Simultaneous X-Ray and Optical Observations of AN Ursae Majoris during a Low State

Authors

Paula Szkody, Einstein Observatory
Edward G. Schmidt, University of Nebraska at LincolnFollow
Lidia Crosa, Einstein Observatory
Robert Schommer, Kitt Peak National Observatory

Date of this Version

1981

Comments

Published in THE ASTROPHYSICAL JOURNAL 246:223-230, 1981 May 15, pp. 223-230. Copyright 1981 The American Astronomical Society. Used by permission.

Abstract

X-ray observations throughout the orbital cycle of AN UMa during its low state were conducted with the Einstein Observatory simultaneously with ground-based optical UBV photometry and spectroscopy. The observed low X-ray flux of 7 × 10^–13 ergs cm^–2 s^–1 is a factor of 40 below the high-state X-ray flux, and F_x/F_opt is about a factor of 50 lower than for AM Her and 2A 0311–227. There is marginal evidence for an X-ray eclipse coincident with an optical minimum and for increased X-ray flux at magnetic phase 0.4 which does not correlate with any optical continuum variation but may be related to increased hydrogen and helium line emission fluxes. Subject headings: stars: individual - X-rays: binaries