The orbital period analyses for two cataclysmic variables: UZ Fornacis and V348 Puppis inside Period Gap

Abstract

Four newest CCD eclipse timings of the white dwarf for polar UZ Fornacis and Six updated CCD mid-eclipse times for SW Sex type nova-like V348 Puppis are obtained. The detailed O-C analyses for both CVs inside period gap are made. Orbital period increases at a rate of $2.63(\pm 0.58)\times 10^{-11}s{s}^{-1}$ for UZ Fornacis and of $5.8(\pm 1.9)\times 10^{-12}s{s}^{-1}$ for V348 Puppis, respectively, are discovered in their new O-C diagrams. However, the conservative mass transfer from the secondary to the massive white dwarf cannot explain the observed orbital period increases for both CVs, which are regarded as part of modulations at longer periods. Moreover, the O-C diagram of UZ Fornacis shows a possible cyclical change with a period of $\sim 23.4(\pm 5.1)yr$. For explaining the observed cyclical period changes in UZ Fornacis, both mechanisms of magnetic activity cycles in the late-type secondary and the light travel-time effect are regarded as two probable causes. Not only does the modulation period 23.4yr obey the empirical correlation derived by \cite{lan99}, but also the estimated fractional period change $\Delta P/P\sim 7.3\times 10^{-7}$ displays a behavior similar to that of the CVs below the period gap. On the other hand, a calculation for the light travel-time effect implies that the tertiary component in UZ Fornacis may be a brown dwarf with a high confidence level, when the orbital inclination of the third body is larger than $16^{\circ }$.

17 pages, 7 figures, accepted for publication in Mon. Not. R. Astron. Soc

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• Theory of Low-Mass Stars and Substellar Objects
• High-Speed Energy-Resolved STJ Photometry of the Eclipsing Binary UZ For
• Cyclical period changes in HT Cas: a clear difference between systems above and below the period gap
• Superhumps in V348 Pup
• V348 Puppis: a new SW Sex star in the period gap
• XMM-Newton observes flaring in the polar UZ For during a low state
• Hubble Space Telescope Observations of the Nova-Like Cataclysmic Variable V348 Puppis

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