Influence of Stellar Multiplicity On Planet Formation. IV. Adaptive Optics Imaging of Kepler Stars With Multiple Transiting Planet Candidates

TL;DR

This study investigates how stellar companions affect the formation of multi-planet systems detected by Kepler, finding a lower rate of close stellar companions around these systems compared to field stars, implying possible suppression or disruption effects.

Contribution

It provides the first comprehensive measurement of stellar multiplicity rates for Kepler multi-planet systems using adaptive optics imaging, revealing a significant deficit of close stellar companions.

Findings

Lower multiplicity rate (5.2%) for close companions (1-100 AU) around MTPS.

No significant difference in multiplicity rates at wider separations (100-2000 AU).

Suggests stellar companions may suppress planet formation or disrupt orbital coplanarity.

Abstract

The Kepler mission provides a wealth of multiple transiting planet systems (MTPS). The formation and evolution of multi-planet systems are likely to be influenced by companion stars given the abundance of multi stellar systems. We study the influence of stellar companions by measuring the stellar multiplicity rate of MTPS. We select 138 bright (KP < 13.5) Kepler MTPS and search for stellar companions with AO imaging data and archival radial velocity (RV) data. We obtain new AO images for 73 MTPS. Other MTPS in the sample have archival AO imaging data from the Kepler Community Follow-up Observation Program (CFOP). From these imaging data, we detect 42 stellar companions around 35 host stars. For stellar separation 1 AU < a < 100 AU, the stellar multiplicity rate is 5.2 $\pm$ 5.0% for MTPS, which is 2.8{\sigma} lower than 21.1 $\pm$ 2.8% for the control sample, i.e., the field stars in the solar neighborhood. We identify two origins for the deficit of stellar companions within 100 AU to MTPS: (1) a suppressive planet formation, and (2) the disruption of orbital coplanarity due to stellar companions. To distinguish between the two origins, we compare the stellar multiplicity rates of MTPS and single transiting planet systems (STPS). However, current data are not sufficient for this purpose. For 100 AU < a < 2000 AU, the stellar multiplicity rates are comparable for MTPS (8.0 $\pm$ 4.0%), STPS (6.4 $\pm$ 5.8%), and the control sample (12.5 $\pm$ 2.8%).