Evolution of Negative Superhumps, Quasiperiodic Oscillations, and Outbursts in the Z Cam-type Dwarf Nova AH Her

Sun, Qi-Bin; Qian, Sheng-Bang; Li, Min-Yu

doi:10.3847/1538-4357/ace183

Cited by 3 publications

(7 citation statements)

References 55 publications

(57 reference statements)

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“…In our recent work (Sun et al 2023a), we found that an NSH was present in both outbursts and quiescence of AH Her and varied with the outburst. The NSH amplitude is most prominent during quiescence, weakens as the outburst rises, is undetectable at the top, rebounds and weakens during the plateau, and strengthens again as the outburst weakens.…”

Section: Nsh and Dn Outburstsmentioning

confidence: 73%

“…However, Ramsay et al (2017) and Court et al (2020) studied Z Cam-type DNe V729 Sgr and EX Dra and both found NSHs only in quiescence and not during outbursts, demonstrating that there is no consensus on the existence of NSHs during DN outbursts. Our recent work found that the NSHs in the Z Cam-type DN AH Her change as the outburst progresses (Sun et al 2023a). Therefore, we suggest that the relationship between NSHs and DN outbursts is a window into the study of DN outbursts and the origin of NSHs.…”

Section: Introductionmentioning

confidence: 69%

“…(v) As in our recent work, Gaussian fitting was used to compute the maxima and minima of each NSH and finally to obtain the amplitude of the NSHs (Sun et al 2023a).…”

Section: Analysis and Resultsmentioning

confidence: 99%

“…Figure 1(c): areas a and b) but do not affect the overall NSH trend.We use the same approach as in recent work(Sun et al 2023a), using Gaussian fitting to compute the maxima and minima of each NSH in the light curve after removal of the orbital signal (see Figure1(d)), and ultimately to obtain the amplitude of each NSH (see Figure 1(e)). Finally, the CWT was used to analyze the light curve after removal of the non-NSH signal to obtain the evolution of the NSH amplitude with time (see Figure 1(f)).…”

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confidence: 99%

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Nine New Cataclysmic Variable Stars with Negative Superhumps

Sun,

Qian,

Zhu

et al. 2024

ApJ

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Negative superhumps (NSHs) are signals a few percent shorter than the orbital period of a binary star and are considered to originate from the reverse precession of the tilted disk. Based on TESS photometry, we find nine new cataclysmic variable stars with NSHs. Three (ASAS J1420, TZ Per, and V392 Hya) of these stars similar to AH Her still have NSHs during dwarf nova outbursts, and the NSH amplitude varies with the outburst. The variation in the radius of the accretion disk partially explains this phenomenon. However, it does not explain the rebound of the NSH amplitude after the peak of the outburst and the fact that the NSH amplitude of the quiescence is sometimes not the largest, and it is necessary to include the disk instability model (DIM) and add other ingredients. Therefore, we suggest that the variation of NSH amplitude with outburst can be an important basis for studying the origin of NSHs and improving the DIM. The six (ASASSN-V J1137, ASASSN-V J0611, 2MASS J0715, LAMOST J0925, ASASSN-17qj, and ZTF 18acakuxo) remaining stars have been poorly studied, and for the first time we determine their orbital periods, NSHs, and superorbital signal (SOR) periods. The NSH periods and amplitudes of ASASSN-V J1137 and ASASSN-17qj vary with the SOR, and based on the comparison of the observations with the theory, we suggest that a single change in tilted disk angle does not explain the observations of the SOR and that other ingredients need to be considered as well.

