* Astronomy

Title: A cyclical period variation detected in the updated orbital period analysis of TV Columbae
Authors: Zhibin Dai, Shengbang Qian, Eduardo Fernández Lajús, G. L. Baume

The two CCD photometries of the intermediate polar TV Columbae are made for obtaining the two updated eclipse timings with high precision. There is an interval time ~ 17yr since the last mid-eclipse time observed in 1991. Thus, the new mid-eclipse times can offer an opportunity to check the previous orbital ephemerides. A calculation indicates that the orbital ephemeris derived by Augusteijn et al. (1994) should be corrected. Based on the proper linear ephemeris (Hellier, 1993), the new orbital period analysis suggests a cyclical period variation in the O-C diagram of TV Columbae. Using Applegate's mechanism to explain the periodic oscillation in O-C diagram, the required energy is larger than that a M0-type star can afford over a complete variation period ~ 31.0 ±3.0 yr. Thus, the light travel-time effect indicates that the tertiary component in TV Columbae may be a dwarf with a low mass, which is near the mass lower limit ~ 0.08Msun as long as the inclination of the third body high enough.

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