Статья

Spectroscopy and photometry of the emission–line B–typestars AS 78 and MWC 657

А. С. МирошниченкоCentral Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140, Saint-Petersburg, RussiaЕ. Л. ЧенцовIsaak Newton Institute of Chile, SAO branch, ChileВ. Г. КлочковаIsaak Newton Institute of Chile, SAO branch, ChileK. S. KuratovFesenkov Astrophysical Institute of the National Academy of Sciences, Kamenskoe plato, Almaty, 480068, KazakhstanT. A. SheikinaFesenkov Astrophysical Institute of the National Academy of Sciences, Kamenskoe plato, Almaty, 480068, KazakhstanD. B. MukanovAl-Farabi Kazakh National State University, Almaty, 480000, KazakhstanK. S. BjorkmanRitter Observatory, Dept. of Physics & Astronomy, University of Toledo, Toledo, OH 43606, U.S.AR. O. GrayDept. of Physics and Astronomy, Appalachian State University, Boone, NC 28608, U.S.AR. J. RudyAerospace Corp. M2/266, P.O. Box 92957, Los Angeles, CA 90009, U.S.AD. K. LynchAerospace Corp. M2/266, P.O. Box 92957, Los Angeles, CA 90009, U.S.AS. MazukAerospace Corp. M2/266, P.O. Box 92957, Los Angeles, CA 90009, U.S.AR. C. PuetterCenter for Astrophysics and Space Sciences, University of California, San Diego, C-0111, La Jolla, CA 92093, U.S.AP. García-LarioISO Data Centre, Astrophysics Division, Space Science Department of ESA, Villafranca del Castillo, Apartado de Correos 50727, E-28080 Madrid, SpainJ. V. PereaYu. K. BergnerCentral Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140, Saint-Petersburg, Russia

2000en

ABI

Аннотация

We present the results of low- and high-resolution spectroscopic and multicolour photometric observations of two early-type emission-line stars, AS 78 and MWC 657. They were identified by Dong & Hu (1991) with the IRAS sources 03549+5602 and 22407+6008, respectively, among many other sources displaying a very strong infrared excess, 8 mag AS 78 is recognized as a photometric variable for the first time. A large near-IR excess radiation is detected in AS 78 and confirmed by new, higher-quality, data for MWC 657. Significant variations in the Balmer line profiles are detected for both objects. Modelling of the Balmer line profiles of AS 78 obtained in 1994 yields the following parameters of the star and its wind: K, log Lbol/ 4.0, ~ 10-6 yr-1. The photometric and new spectroscopic data indicate that the star's Teff increases with time, while the stellar wind changes its structure. Distances towards both objects are estimated on the basis of their radial velocities and the galactic rotation curve. Consideration of different options about the nature and evolutionary state of both objects leads us to suggest that they are binary systems containing a B-type intermediate-luminosity star and a gaseous disk around the less luminous component.

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Идентификаторы

DOI: 10.1051/aas:2000287

Цитирования и источники

Цитирований: 3Использованных источников: 0

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