Spectroscopy of 13 high mass stars in the Cyg OB2 association

TL;DR

This study uses high-resolution spectroscopy to analyze 13 massive stars in Cyg OB2, revealing details about their atmospheres, interstellar medium, and star formation, and suggesting the LBV nature of a hypergiant star.

Contribution

First high-resolution spectral analysis of 13 massive stars in Cyg OB2, confirming star formation scheme and identifying a hypergiant as an LBV candidate.

Findings

Velocity fields in stellar atmospheres and interstellar medium characterized.

Cascade star formation scheme for Cyg OB2 confirmed.

Hypergiant Cyg OB2 No.12 likely an LBV with circumstellar reddening.

Abstract

Aiming to explore weak spectral features of stellar and interstellar origin we used the NES echelle spectrograph of the 6-m telescope to obtain high-resolution spectra for 13 hot O3 - B4 stars in the Cyg OB2 association, including a high luminous star No. 12. Velocity fields in the atmospheres and interstellar medium, characteristics of optical spectra and line profiles are investigated. The cascade star formation scheme for the association is confirmed. Evidence is presented suggesting that the hypergiant Cyg OB2 No.12 is an LBV object and that its anomalous reddening has a circumstellar nature.