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title = "{Optical variability of WW Vul (Zaitseva+, 1997)}", journal = {VizieR Online Data Catalog}, keywords = {Stars: variable, Photometry: UBV}, yearстатья
- Авторы: ARTICLE1999yCat 90230277Z author Zaitseva, G V., Lyutyi V.M.
- Сборник: 30277}, adsurl = {http://adsabs.harvard.edu/abs/1999yCat..90230277Z}, adsnote = {Provided by the SAO/NASA Astrophysics Data System
- Том: 902
- Год издания: 1999
- Первая страница: pages
- Последняя страница: pages
- Аннотация: Abstract UBV observations of the X-ray binary system A0535+26/V725 Tau at the Crimean Station of the Sternberg Astronomical Institute in 1980-1998 are presented. Based on our and published data, we analyze the photometric history of the star from 1898. Over a period of 100 years, the star apparently showed all three activity phases (B, Be, Be-shell) of Be stars. We conclude that the X-ray activity of the object is attributable to the 1970-1997 outburst of the Be star due to envelope ejection. The star's colors during the minimum light of 1998 and its 1953-1956 colors (before the outburst) correspond to the spectral type B0-B1 at the color excesses E_{B-V} = 0.74 and E_{U-B} = 0.48, in agreement with the current spectral type O9.7. The minimum light of 1998 and the color excesses are used to determine the colors of the additional radiation, analyze their evolution during the 1973-1997 outburst, and refine the distance to the object (3 kpc). The colors of the additional radiation at maximum light of the star (1973-1980) match the colors of a hydrogen plasma with T_e = 1.5 x 10^4 K which is optically thick in the Balmer continuum. The brightness decline corresponds to a decrease in the optical depth of the plasma; at V = 9.1 mag, it becomes optically thin in the Balmer continuum with T_e = 10^4 K and N_e = 1010 - 1012 cm^{-3}. This conclusion is consistent with the model of a circumstellar envelope but is inconsistent with the existence of an accretion disk around the neutron star. All the additional radiation responsible for the optical variability is produced by a single source. The intensity of the H_alpha emission line at maximum light (1975-1980) is triple its intensity in 1987-1997, when quasi-periodic light fluctuations with P = 1400 days were observed. At this time, the line intensity correlated with brightness. The H_alpha line was in absorption at the minimum of 1998, and, at present, the star's active phase appears to have ended.
- Добавил в систему: Зайцева Галина Владимировна