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تسجيل مستخدم جديدV729 Sgr: A long period dwarf nova showing negative superhumps during quiescence
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We report K2 observations of the eclipsing cataclysmic variable V729 Sgr which covered nearly 80 days in duration. We find five short outbursts and two long outbursts, one of which shows a clear plateau phase in the rise to maximum brightness. The mean time between successive short outbursts is ~10 d while the time between the two long outbursts is ~38 d. The frequency of these outbursts are unprecedented for a CV above the orbital period gap. We find evidence that the mid-point of the eclipse occurs systematically earlier in outburst than in quiescence. During five of the six quiescent epochs we find evidence for a second photometric period which is roughly 5 percent shorter than the 4.16 h orbital period which we attribute to negative superhumps. V729 Sgr is therefore one of the longest period CVs to show negative superhumps during quiescence.
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We present the analysis results of an eclipsing cataclysmic variable (CV) V729 Sgr, based on our observations and AAVSO data. Some outburst parameters were determined such as outburst amplitude ($A_{n}$) and recurrence time ($T_{n}$), and then the re
lationship between $A_{n}$ and $T_{n}$ is discussed. A cursory examination for the long-term light curves reveals that there are small-amplitude outbursts and dips present, which is similar to the behaviors seen in some nova-like CVs (NLs). More detailed inspection suggests that the outbursts in V729 Sgr may be Type A (outside-in) with a rise time $sim1.76$ d. Further analysis also shows that V729 Sgr is an intermediate between dwarf nova and NLs, and we constrain its mass transfer rate to $1.59times10^{-9} < dot{M}_{2} < 5.8times10^{-9}M_{odot}yr^{-1}$ by combining the theory for Z Cam type stars with observations. Moreover, the rapid oscillations in V729 Sgr were detected and analyzed for the first time. Our results indicate that the oscillation at $sim 25.5$ s is a true DNO, being associated with the accretion events. The classification of the oscillations at $sim 136$ and $154$ s as lpDNOs is based on the relation between $P_{lpDNOs}$ and $P_{DNOs}$. Meanwhile, the QPOs at the period of hundreds of seconds are also detected.
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