Discovery of two new Galactic candidate luminous blue variables with Wide-field Infrared Survey Explorer

Type Journal Article
Names V. V. Gvaramadze, A. Y. Kniazev, A. S. Miroshnichenko, L. N. Berdnikov, N. Langer, G. S. Stringfellow, H. Todt, W.-R. Hamann, E. K. Grebel, D. Buckley, L. Crause, S. Crawford, A. Gulbis, C. Hettlage, E. Hooper, T.-O. Husser, P. Kotze, N. Loaring, K.
Publication Monthly Notices of the Royal Astronomical Society
Volume 421
Pages 3325-3337
Journal Abbreviation Monthly Notices of the Royal Astronomical Society
Date April 1, 2012
DOI 10.1111/j.1365-2966.2012.20556.x;
ISSN 0035-8711
Library Catalog NASA ADS
Abstract We report the discovery of two new Galactic candidate luminous blue variable (LBV) stars via detection of circular shells (typical of confirmed and candidate LBVs) and follow-up spectroscopy of their central stars. The shells were detected at 22 μm in the archival data of the Mid-Infrared All Sky Survey carried out with the Wide-field Infrared Survey Explorer (WISE). Follow-up optical spectroscopy of the central stars of the shells conducted with the renewed Southern African Large Telescope (SALT) showed that their spectra are very similar to those of the well-known LBVs P Cygni and AG Car, and the recently discovered candidate LBV MN112, which implies the LBV classification for these stars as well. The LBV classification of both stars is supported by detection of their significant photometric variability: one of them brightened in the R and I bands by 0.68 ± 0.10 and 0.61 ± 0.04 mag, respectively, during the last 13-18 years, while the second one (known as Hen 3-1383) varies its B, V, R, I and Ks brightnesses by ≃0.5-0.9 mag on time-scales from 10 d to decades. We also found significant changes in the spectrum of Hen 3-1383 on a time-scale of ≃3 months, which provides additional support for the LBV classification of this star. Further spectrophotometric monitoring of both stars is required to firmly prove their LBV status. We discuss a connection between the location of massive stars in the field and their fast rotation, and suggest that the LBV activity of the newly discovered candidate LBVs might be directly related to their possible runaway status. a USNO B-1 (Monet et al. 2003); bDENIS; c2MASS; dSALT; ePROMPT.
Tags Be, LINE: IDENTIFICATION, Stars: Evolution, circumstellar matter, stars: emission-line, stars: individual: Hen 3-1383, stars: massive
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