Rong-Xian Zhang

Photometric Study of AH Cancri, a W UMa-Type System in M67

We present time-series CCD photometry of AH Cnc, a W UMa–type binary system in the old open cluster M67. Over 3500 measurements in two filters were recorded on 15 nights from 2001 to 2004. From the data, 17 new times of minima for the eclipsing binary were obtained, from which a new ephemeris was derived. The orbital period of the system is refined as 0.36045754 days. A photometric analysis for the obtained light curves is performed based on the Wilson-Devinney code. The photometric solutions reveal a totally eclipsing contact configuration for AH Cnc. The photometric mass ratio is determined to be 0.149 ± 0.002. The masses and radii of the components are estimated as 1.21 ± 0.08 M⊙ and 1.36 ± 0.03 R⊙ for the primary and 0.18 ± 0.02 M⊙ and 0.62 ± 0.02 R⊙ for the secondary, respectively. The evolutionary status of the contact system is briefly discussed.

Long-term photometry of the near-contact detached binary GR Tauri

We present photometric observations of the eclipsing binary GR Tau made in 1985, 1993, 1998, 2000 and 2001. New times of minima and ephemerides are given. Based on a statistical analysis of the times of minima obtained by photoelectric and CCD photometry, the orbital period of the system is found to be decreasing with a rate of

TW Coronae Borealis: A Detached Near-Contact Binary System

\Delta P/P = 3.27 \times10^{-10}

The semi-detached binary system IU Per and its intrinsic oscillation

during the past decades. An assumed hot spot on the trailing hemisphere of the secondary enables us to reconstruct the peculiar asymmetry of the distorted light curves. The photometric solution with the Wilson-Devinney code reveals that GR Tau is a near-contact detached system with the two components almost filling their respective critical Roche lobes. The photometric mass ratio turns out to be

Spot Solutions for Two RS CVn Systems: ER Vul and V711 Tau

q=0.22

UBV photometric study of the extra large flare of HR 1099

, and the masses and radii are derived for the components as

Photoelectric photometry of the early-type semi-detached binary UW Orionis

M_{1}=1.42\pm 0.18~ M_{\odot}

Long-term photometric study of the W UMa binary star V523 Cas

,

The physical nature of the short‐period RS CVn system DV Psc

M_{2}=0.31\pm 0.04~ M_{\odot}

HL Aurigae: A near-contact binary system

,