Periodicity in XTE J0421+560/CI Cam
ATel #820; J. Z. Yan and Q. Z. Liu (Purple Mountain Obs., China)
on 24 May 2006; 01:33 UT
Credential Certification: Qingzhong Liu (qzliu@pmo.ac.cn)
Subjects: Optical, X-ray, Binary, Black Hole, Neutron Star, Star, Transient, Variables
Referred to by ATel #: 1381
We analyze the RXTE ASM one-day average light curve of XTE J0421+560/CI Cam. A period of 377+/-7 day is found by using the PDM method (phase dispersion minimization, R. F. Stellingwerf, 1978, ApJ, 224, 953). This period may be the orbital period of the binary system. Several weak flare events could be clearly seen on the 2-12 keV RXTE ASM light curve. This periodic outburst is similar to the faint Type I outburst in Be/X-ray binaries. The optical light curve of CI Cam was reported by Barsukova, E. A. et al. (ATEL #416). Similar variation with a period of 372+/-15 day is also found by us in the light curve.
XTE J0421+560/CI Cam is a peculiar B[e]/X-ray transient. Since its 1998 strong outburst in all wavelength bands, it rapidly went into its quiescent state. We have observed the object since 2001. Strong spectral variations are detected, which probably related to the periodic activity in the X-ray and the optical photometry.
