Spectroscopic study of the O-type runaway supergiant HD 195592

TL;DR

This study provides detailed spectroscopic evidence that the O-type supergiant HD 195592 is a binary system with potential additional variability caused by a wider orbit companion or stellar wind effects.

Contribution

It offers the first detailed spectroscopic analysis of HD 195592, revealing its binary nature and characterizing its line profile variability and potential multiplicity.

Findings

Detection of spectroscopic binary signature in He I line

Radial velocity variations with 5.063 and ~20 days

Significant line profile variability related to radial velocity changes

Abstract

The scope of this paper is to perform a detailed spectroscopic study of the northern O-type supergiant HD 195592. We use a large sample of high quality spectra in order to investigate its multiplicity, and to probe the line profile variability. Our analysis reveals a clear spectroscopic binary signature in the profile of the He {\sc i} $\lambda$ 6678 line, pointing to a probable O + B system. We report on low amplitude radial velocity variations in every strong absorption line in the blue spectrum of HD 195592. These variations are ruled by two time-scales respectively of 5.063 and about 20 days. The former is firmly established, whilst the latter is poorly constrained. We report also on a very significant line profile variability of the H $\beta$ line, with time scales strongly related to those of the radial velocities. Our results provide significant evidence that HD 195592 is a binary system, with a period that might be the variability time-scale of about 5 days. The second time scale may be the signature of an additional star moving along a wider orbit provided its mass is low enough, even though direct evidence for the presence of a third star is still lacking. Alternatively, the second time-scale may be the signature of a variability intrinsic to the stellar wind of the primary, potentially related to the stellar rotation.