Discovery of the 10.6 hr orbital period of CAL87: an eclipsing low-mass X-ray binary in the Large Magellanic Cloud

Open Access
Publisher Website
Google Scholar
Abstract
We shown that the LMC low-mass X-ray binary CAL87 is an eclipsing system with a period of 10.6 hr. The primary eclipse is color-dependent, and there is also a secondary dip in the light curve, which we interpret as being due to occulation by a secondary bulge in the disc displaced ∼ 0.5 in phase from the primary bulge. We show that the optical properties of CAL87 are similar to the dipping and eclipsing LMXB X1822 – 371, although the temperature of their X-ray spectra differ by a factor of ∼ 100.