V803 Aquilae: A Newborn W Ursae Majoris Siamese Twin?

• Published in: Publications of the Astronomical Society of the Pacific 1993-12, Vol.105 (694), p.1441-1455
• Main Authors: Samec, Ronald G., Su, Wen, Dewitt, Jason R.
• Format: Article
• Language: English
• Subjects: Astronomical magnitude; Astronomical photometry; Astronomy; Binary and multiple stars; Comparison stars; Earth, ocean, space; Eclipses; Eclipsing binaries; Ephemerides; Exact sciences and technology; Light curves; Mass ratio; Mathematical minima; Stars; Variable stars
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1086/133327

A complete photometric analysis of BVRI photometry of the physically compact, eclipsing binary V8O3 Aquilae is presented. Six mean epochs of minimum light were determined from observations covering three primary and three secondary eclipses. A period study covering 54 years of observation or nearly 77,000 orbital revolutions reveals three distinct eras of constant period with two major period jumps of + 0.1 s and — 0.3 s. The light curves show that the primary and secondary eclipse depths are identical in V, and are nearly identical in B R, and I, indicating that the components have nearly the same temperatures. Standard magnitudes were determined and a reddening estimate was made. A simultaneous solution of the four light curves was computed using the Wilson-Devinney synthetic light-curve code. The solution indicates that the system consists of twin ~ K4 stars in shallow contact with a fill-out factor of ~ 8 % . A mass ratio of 1.000 was computed with a negligible temperature difference of only 6 K. Thus, based on our purely photometric solution, V8O3 Aql is made up of "Siamese" (contact) twin components. Theory would indicate that the twins have just recently come into contact, and the lack of other equal-mass W Ursae Majoris systems would indicate that it is in a very transient or unusual state.