like stars have such planets. Combining with the average number of Kepler planets per star (∼ 0.9), we obtain
that on average each planetary system has 3.0±0.3 planets within 400 days. We also find that the dispersion in orbital
inclinations of planets within a given planetary system, σi,k, is a steep function of its number of planets, k. This can
be parameterized as σi,k ∝ kα and we find that −4 < α < −2 at 2-σ level. Such a distribution well describes the
observed multiplicities of both tranets and TTVs with no excess of single tranets. Therefore we do not find evidence
supporting the so-called “Kepler dichotomy.” Together with a previous study on orbital eccentricities, we now have
a consistent picture: the fewer planets in a system, the hotter it is dynamically. We discuss briefly possible scenarios
that lead to such a trend. Despite our Solar system not belonging to the Kepler club, it is interesting to notice that
the Solar system also has three planets within 400 days and that the inclination dispersion is similar to Kepler systems
of the same multiplicity.
Comments: 19 pages, 12 figures, submitted to AAS Journals, comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1802.09526 [astro-ph.EP]
(or arXiv:1802.09526v1 [astro-ph.EP] for this version)
Submission history
From: Wei Zhu
[v1] Mon, 26 Feb 2018 19:00:00 GMT (231kb,D)
https://arxiv.org/abs/1802.09526
