About 30% of Sunlike Stars Have Keplerlike Planetary Systems: A Study of Their Intrinsic Architecture
Abstract
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 Sunlike stars with Keplerlike planets, η _{Kepler}, is 30 ± 3%. Here, Keplerlike planets are planets that have radii R _{p} ≳ R _{⊕} and orbital periods P < 400 days. Our result thus significantly revises previous claims that more than 50% of Sunlike stars have such planets. Combined 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, σ _{ i,k }, is a steep function of its number of planets, k. This can be parameterized as {σ }_{i,k}\propto {k}^{α } and we find that 4 < α < 2 at the 2σ level. Such a distribution well describes the observed multiplicities of both transits and TTVs with no excess of singletranet systems. Therefore we do not find evidence supporting the socalled “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.
 Publication:

The Astrophysical Journal
 Pub Date:
 June 2018
 DOI:
 10.3847/15384357/aac6d5
 arXiv:
 arXiv:1802.09526
 Bibcode:
 2018ApJ...860..101Z
 Keywords:

 methods: statistical;
 planetary systems;
 planets and satellites: general;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 20 pages, 12 figures, 1 table