The History Goes On: Century Long Study of Romano’s Star

Olga Maryeva,Massimo Calabresi,Gloria Koenigsberger,Corinne Rossi,Roberto Gualandi,Roberto F Viotti

doi:10.3390/galaxies7030079

Abstract

GR 290 (M 33 V0532 = Romano’s Star) is a unique variable star in the M33 galaxy, which simultaneously displays variability typical for luminous blue variable (LBV) stars and physical parameters typical for nitrogen-rich Wolf-Rayet (WR) stars (WN). As of now, GR 290 is the first object which is confidently classified as a post-LBV star. In this paper, we outline the main results achieved from extensive photometric and spectroscopic observations of the star: the structure and chemical composition of its wind and its evolution over time, the systematic increase of the bolometric luminosity during the light maxima, the circumstellar environment. These results show that the current state of Romano’s Star constitutes a fundamental link in the evolutionary path of very massive stars.

Highlights

GR 290 (M 33 V0532 = Romano’s Star)1 is a variable star in M 33 galaxy discovered by GiulianoRomano [1] who originally constructed its light curve and classified it as a Hubble-Sandage variable based on its photometric properties
In 1984, Peter Conti [2] introduced a new class of objects which assimilated Hubble-Sandage variables—luminous blue variables (LBV), and GR 290 became an LBV candidate [3,4]
Romano’s star displays both strong spectral and photometric variability, with several significant increases of brightness detected during its long monitoring (Polcaro et al [10] and references therein). Such variability is typical for LBV stars, while in the Hertzsprung-Russell (H-R)

Summary

Introduction

In 1984, Peter Conti [2] introduced a new class of objects which assimilated Hubble-Sandage variables—luminous blue variables (LBV), and GR 290 became an LBV candidate [3,4]. Romano’s star displays both strong spectral and photometric variability, with several significant (about 1.5–2 mag) increases of brightness detected during its long monitoring (Polcaro et al [10] and references therein). Such variability is typical for LBV stars, while in the Hertzsprung-Russell (H-R).

Stellar Vicinity of Romano’s Star

Photometry

10 January 2019

Spectroscopy and Determination of Physical Parameters

Nebula

Conclusions