Cyclic Period Oscillation of the Eclipsing Dwarf Nova DV UMa

DV UMa is an eclipsing dwarf nova with an orbital period of similar to 2.06 hr, which lies just at the bottom edge of the period gap. To detect its orbital period changes, we present 12 new mid-eclipse times by using our CCD photometric data and archival data. The latest version of the O-C diagram, combined with the published mid-eclipse times in quiescence, and spanning similar to 30 years, was obtained and analyzed. The best fit to those available eclipse timings shows that the orbital period of DV UMa is undergoing a cyclic oscillation with a period of 17.58(+/- 0.52) years and an amplitude of 71.1(+/- 6.7) s. The periodic variation most likely arises from the light-travel-time effect via the presence of a circumbinary object, because the required energy to drive the Applegate mechanism is too high in this system. The mass of the unseen companion was derived as M-3 sin i' = 0.025(+/- 0.004) M.. If the third body is in the orbital plane (i.e., i' = i = 82 degrees.9) of the eclipsing pair, this would indicate it is a brown dwarf. This hypothetical brown dwarf is orbiting its host star at a separation of similar to 8.6 au in an eccentric orbit (e. = 0.44).