K. Mason, Mullard Space Science Laboratory; J. Middleditch, F. Cordova and K. Jensen, Los Alamos National Laboratory; G. Reichert and S. Bowyer, Berkeley Space Science Laboratory, University of California; P. Murdin, Royal Greenwich Observatory; and D. Clark, Rutherford Appleton Laboratory, write: "The Einstein x-ray sources E1405-451 and E1013-477, both initially discovered in the HEAO-1 Soft X-Ray Survey, have been optically identified with stars that resemble the AM Her class of magnetic cataclysmic variables. The positions and approximate V magnitudes of the optical objects are: R. A. (1950) Decl. V E1405-451 14 05 58.2 -45 03 06 15.5 E1013-477 10 13 57.24 -47 43 12.1 17 The optical light of E1405-451 is modulated with a period of 101.52 +/- 0.02 min. In white light, the modulation is quasisinusoidal with an amplitude of 1.2 mag (peak to peak). This broad modulation is less pronounced in the U band (Delta-m ~ 0.2), but a narrow (FWHM ~ 2.5 min), flat-bottomed, eclipse-like feature of Delta-m ~ 0.3 is coincident with the center of the broad minimum. There is flickering at all phases of the lightcurve with an amplitude as great as 0.3 mag, as well as 1-3 s quasiperiodic oscillations of 1.2 percent (rms) of the stellar light. The white light of E1013-477 is modulated with a period of 103.43 +/- 0.06 min and an amplitude of ~ 0.8 mag with flickering of amplitude as great as 0.6 mag superposed. The optical spectrum of both stars contains strong emission lines of H, He I and Ca II. The IUE spectrum of E1013-477 shows strong emission lines of C IV and Si IV. Both stars are excellent candidates for optical polarization studies."
International Astronomical Union Circular
- Pub Date:
- April 1982