The First Multi-Color Photometric Study of the Near-Contact Binary as Serpentis
Abstract
The first complete multi-color CCD photometric light curves of the eclipsing binary AS Ser were obtained over three nights in 2005. Using the latest Wilson-Devinney (WD) code, we computed the photometric elements of this system. It turns out that AS Ser is a near-contact binary system with both components filling more than 99% of their Roche lobes. It belongs to a marginal contact binary system within the parameter uncertainties. The marginal characteristic of AS Ser reveals that this target may be in a rare phase predicted by the thermal relaxation oscillation (TRO) theory. The asymmetry of the light curves can be explained by a dark spot on the secondary component, which is consistent with its late-type nature. Combining all available times of light minimum, we derived a new orbital period of AS Ser and found a periodic oscillation varying within an amplitude of 0.0049 days and a period of 11.8 years. This period change may be the result of the light-time effect due to a presumed tertiary component (M 3 > 0.28M sun) or might result from magnetic activity cycles of the two components.
- Publication:
-
The Astronomical Journal
- Pub Date:
- July 2008
- DOI:
- 10.1088/0004-6256/136/1/337
- Bibcode:
- 2008AJ....136..337Z
- Keywords:
-
- binaries: close;
- binaries: eclipsing;
- stars: evolution;
- stars: individual: AS Serpentis