Long-Term Monitoring of the Short Period SU UMa-Type Dwarf Nova, V844 Herculis

Oizumi, Shota; Omodaká, Toshihiro; Yamamoto, Hiroyuki; Tanada, Shunsuke; Yasuda, Tomoko; Arao, Yoshihiro; Kodama, Kie; SUZUKI, Mituru; Matsuo, Takeshi; Maehara, Hiroyuki; Nakajima, Kazuhiro; Dubovský, Pavol A.; Katô, Takeo; Imada, Akira; Kubota, Kaori; Sugiyasu, Kei; Morikawa, Koichi; Torii, K.; Uemura, Makoto; Ishioka, Ryoko; Tanabe, Kenji; Nogami, Daisaku

doi:10.1093/pasj/59.3.643

Cited by 13 publications

(4 citation statements)

References 42 publications

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“…Recently, it has been recognized that some SU UMa-type dwarf novae show an increasing superhump period change during a plateau phase of superoutburst (Semeniuk et al 1997;Nogami et al 1997). So far, we have confirmed this increase for about 15 SU UMa-type dwarf novae, most of which have their superhump periods shorter than 0.065 days (Oizumi et al 2007).…”

Section: Superhump Period Changesupporting

confidence: 63%

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CCD Photometry of a Newly Confirmed SU UMa-Type Dwarf Nova, NSV 4838

Imada

Yasuda

Omodaká

et al. 2009

Publications of the Astronomical Society of Japan

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We present time-resolved CCD photometry of a dwarf nova NSV 4838 (UMa 8, SDSS J102320.27+440509.8) during the 2005 June and 2007 February outburst. Both light curves showed superhumps with a mean period of 0.0699(1) days for the 2005 outburst and 0.069824(83) days for the 2007 outburst, respectively. Using its known orbital period of 0.0678 days, we estimated the mass ratio of the system to be q=0.13 based on an empirical relation. Although the majority of SU UMa-type dwarf novae having similar superhump periods show negative period derivatives, we found that the superhump period increased atṖ /P sh =+7(+3, -4)×10 −5 during the 2007 superoutburst. We also investigated long-term light curves of NSV 4838, from which we derived 340 days as a supercycle of this system.

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Section: Superhump Period Changesupporting

confidence: 63%

“…The location of NSV 4838 in this figure is designated as filled circles. The original data were taken fromOizumi et al (2007) (See alsoUemura et al (2005) for a comprehensive table of P dot values. ).…”

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confidence: 99%

CCD Photometry of a Newly Confirmed SU UMa-Type Dwarf Nova, NSV 4838

Imada

Yasuda

Omodaká

et al. 2009

Publications of the Astronomical Society of Japan

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“…We noticed a peculiar outburst activity, observed in several objects in Group X. It is known that V844 Her experiences only a few normal outbursts and that most of the outbursts are superoutbursts (Kato, Uemura 2000;Oizumi et al 2007). The disk instability model predicts that a system with a higher mass-transfer rate experiences more frequent normal outbursts (Osaki 1996).…”

Section: Objectsmentioning

confidence: 79%

Dwarf Novae in the Shortest Orbital Period Regime: I. A New Short Period Dwarf Nova, OT J055717+683226

Uemura,

Arai,

Kato

et al. 2009

Preprint

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We report the observation of a new dwarf nova, OT J055717+683226, during its first-ever recorded superoutburst in December 2006. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67 ± 0.03 min (0.05324 ± 0.00002 d). The next superoutburst was observed in March 2008. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be ∼ 480 d. The supercycle is much shorter than those of WZ Sge-type dwarf novae having supercycles of > ∼ 10 yr, which are a major population of dwarf novae in the shortest orbital period regime ( < ∼ 85 min). Using a hierarchical cluster analysis, we identified seven groups of dwarf novae in the shortest orbital period regime. We identified a small group of objects that have short supercycles, small outburst amplitudes, and large superhump period excesses, compared with those of WZ Sge stars. OT J055717+683226 probably belongs to this group.

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“…It has a very short orbital period of 78.69 minutes (Thorstensen et al 2002). Oizumi et al (2007) noted that normal outbursts from V844 Her are rare and that the time between super-outbursts is about 300 days.…”

Section: Introductionmentioning

confidence: 99%

A Surprising Periodicity Detected during a Super-outburst of V844 Herculis by TESS

Greiveldinger,

Garnavich,

Littlefield

et al. 2023

ApJ

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We identify a previously undetected periodicity at a frequency of 49.08 ± 0.01 days−1 (period of 29.34 ± 0.01 minutes) during a super-outburst of V844 Her observed by TESS. V844 Her is an SU UMa type cataclysmic variable with an orbital period of 78.69 minutes, near the period minimum. The frequency of this new signal is constant in contrast to the superhump oscillations commonly seen in SU UMa outbursts. We searched without success for oscillations during quiescence using MDM, TESS, and XMM-Newton data. The lack of a periodic signal in the XMM light curve and the relatively low X-ray luminosity of V844 Her suggest that it is not a typical IP. We consider the possibility that the 29-minute signal is the result of super-Nyquist sampling of a dwarf nova oscillation with a period near the 2-minute cadence of the TESS data. Our analysis of archival AAVSO photometry from a 2006 super-outburst supports the existence of a 29-minute oscillation, although a published study of an earlier super-outburst did not detect the signal. We compare the X-ray properties of V844 Her with short orbital period intermediate polars (IP), V1025 Cen and DW Cnc. We conclude that the new signal is a real photometric oscillation coming from the V844 Her system and that it is unlikely to be an aliased high-frequency oscillation. The steady frequency of the new signal suggests that its origin is related to an asynchronously rotating white dwarf in V844 Her, although the precise mechanism producing the flux variations remains unclear.

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Long-Term Monitoring of the Short Period SU UMa-Type Dwarf Nova, V844 Herculis

Cited by 13 publications

References 42 publications

CCD Photometry of a Newly Confirmed SU UMa-Type Dwarf Nova, NSV 4838

CCD Photometry of a Newly Confirmed SU UMa-Type Dwarf Nova, NSV 4838

Dwarf Novae in the Shortest Orbital Period Regime: I. A New Short Period Dwarf Nova, OT J055717+683226

A Surprising Periodicity Detected during a Super-outburst of V844 Herculis by TESS

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