Statistical Time-Resolved Spectroscopy: A higher fraction of short-period binaries for metal-rich F-type dwarfs in SDSS

TL;DR

This study uses time-resolved spectroscopy from SDSS to analyze the binary fraction of F-type dwarfs in the Milky Way, revealing a higher prevalence of short-period binaries among metal-rich disk stars compared to metal-poor halo stars.

Contribution

It introduces a statistical method to measure short-period binary fractions in field stars using archived spectroscopic data, highlighting differences based on stellar metallicity.

Findings

Metal-rich disk stars are 30% more likely to have short-period binaries than metal-poor halo stars.

The analysis constrains the binary fraction for periods shorter than 12 days.

Time-resolved spectroscopy can effectively reveal stellar multiplicity in large surveys.

Abstract

Stellar multiplicity lies at the heart of many problems in modern astrophysics, including the physics of star formation, the observational properties of unresolved stellar populations, and the rates of interacting binaries such as cataclysmic variables, X-ray binaries, and Type Ia supernovae. However, little is known about the stellar multiplicity of field stars in the Milky Way, in particular about the differences in the multiplicity characteristics between metal-rich disk stars and metal-poor halo stars. In this study we perform a statistical analysis of ~14,000 F-type dwarf stars in the Milky Way through time-resolved spectroscopy with the sub-exposures archived in the Sloan Digital Sky Survey. We obtain absolute radial velocity measurements through template cross-correlation of individual sub-exposures with temporal baselines varying from minutes to years. These sparsely sampled radial velocity curves are analyzed using Markov chain Monte Carlo techniques to constrain the very short-period binary fraction for field F-type stars in the Milky Way. Metal-rich disk stars were found to be 30% more likely to have companions with periods shorter than 12 days than metal-poor halo stars.