O. Maryeva,1,2 and P. Abolmasov3
1 Stavropol State University, Pushkina Str., 1, Stavropol, Russia 355009, Russia.
2 Special Astrophysical Observatory, Nizhnij Arkhyz, Zelenchukskij, Karachai–Cirkassian Republic, Russia 369167 (olga.maryeva@gmail.com).
3 Sternberg Astronomical Institute, Moscow State University, Universitetsky pr., 13, Moscow 119992, Russia (pavel.abolmasov@gmail.com).
Received 2010 February 3
Accepted 2010 June 10
RESUMEN
Combinamos observaciones espectroscópicas de archivo de la estrella LBV V532 (conocida como Estrella de Romano) con fotometría en la banda B. Los datos espectroscópicos cubren un intervalo de 15 años, desde 1992 hasta 2007. Mostramos que en máximo de brillo el objeto se comporta como una supergigante con líneas de emisión, mientras que en mínimo V532 se mueve a lo largo de la secuencia de las estrellas WN tardías. En este sentido, la estrella tiene un comportamiento similar al de las bien conocidas variables luminosas azules (LBV: luminous blue variables) AG Car y R 127, pero es un poco más caliente en mínimo. Identificamos unas 100 líneas espectrales en el intervalo 3700–7300 Å. Nuestra espectroscopia para este objeto es la más completa en la actualidad. Obtenemos la velocidad del viento usando las líneas del triplete de He I (300 ± 30 km s–1). También estimamos los parámetros físicos de la nebulosidad que rodea a V532.
ABSTRACT
We combine archival spectral observations of the LBV star V532 (Romano's star) together with existing photometric data in the B band. Spectroscopic data cover 15 years of observations (from 1992 to 2007). We show that the object in máximum of brightness behaves as an emission line supergiant while in mínimum V532 moves along the sequence of late WN stars. In this sense, the object behaves similarly to the well–known Luminous Blue Variable (LBV) stars AG Car and R127, but is somewhat hotter at the mínima. We identify about 100 spectral lines in the 3700 — 7300 Å wavelength range. As of today, our spectroscopy is the most comprehensive for this object. The velocity of the wind is derived using the He I triplet lines (360 ±30 km s–1). Physical parameters of the nébula around V532 are estimated.
Key Words: galaxies: individual (M33) — stars: individual (Romano's star) — stars: Wolf–Rayet — supergiants.
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