MWC 930 -- a new luminous blue variable candidate
Abstract
We present the results of optical high-resolution and near-infrared low-resolution spectroscopy and multicolour optical and near-infrared photometry of the emission-line star MWC 930. The spectrum is rich with Fe ii emissions, most of which have P Cyg-type profiles. The emission lines are strong and narrow, indicating a powerful stellar wind with a low terminal velocity (υ∞~ 140 km s−1). The photospheric absorption lines are broad and show splitting, which might be due to the object's binarity. MWC 930 is most probably located in the Norma spiral arm at a distance of D= 3–4 kpc. This strong and slow wind as well as the star's luminosity (log L/L⊙~ 5.5) and the infrared excess shape suggest that MWC 930 is an unusual B-type supergiant, most likely undergoing the luminous blue variable evolutionary phase.