The LBV nature of Romano's star (GR 290) in M 33 ^*

¹ Istituto di Astrofisica Spaziale e Fisica Cosmica, CNR, via Fosso del Cavaliere 100, 00133, Roma, Italy
² Bologna Astronomical Observatory, INAF, Loiano Observing Station, Loiano, Italy
³ Dunsink Observatory, Castleknock, Dublin 15, Ireland
⁴ Dipartimento di Fisica, Università di Roma La Sapienza, Pz.le Aldo Moro 3, 00185 Roma, Italy

Corresponding author: V. F. Polcaro, polcaro@rm.iasf.cnr.it

Received: 26 May 2003
Accepted: 23 July 2003

Abstract

We report the first spectroscopic study of the LBV candidate GR 290 in M 33 (“Romano's star”) taken in February 2003, showing, besides prominent hydrogen and He  i emission lines, the 4630–60 Å blend and weak He  ii 4686 Å emission typical of Of stars. Our broad–band photometry shows that the star was observed during a phase of minimum optical luminosity, with , and a slightly positive colour index, which we tentatively attribute to an anomalous continuum energy distribution. We argue that GR 290 is indeed an LBV star presently in a high temperature phase, that should be followed – also in a short time – by ample spectroscopic and associated photometric variations.