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TOPIC: V729 Sagittarii

Blobrana

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Posts: 131433

Date: May 10 11:08 2017

V729 Sgr	Permalink

Title: Long-term photometric behaviour of the eclipsing cataclysmic variable V729 Sgr Author: Han Zhongtao, Qian Shengbang, Lajús, E. Fernández, Voloshina Irina, Zhu Liying 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 relationship 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 behaviours 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 ~1.76 d. Further analysis also shows that V729 Sgr is an intermediate between dwarf nova and NLs, and we constrain its mass transfer rate to 1.59 x 10^-9 < M_2 < 5.8 x 10^-9 solar masses yr^-1 by combining the theory for Z Cam type stars with observations. Moreover, the rapid oscillations in V729 Sgr were detected and analysed for the first time. Our results indicate that the oscillation at ~25.5 s is a true DNO, being associated with the accretion events. The classification of the oscillations at ~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. Read more (254kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Apr 5 11:55 2017

V729 Sagittarii	Permalink

Title: V729 Sgr: A long period dwarf nova showing negative superhumps during quiescence Author: Gavin Ramsay (1), Matt A. Wood (2), John Cannizzo (3,4), Steve Howell (5), Alan Smale (6) ((1) Armagh Observatory, (2) Texas A and M University--Commerce, (3) NASA/GSFC, (4) University Maryland, (5) NASA Ames, (6) NASA/GSFC) 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. Read more (442kb, PDF) __________________

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