New deep minimum of Romano's Star in M33
ATel #5846; Massimo Calabresi (ARA, Associazione Romana Astrofili), Corinne Rossi (Phys. Dept., La Sapienza University, Roma), Roberto Gualandi, Silvia Galeti (INAF/OABo, Loiano Station, Bologna), Vito Francesco Polcaro, Roberto Viotti (INAF/IAPS, Roma), Raniero Albanesi, Fabio Anzellini, Roberto Haver, Paolo Caponetto, Roberto Gorelli (ARA)
on 3 Feb 2014; 11:28 UT
Credential Certification: Francesco Verrecchia (francesco.verrecchia@asdc.asi.it)
Subjects: Optical, Star, Variables
After the luminosity minimum of 2007-2008 (V=18.6, Polcaro et al. 2011, AJ, 141, 18) and a moderate luminosity maximum at beginning 2011 (V=17.8), the Luminous Blue Variable GR290/Romano's Star in M33 has reached a new deep minimum with V=18.7 and R=18.4 in December 2013 which appears to be the deepest so far recorded in its known light history.
Significant luminosity oscillations have been observed during the 2011-2013 declining phase.
With respect to the January 2011 maximum the star presently is weaker by almost one magnitude in all optical bands.
The 01 Jan. 2014 low-resolution spectrum taken at the Loiano Observatory is very similar to the 2008 minimum spectrum with strong HeII 468 nm line and NIII 464 nm triplet, confirming the present hot phase of the star. The anti-correlation between the intensity of the high excitation lines and the visual luminosity found by Polcaro et al. is then confirmed and strengthened.
We also report that the revised magnitudes of Var C in M33 (ATel #5403) for 11 Sept. 2013 are V=15.64 (0.06) and R=15.2 (0.1) (Franco Montagni, private communication).
