EDP Sciences
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Volume 383, Number 1, February III 2002
Page(s) 171 - 181
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011711

A&A 383, 171-181 (2002)
DOI: 10.1051/0004-6361:20011711

The luminous B[e] binary AS 381

A. S. Miroshnichenko1, 2, K. S. Bjorkman1, E. L. Chentsov3, 4, V. G. Klochkova3, 4, O. V. Ezhkova5, 6, R. O. Gray7, P. García-Lario8, J. V. Perea Calderón9, R. J. Rudy10, D. K. Lynch10, S. Mazuk10, C. C. Venturini10 and R. Puetter11

1  Ritter Observatory, Dept. of Physics & Astronomy, University of Toledo, Toledo, OH 43606-3390, USA
2  Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, Saint-Petersburg 196140, Russia
3  Special Astrophysical Observatory of the Russian Academy of Sciences, Karachai-Cirkassian Republic, Nizhnij Arkhyz 369167, Russia
4  Isaac Newton Institute of Chile, SAO Branch, Russia
5  Ulugh Beg Astronomical Institute of the Uzbek Academy of Sciences, Astronomicheskaya 33, Tashkent 700052, Uzbekistan
6  Issac Newton Institute of Chile, Uzbekistan Branch, Uzbekistan
7  Dept. of Physics and Astronomy, Appalachian State University, Boone, NC 28608, USA
8  ISO Data Centre, Astrophysics Division, Space Science Department of ESA, Villafranca del Castillo, Apartado de Correos 50727, 28080 Madrid, Spain
9  INSA S.A., Villafranca del Castillo, Apartado de Correos 50727, 28080 Madrid, Spain
10  The Aerospace Corp. M2/266, PO Box 92957, Los Angeles, CA 90009, USA
11  Center for Astrophysics and Space Sciences, University of California, San Diego, C-0111, La Jolla, CA 92093, USA

(Received 2 November 2001 / Accepted 22 November 2001)

We present the results of optical and near-IR spectroscopic and broadband multicolour photometric observations of the emission-line star AS 381. Its properties were found to be similar to those of Be stars with warm dust, a group of galactic objects recently defined by Sheikina et al. (2000). The spectrum of AS 381 indicates the presence of both a hot (early B-type) and a cool (K-type) star in the system. A high interstellar reddening ( $A_{V} \sim 7$ mag) suggests that it is located at a distance of $\ge$3 kpc, and the companions have luminosity types II or higher. The emission-line profiles indicate that the system is surrounded by a flattened circumstellar envelope, which is viewed close to pole-on. The hot companion is found to be ~2 mag brighter in the V-band and more massive (~ $20~M_{\odot}$) than the cool one (~7 $~M_{\odot}$). The strong line emission and position of the companions in the Hertzsprung-Russell diagram indicate that the system is experiencing mass exchange. We suggest that AS 381 is the first B[e] supergiant binary discovered in the Milky Way.

Key words: stars: emission-line, Be -- stars: individual: AS 381 -- techniques: spectroscopic -- techniques: photometric

Offprint request: A. S. Miroshnichenko, anatoly@physics.utoledo.edu

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© ESO 2002