Exclusion of Stellar Companions to Exoplanet Host Stars

TL;DR

This systematic speckle imaging survey of 71 exoplanet host stars found that most lack stellar companions down to certain luminosity and separation limits, informing future radial velocity studies.

Contribution

The paper provides the first large-scale speckle imaging results for exoplanet hosts, setting detection limits and aiding interpretation of companion signals.

Findings

Most stars have no detectable stellar companions.

Detection limits constrain possible companion masses.

Results inform future radial velocity follow-up.

Abstract

Given the frequency of stellar multiplicity in the solar neighborhood, it is important to study the impacts this can have on exoplanet properties and orbital dynamics. There have been numerous imaging survey projects established to detect possible low-mass stellar companions to exoplanet host stars. Here we provide the results from a systematic speckle imaging survey of known exoplanet host stars. In total, 71 stars were observed at 692~nm and 880~nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. Our results show that all but 2 of the stars included in this sample have no evidence of stellar companions with luminosities down to the detection and projected separation limits of our instrumentation. The mass-luminosity relationship is used to estimate the maximum mass a stellar companion can have without being detected. These results are used to discuss the potential for further radial velocity follow-up and interpretation of companion signals.