Open AccessPeriodic microvariation of B416, a new luminous blue variable in M33
Author(s) -
Shemmer Ohad,
Leibowitz Elia M.,
Szkody Paula
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03089.x
Subject(s) - physics , luminous blue variable , astrophysics , balmer series , brightness , variable star , astronomy , galaxy , stars , extinction (optical mineralogy) , amplitude , be star , light curve , flux (metallurgy) , emission spectrum , spectral line , optics , materials science , metallurgy
We report optical photometric and spectroscopic observations of the M33 star B416, establishing it as the fifth identified luminous blue variable (LBV) in that galaxy. The B magnitude of the star varies with a period of 8.26 d and an amplitude of 0.03 mag. The red end of the optical spectrum does not seem to partake in these oscillations, which we identify as the microvariations, known to persist in LBV stars. B416 is the first LBV with such oscillations that are strictly periodic and coherent over at least 10 years. The brightness of the star is also varying on a longer (years) time‐scale, again mainly in its blue light. The spectrum has most of the characteristics of an LBV in quiescence, showing Balmer, He i , Fe ii and [Fe ii ] emission lines. The flux and profile of some of these lines are varying, but the scarcity of the observations prevents us from establishing their characteristic time‐scale. B416 is at the centre of an H ii region, another indication of the relatively low age of this stellar system.