LMC X-4
Abstract
R. L. Kelley, J. G. Jernigan, A. Levine, L. D. Petro and S. Rappaport, Massachusetts Institute of Technology, write: "Analysis of x-ray data obtained during a survey of the LMC in 1976 Feb. with the rmc aboard SAS 3 has revealed the presence of an x-ray pulsar with a period of 13.51 s. The four major LMC x-ray sources (LMC X-1 to X-4) were 'on' and in the field of view during the 6-day observation; however, the pulsations were detected with high statistical significance only during the 40-min x-ray flare from LMC X-4 reported by Epstein et al. (1977, Ap.J. 216, 103). We therefore identify LMC X-4 with the x-ray pulsar. The pulsed fraction is ~ 5 percent in the 2-11-keV energy band. A search for Doppler variations in the pulsation period due to the 1.4-day binary orbit is underway. In view of this development we urge optical observers to obtain refined measurements of the optical Doppler velocity of the companion star (Epstein et al. 1977, loc. cit.) and to search for optical pulsations at the 13.5-s period."
- Publication:
-
International Astronomical Union Circular
- Pub Date:
- September 1981
- Bibcode:
- 1981IAUC.3632....2K