The Eclipsing System EP Andromedae and its Circumbinary Companions

摘要: We present new long-term CCD photometry for EP And acquired during the period 2007 to 2012. The light curves display total eclipses at primary minima and season-to-season variability. Our synthesis all available indicates that eclipsing pair is a W-type overcontact binary with parameters of q=2.578, i=83.3 deg, $\Delta T$=27 K, f=28 %, l3=2~3 %. asymmetric in were satisfactorily modeled by cool spot on either components from magnetic dynamo. Including our 95 timing measurements, 414 times minimum spanning about 82 yr used study. A detailed analysis eclipse diagram revealed orbital has varied as combination an upward-opening parabola two periodic variations, cycle lengths P3=44.6 P4=1.834 semi-amplitudes K3=0.0100 d K4=0.0039 d, respectively. observed increase fractional rate +1.39x10^{-10} excellent agreement calculated W-D code can be plausibly explained some mass transfer secondary star angular momentum loss due braking. most reasonable explanation both cycles light-travel-time effects driven possible existence third fourth component projected masses M3=0.25 Msun M4=0.90 Msun. more massive companion could using high-resolution spectroscopic data extending over course few years also itself. It circumbinary objects may have played important role formation evolution pair, which would cause it short initial thus evolve into configuration loss.