A Photometric Study of the Near-Contact Binary EX Aquarii
Volume 53 number 2 (2025)
- Edward J. Michaels
- Waffelow Creek Observatory, 10780 FM 1878, Nacogdoches, TX 75961; astroed@ejmj.net
Abstract
Presented are the first multi-band photometric observations of the eclipsing binary EX Aquarii. This star has an orbital period of 0.89 day with beta Lyrae-type light curves. The light is continuously changing except during the total eclipse that occurs at secondary minimum. Light curve analysis using the Wilson-Devinney program revealed a semidetached configuration with the cool K6 secondary star filling its Roche lobe. The F6 primary star nearly fills its lobe with a filling factor over 99%. This near-contact binary has a mass ratio of M2 / M1 = 0.302 and an orbital inclination of 88°. A period analysis of 23 minima timings found an orbital period that is increasing at a rate of dP / dt = + 1.3 × 10^–7 dyr^–1. The O–C curves showed a sinusoidal modulation of 14.1 yr and an amplitude of 0.0025 d, which indicate a possible tertiary component.