A period investigation of the overcontact binary system V417 Aquilae

¹ National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, PO Box 110, 650011 Kunming, PR China
² United Laboratory of Optical Astronomy, Chinese Academy of Science (ULOAC), 100012 Beijing, PR China

Corresponding author: Qian Shengbang, qsb@netease.com

Received: 4 November 2002
Accepted: 5 December 2002

Abstract

A detailed orbital period investigation of the short-period () W UMa type star, V417 Aql, is presented based on the analysis of its O–C data. It is shown that the period change of the binary system is continuous. A periodic variation, with a period of 42.4 years and an amplitude of , is found superimposed on a long-term period decrease ( days/year). The period oscillation can be explained either by the light-time effect via the presence of an unseen third body or by magnetic activity cycles of the components. V417 Aql is a W-type overcontact binary system with a low mass ratio of . The long-term period variation is in agreement with the conclusion of Qian ([CITE]b) that a low-mass ratio W-type system usually shows a secular period decrease. This suggests that V417 Aql is on the AML-controlled stage of the evolutionary scheme proposed by Qian ([CITE]b). Meanwhile, the light-curve paradox encountered by TRO theory is discussed.