!Eclipsing Binaries That Don't Eclipse Anymore: the Strange Case of the Once (and Future?) Eclipsing Binary QX Cassiopeiae (Abstract)

Volume 40 number 1 (2012)

Edward F. Guinan

Villanova University, Department of Astronomy, Villanova, PA 19085; edward.guinan@villanova.edu

Michael Bonaro

Villanova University, Department of Astronomy, Villanova, PA 19085; edward.guinan@villanova.edu

Scott G. Engle

Villanova University, Department of Astronomy, Villanova, PA 19085; edward.guinan@villanova.edu

Andrej Prsa

Villanova University, Department of Astronomy, Villanova, PA 19085; edward.guinan@villanova.edu

Abstract

(Abstract only) We report on the cessation of eclipses of the former 6.005-day eclipsing binary QX Cas. This 10th-magnitude star is a member of the young open cluster NGC 7790; in 1954 QX Cas (B1 IV–V + B3 V) was discovered by Erleksova (1954: Astr. Circ. 155) to be an eclipsing binary. Subsequently Sandage (1958: ApJ,128,150) and Sandage and Tammann (1969: ApJ, 157, 683) obtained accurate photometry of QX Cas that confirmed its eclipsing nature and provided accurate measures of UBV magnitudes and colors. The early light curves display two narrow eclipses with depths of ~ 0.32 magnitude and ~0.28 magnitude, respectively. Moreover the Min II occurs at 0.37 P—indicating an moderately eccentric orbit. To secure modern light curves, we have carried out UBVRI photometry using the 0.8-m Four College Automatic Photoelectric Telescope (FCAPT). Photometry was conducted on >110 nights and the observations now cover all the orbital phasespace of the binary. However, this photometry (and overviews of all recent photometry) show no evidence of eclipses. Thus QX Cas is no longer an eclipsing binary! QX Cas joins another former eclipsing binary—SS Lac—that over twenty years ago also ceased eclipsing.