Discrete absorption components in the massive LBV Binary MWC 314

TL;DR

This study analyzes discrete absorption components in the wind profiles of the LBV binary MWC 314, revealing their formation near the primary star and linking them to orbital motion and wind dynamics.

Contribution

It provides new observational evidence of DACs in MWC 314's wind and suggests their formation mechanisms related to binary interaction and wind structures.

Findings

DACs observed at specific wind velocities indicating high-temperature wind regions.

DACs appear when the primary star is in front of the secondary.

MWC 314 detected in X-rays with significant flux.

Abstract

We investigate the physical properties of large-scale wind structures around massive hot stars with radiatively-driven winds. We observe Discrete Absorption Components (DACs) in optical He I P Cygni lines of the LBV binary MWC 314 (Porb=60.8 d). The DACs are observed during orbital phases when the primary is in front of the secondary star. They appear at wind velocities between -100 km/s and -600 km/s in the P Cyg profiles of He I lam5875, lam6678, and lam4471, signaling high-temperature expanding wind regions of enhanced density and variable outflow velocity. The DACs can result from wave propagation linked to the orbital motion near the low-velocity wind base. The He I lines indicate DAC formation close to the primary's surface in high-temperature wind regions in front of its orbit, or in dynamical wind regions confined between the binary stars. We observed the DACs with Mercator-HERMES on 5 Sep 2009, 5 May 2012, and 6 May 2014 when the primary is in front of the secondary star. XMM-Newton observations of 6 May 2014 significantly detected MWC 314 in X-rays at an average rate of ~0.015 cts/s.