A search for runaway stars in twelve Galactic supernova remnants

TL;DR

This study searches for runaway stars of all spectral types in twelve Galactic supernova remnants using Gaia data and spectroscopic analysis, aiming to identify ejected companions and constrain supernova models.

Contribution

It is the first comprehensive search for runaway stars across all spectral types in multiple supernova remnants, utilizing Gaia data and spectroscopic lithium tests.

Findings

Identified six dwarf stars with significant lithium, indicating youth.

Provided spectral analysis including radial velocities and atmospheric parameters.

Presented constraints on the number of ejected runaway stars versus models.

Abstract

Runaway stars can result from core-collapse supernovae in multiple stellar systems. If the supernova disrupts the system, the companion gets ejected with its former orbital velocity. A clear identification of a runaway star can yield the time and place of the explosion as well as orbital parameters of the pre-supernova binary system. Previous searches have mostly considered O- and B-type stars as runaway stars because they are always young in absolute terms (not much older than the lifetime of the progenitor) and can be detected up to larger distances. We present here a search for runaway stars of all spectral types. For late-type stars, a young age can be inferred from the lithium test. We used Gaia data to identify and characterise runaway star candidates in nearby supernova remnants, obtained spectra of 39 stars with UVES at the VLT and HDS at the Subaru telescope and found a significant amount of lithium in the spectra of six dwarf stars. We present the spectral analysis, including measurements of radial velocities, atmospheric parameters and lithium abundances. Then we estimate the ages of our targets from the Hertzsprung-Russell diagram and with the lithium test, present a selection of promising runaway star candidates and draw constraints on the number of ejected runaway stars compared to model expectations.