Confirmation of the Luminous Blue Variable status of MWC 930

Abstract

We present spectroscopic and photometric observations of the emission-line star MWC 930 (V446 Sct) during its long-term optical brightening in 2006--2013. Based on our earlier data we suggested that the object has features found in Luminous Blue Variables (LBV), such as a high luminosity (~3 10^5 Lsun, a low wind terminal velocity (~ 140 km/s), and a tendency to show strong brightness variations (~1 mag over 20 years). For the last ~7 years it has been exhibiting a continuous optical and near-IR brightening along with a change of the emission-line spectrum appearance and cooling of the star's photosphere. We present the object's $V$--band light curve, analyze the spectral variations, and compare the observed properties with those of other recognized Galactic LBVs, such as AG Car and HR Car. Overall we conclude the MWC 930 is a bona fide Galactic LBV that is currently in the middle of an S Dor cycle.

arXiv comment12 pages, 7 figures

References in corpus (10)

• The AKARI/IRC Mid-Infrared All-Sky Survey
• On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle
• The All Sky Automated Survey
• Bona-fide, strong-variable galactic Luminous Blue Variable stars are fast rotators: detection of a high rotational velocity in HR Carinae
• New Herbig Ae/Be stars confirmed via high-resolution optical spectroscopy
• Long-term spectroscopic monitoring of the Luminous Blue Variable HD160529
• Accurate luminosities from the oxygen 7771-4 A triplet and the fundamental parameters of F-G supergiants
• The All Sky Automated Survey. The Catalog of Variable Stars. IV.18^h - 24^h Quarter of the Southern Hemisphere
• Spitzer observations of a circumstellar nebula around the candidate Luminous Blue Variable MWC 930
• Long-term Spectroscopic Monitoring of LBVs and LBV Candidates

Cited by in corpus (7)

• Gaia DR2 study of Herbig Ae/Be stars
• Multiplicity of Galactic Luminous Blue Variable stars
• The 2018 Census of Luminous Blue Variables
• Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy
• WS1: one more new Galactic bona fide luminous blue variable
• Luminous Blue Variables
• Skynet Algorithm for Single-Dish Radio Mapping I: Contaminant-Cleaning, Mapping, and Photometering Small-Scale Structures