The Origin of B-type Runaway Stars: Non-LTE Abundances as a Diagnostic

Catherine M. McEvoy, Philip L. Dufton, Jonathan V. Smoker, David L. Lambert, Francis P. Keenan, Fabian R. N. Schneider, Willem-Jan de Wit

Research output: Contribution to journalArticle

5 Citations (Scopus)
186 Downloads (Pure)

Abstract

There are two accepted mechanisms to explain the origin of runaway OB-type stars: the binary supernova (SN) scenario and the cluster ejection scenario. In the former, an SN explosion within a close binary ejects the secondary star, while in the latter close multibody interactions in a dense cluster cause one or more of the stars to be ejected from the region at high velocity. Both mechanisms have the potential to affect the surface composition of the runaway star. tlusty non-LTE model atmosphere calculations have been used to determine the atmospheric parameters and the C, N, Mg, and Si abundances for a sample of B-type runaways. These same analytical tools were used by Hunter et al. for their analysis of 50 B-type open-cluster Galactic stars (i.e., nonrunaways). Effective temperatures were deduced using the Si-ionization balance technique, surface gravities from Balmer line profiles, and microturbulent velocities derived using the Si spectrum. The runaways show no obvious abundance anomalies when compared with stars in the open clusters. The runaways do show a spread in composition that almost certainly reflects the Galactic abundance gradient and a range in the birthplaces of the runaways in the Galactic disk. Since the observed Galactic abundance gradients of C, N, Mg, and Si are of a similar magnitude, the abundance ratios (e.g., N/Mg) are as obtained essentially uniform across the sample.
Original languageEnglish
Article number32
Number of pages13
JournalThe Astrophysical Journal
Volume842
Issue number1
DOIs
Publication statusPublished - 09 Jun 2017

Keywords

  • stars: atmospheres
  • stars: early-type
  • stars: rotation
  • stars: kinematics and dynamics

Fingerprint Dive into the research topics of 'The Origin of B-type Runaway Stars: Non-LTE Abundances as a Diagnostic'. Together they form a unique fingerprint.

  • Cite this