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

Document Type

Article

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