Long-Term Variation of the Spin Period of a Magnetic Cataclysmic Variable, MU Camelopardalis

Abstract

Results of an analysis of 11 nights of R-filter CCD photometry data of an intermediate polar MU Camelopardalis (MU Cam) obtained at the Korean 1.0 m telescope at Mt. Lemmon are reported. After checking the spin period with our data, Pspin =0.d01373801(59), we compiled the reported data of maxima timing and an O-C diagram analysis has been carried out to understand the spin period variation. A significant spin period variation was detected, and fitting the O-C points to a cubic parabola led to an ephemeris of BJDmax = 2453682.4178(94)+0.0137380(13)E-2.07(55)x10^(-11)xE^2+2.28(52)x10^(-15)xE^3. The torque experienced by the magnetic compact star accreting in a disk is estimated as τ ≈1.815×10^35 g cm2 / s2 in a simple approximation in order to show how important monitoring the period variation is. Thus we conclude that monitoring the long-term spin period variation will help to understand the physical condition of magnetic compact stars.

Keywords

• cataclysmic variables
• intermediate polar
• period variation
• O-C diagram