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Section: Nsh and Dn Outburstsmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 69%

“…(v) As in our recent work, Gaussian fitting was used to compute the maxima and minima of each NSH and finally to obtain the amplitude of the NSHs (Sun et al 2023a).…”

Section: Analysis and Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Nine New Cataclysmic Variable Stars with Negative Superhumps

Sun,

Qian,

Zhu

et al. 2024

ApJ

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“…Recently, we have carried out studies of NSHs based on survey data released by space telescopes (Sun et al 2023a(Sun et al , 2023c(Sun et al , 2024. We found that in NL SDSS J081256.85 +191157.8, eclipse depth, NSH amplitude, and O -C at the eclipse minima all varied periodically in response to changes in accretion disk precession, with the periodic changes in NSH amplitude being direct evidence for the origin of NSHs from tilted accretion disk precession (Sun et al 2023c).…”

Section: Introductionmentioning

confidence: 98%

A New Window for Studying Intermediate Polars and Tilted Accretion Disk Precession

Sun,

Qian,

Zhu

et al. 2024

ApJ

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TV Col is a long-period eclipsing intermediate polar (IP) prototype star for the negative superhump (NSH) system. We investigate the eclipse minima, eclipse depth, and NSH amplitude based on TESS photometry. Using the same analytical method as for SDSS J081256.85+191157.8, we find periodic variations of O − C for eclipse minima and NSH amplitudes with periods of 3.939(25) days and 3.907(30) days, respectively. The periodic variation of the NSH amplitude of TV Col confirms that periodic changes in NSH amplitude in response to the tilted disk precession may be universal, which is further evidence that the origin of the NSHs is related to the tilted disk precession. We suggest that the variation in NSH amplitude may be similar to the superorbital signal, coming from the periodic change in visual brightness of the energy released by streams touching the tilted disk with tilted disk precession. Finally, we find for the first time that the eclipse depth exhibits biperiodic variations with periods of P 1 = 3.905(11) days and P 2 = 1.953(4) days, respectively. P 2 is about half of P 1 and the disk precession period (P 1 ≈ P prec ≈ 2 × P 2). We suggest that P 1 may come from the periodic change in the brightness of the eclipse center due to tilted disk precession, while P 2 may come from two accretion curtains precessing together with the tilted disk, but more verification and discussion are necessary. The discovery of biperiodic variations in eclipse depth provides a new window for studying IPs and tilted disk precession.

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Tilted Disk Precession and Negative Superhumps in HS 2325+8205: A Multiwindow Analysis

Sun,

Qian,

Zhu

et al. 2024

ApJ

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Tilted disk precession exists in different objects. Negative superhumps (NSHs) in cataclysmic variable stars are believed to arise from the interaction between the reverse precession of a tilted disk and the streams from the secondary star. Utilizing Transiting Exoplanet Survey Satellite photometry, we present a comprehensive investigation into the tilted disk precession and NSHs in the dwarf nova (DN) HS 2325+8205, employing eclipse minima, eclipse depths, NSH frequencies, and NSH amplitudes and the correlation between them as the windows. We identified NSHs with a period of 0.185671(17) day in HS 2325+8205. The NSH frequency exhibits variability with a period of 3.943(9) days, akin to the tilted disk precession period validated in nova-like stars (SDSS J0812) and intermediate polars (IPs; TV Col). The O − C of the eclipse minima were similarly found to vary cyclically in a period of 4.135(5) days, characterized by a faster rise than fall. Furthermore, the NSH amplitude exhibits complex and diverse variations, which may be linked to changes in the disk radius, the mass transfer rate, and the apparent area of the hot spot. For the first time in DNe, we observe biperiodic variations in eclipse depth (P 1 = 4.131(4) days and P 2 = 2.065(2) days ≈ P prec/2) resembling those seen in IPs, suggesting that variations with P 2 are not attributable to an accretion curtain, as previously suspected. Moreover, NSH amplitude and eclipse depth decrease with increasing NSH frequency, while NSH amplitude correlates positively with eclipse depth. These complex variations observed across multiple observational windows provide substantial evidence for the understanding of tilted disk precession and NSHs.

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Evolution of Negative Superhumps, Quasiperiodic Oscillations, and Outbursts in the Z Cam-type Dwarf Nova AH Her

Cited by 3 publications

References 55 publications

Nine New Cataclysmic Variable Stars with Negative Superhumps

Nine New Cataclysmic Variable Stars with Negative Superhumps

A New Window for Studying Intermediate Polars and Tilted Accretion Disk Precession

Tilted Disk Precession and Negative Superhumps in HS 2325+8205: A Multiwindow Analysis

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