[vsnet-alert 16339] M33 Var C outburst (ATEL)

[Taichi Kato]

   Chance to visually see a star in M33!
The VSNET format name is "M33varC"

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ATEL #5362							     ATEL #5362

Title:	Variable C in M33 in Eruption
Author:	R. M. Humphreys (Institute for Astrophysics, University of
		Minnesota), K . Weis, B. Burggraf, D. Bomans (Astronomisches Institut,
		Ruhr-Universitaet, Bochum),  J. C. Martin (University of Illinois,
		Springfield), H. Meusinger (Tautenburg Observatory) 
Queries:	roberta at umn.edu
Posted:	4 Sep 2013; 20:56 UT
Subjects:Optical, Star, Variables

The classical or normal LBV/S Doradus variable, Var C in M33 (Hubble &
Sandage 1953) has entered an LBV-type eruption or high mass loss phase
during which it increases in visual brightness and forms an optically thick
wind at maximum light.  In the past century Var C has experienced two long
duration maxima (1940 - 1953, 1982 - 1993:)  plus at least two briefer
brightenings. The most recent was in 2001-2005. See  Burggraf et al. 2013
(to be submitted) for the historic light curve and new observations up
to 2012.  The current eruption apparently began in late 2010 or early 2011.
Our spectrum from 03 Oct. 2010 shows hydrogen emission with P Cygni profiles,
Fe II emission plus absorption lines of He I, N II and Si IV, resembling
an early B-type supergiant. It was thus still in its quiescent or hot stage
at that time.  See also Clark et al. 2012.  Photometry, from the Tautenburg
Obs., from its minimum in 2009 - 2010 to the present show that it brightened
from V of 17.5 mag in Feb 2010 to 16.2 mag a year later in Feb 2011. The
most recent photometry from the Barber Obs. Springfield. Il., on 01 Sep
2013, yields V of 15.6 mag.and B of 15.9 mag. Current spectra are now needed
during its maximum light. 

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