Radial Velocity Survey of Low-Mass Companions to sdB Stars

TL;DR

This study uses high-resolution spectra to detect low-mass companions to sdB stars through radial velocity shifts, aiming to understand their formation and test theoretical models.

Contribution

It provides the first systematic search for substellar companions to sdB stars using precise radial velocity measurements.

Findings

No significant radial velocity variations detected.

Constraints placed on the population of low-mass companions.

Supports the hypothesis that substellar companions can influence sdB formation.

Abstract

The origin of subdwarf B (sdB) stars is not fully understood yet since it requires high mass loss at the red giant stage. SdBs in close binary systems are formed via common envelope ejection, but the origin of apparently single sdB stars remains unclear. Substellar companions may be able to trigger common envelope ejection and help forming sdBs that appear to be single. Using a sample of high resolution spectra we aim at detecting small radial velocity (RV) shifts caused by such low mass (sub-)stellar companions. The RVs are measured with high accuracy using sharp metal lines. Our goal is to test the theoretical predictions and put constraints on the population of the lowest mass companions to sdB stars.