Photometric Properties of the HW Vir-type Binary OGLE-GD-ECL-11388. (7th December 2016)

• Record Type: Journal Article
• Authors: Hong, Kyeongsoo; Lee, Jae Woo; Lee, Dong-Joo; Kim, Seung-Lee; Koo, Jae-Rim; Park, Jang-Ho; Lee, Chung-Uk; Kim, Dong-Jin; Cha, Sang-Mok; Lee, Yongseok
• Is Part Of: Publications of the Astronomical Society of the Pacific. Volume 129:Number 971(2017)
• Publication Date: 2016-12-07
• Subjects: (stars:) binaries (including multiple): close -- (stars:) binaries: eclipsing -- stars: individual (OGLE-GD-ECL-11388) < Stars -- (stars:) planetary systems; Astronomy -- Periodicals; Astronomy; Periodicals; Periodicals; 520.5
• DOI: 10.1088/1538-3873/129/971/014202
• Languages: English
• ISSNs: 0004-6280

Abstract

Abstract: We present the first extensive photometric results for the eclipsing binary OGLE-GD-ECL-11388 with a period of about 3.5 hours located in the Galactic disk. For the photometric solutions, we obtained the BVI light curves from both the KMTNet observations in 2015 and the OGLE-III survey data from 2001–2009, which show striking reflection effects and very sharp eclipses. The light curve synthesis indicates that the eclipsing system is a HW Vir-type binary with a mass ratio of q = 0.289, an orbital inclination of i = 81.9 deg, and a temperature ratio between both components of T 2 / T 1 = 0.091. A frequency analysis was applied to the light residuals from our binary model; however, no pulsating periodicity from the subdwarf B-type primary component was detected under signal-to-noise amplitude ratios larger than 4.0. A total of 27 minimum epochs spanning 15 yr were used to analyze the eclipse timing variations of OGLE-GD-ECL-11388. It was found that the orbital period has varied due to a continuous period decrease at a rate of dP / dt = −1.1 × 10 −8 day yr −1 or a sinusoidal oscillation with a semiamplitude of K = 35 s and a cycle of P 3 = 8.9 yr. The period decrease may be explained by an angular momentum loss via magnetic stellar wind braking or may be only a part of the sinusoidal variation. We think the most likely interpretation of the orbital period change, at present, is the light-time effect via the presence of a third body with a mass of M 3 sin i 3 = 12.5 M Jup, putting it in the boundary zone between planets and brown dwarfs.