Long-term Properties of Accretion Disks in X-ray Binaries: I. the variable third period in SMC X-1

W. I. Clarkson, P. A. Charles, M. J. Coe +3

Long term X-ray monitoring data from the RXTE ASM and CGRO BATSE reveal that the third (superorbital) period in SMC X-1 is not constant, but varies between 40-60 days. A dynamic po…