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Analysis of Light Curves of DQ Herculis Based on Five-Colour Photometry in 1982-1985статья
- Автор: Dmitrienko E.
- Сборник: Eruptive Phenomena in Stars , EDITED by L. SZABADOS
- Серия: Communications of the Konkoly Observatory
- Том: 86
- Год издания: 1986
- Место издания: BUDAPEST - SZABADSAGHEGY, Konkoly Observatory of the HUNGARIAN ACADEMY OF SCIENCES BUDAPEST
- Первая страница: 357
- Последняя страница: 358
- Аннотация: The light curves of DQ Her with a time resolution of 12-45 s in five broad band filters close to the standard UBVRI system using 1.25 m and 2.6 m reflectors were observed at the Crimean Astrophysical Observatory by Dmitrienko, Efimov, Shakhovskoy in 1982-1985. The photometer-polarimeter of Helsinki Observatory was used. The instrumentation and observations of 1982-1983 are available in the literature (Dmitrienko et al., 1985). The observations of 1984-1985 and an analysis of all available photometric data are due to be published elsewhere (Dmitrienko, 1986). Here we give some results of this analysis: (1) There is day-, month-, and year-scale variability. The out-of-eclipse light of DQ Her itself in 1982-83 became brighter compared with that in 1978 and was near the light level of 1954. In 1984-85 it decreased to the level of 1978. The mid-eclipse light level of DQ Her changed insignificantly. Hence, it is an eclipsed source which is variable: the primary, the side of the secondary which is turned to the primary and the gaseous stream. (2) The shape of the primary minima suggests the possibility of a total eclipse for several minutes. However, the mid-eclipse colours U-B, B-V indicate that a blue source is strong still. This may be due to the presence of a common gaseous envelope around the components. (3) Compared with 1954 (Walker, 1956) and 1975 (Nelson, Olson, 1976), in 1982-85 the greater shoulder is observed only at the ingress into eclipse. This implies the relative stabilization of the hot spot on the disk in 1982-85. (4) All light curves observed in 1982-85 can be classified into three types (see Fig. I). Types 1-3 have the lowest, intermediate and greatest values of out-of-eclipse light level (L) at phases near 0.45 and it is different from the level at phases near 0.2. The relative height of the shoulder (AH) at phases near 0.89 is intermediate, greatest and lowest for types 1-3. Values of L, AH of 1978 (observations by Schneider and Greenstein, 1979) allow one to suppose type 1. The progressive change of DQ Her status corresponds to the evolution of light curves practically at the same time for all five colours from type 1 (1978) through type 2 (25-27 May to 18-19 July 1982) to type 3 (19-20 July 1982) and back through type 2 (13-15 Sep 1982, to 13-14 Aug 1983) to type 1 (28-29 Apr 1984 and 18-19 May, 18-22 May 1985). It is necessary to emphasize that observations can give us only the upper limit for the time-scale variability and the lowest limit for the light-scale one. The full transition "type 1 - type 3" indicates an increase of the brightness of the eclipsed source of about 70%.
- Добавил в систему: Дмитриенко Елена Сергеевна