X-Ray/Optical Studies of Two Outbursts of the Intermediate Polar YY (DO) Draconis

Szkody, Paula; Nishikida, Koichi; Erb, Dawn K.; Mukai, K.; Hellier, C.; Uemura, Makoto; Katô, Takeo; Павленко, Е. П.; Katysheva, N.; Shugarov, S. Yu.; Cook, Lewis M.

doi:10.1086/324733

Cited by 35 publications

(44 citation statements)

References 13 publications

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“…This outburst is one of the weakest (V = 11. m 2) observed (the brightest outburst (V = 9. m 7) occurs at JD 2 448 160). Similar values T decay = 0.84 days/mag may be estimated from the light curve of the outburst in November, 2000, which was published by Szkody et al (2002). A smaller value T decay = 0.641(2) was determined for the outburst in 2005 from the observations of Maehara (AFOEV 2007).…”

Section: Mean Outburst Profilesupporting

confidence: 79%

“…Basko & Sunyaev 1973;King & Lasota 1984). Results of X-ray/optical studies of two outbursts (1999 and 2000) were presented by Szkody et al (2002), who noted that the behaviour of the spin pulse amplitude with luminosity was unusual. Norton et al (1999) have split the group of intermediate polars into two subclasses with relatively large and relatively weak magnetic field and classified DO Dra as belonging to the second group (with DQ Her,V709 Cas et al).…”

Section: Article Published By Edp Sciencesmentioning

confidence: 99%

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Multiple timescales in cataclysmic binaries

Андронов

Chinarova

Han

et al. 2008

A&A

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Aims. We study the variability of the cataclysmic variable DO Dra, on time-scales of between minutes and decades. (15) d . We analyzed the profile of the "composite" (or "mean") outburst. We discovered however, that a variety of different outburst heights and durations had occurred, contrary to theoretical predictions. The analysis of the historical data has shown a correlation between the decay time dt/dm and the outburst maximum brightness with a slope d(dt/dm)/dm = 0.37(9). With increasing maximum brightness, we find that the decay time also increases; this is in contrast to the model predictions, which indicate that outbursts should have a constant shape. This is interpreted as representing the presence of outburst-to-outburst variability of the magnetospheric radius. A presence of a number of missed weak narrow outbursts is predicted from this statistical relationship. We tabulate characteristics of the "quasi-orbital" variations, which indicate that an amplitude maximum occurs between quiescence and the outburst peak. The semi-amplitude of the spin variability does not exceeded 0.02 mag. A new type of variability is detected, during 3 subsequent nights in 2007: periodic (during one nightly run) oscillations with rapidly-decreasing frequency from 86 to 47 cycles/day and a semi-amplitude increasing from 0. m 06 to 0. m 10, during a monotonic brightness increase from 14. m 27 to 14. m 13. This phenomenon was observed only during an unusually prolonged event of ∼1 mag brightening in 2007 (lasting till autumn), during which no (expected) outburst was detected. We refer to this behaviour as to the "transient periodic oscillations" (TPO). We attribute the frequency decrease to "beat"-type of the variability, probably caused by irradiation of a cloud that is spiralling down to the white dwarf. Its frequency would then increase and coverge towards the spin frequency. To study this new and interesting phenomenon, new regular photometric and spectral (in a "target of opportunity" mode) observations are required.

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Section: Mean Outburst Profilesupporting

confidence: 79%

Section: Article Published By Edp Sciencesmentioning

confidence: 99%

Multiple timescales in cataclysmic binaries

Андронов

Chinarova

Han

et al. 2008

A&A

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“…(1) Nogami et al (2009); (2) Kato et al (2015); (3) Ishioka et al (2002); (4) Crawford et al (2008); (5) Hellier et al (2000); (6) van Amerongen & van Paradijs (1989); (7) Andronov et al (2008); (8) Szkody & Mateo (1984); (9) Hudec et al (2005); (10) Hellier et al (1997); (11) Johnson et al (2017); (12) Šimon (2015).…”

Section: Observational Properties Of Ips and Outburstsmentioning

confidence: 99%

“…This conclusion relies, however, on the assumption that the whole mass-transfer stream is stopped at the outer disc edge, which is probably not correct, since it is very likely that the stream overflowing the disc interacts directly with the magnetosphere, as suggested by Hellier et al (2000), for example, in the case of EX Hya. This is nonetheless required to account for the X-ray emission accompanying the optical outbursts in systems such as EX Hys (Hellier et al 2000), YY Dra (Szkody et al 2002).…”

Section: Enhanced Mass-transfer Ratementioning

confidence: 99%

Dwarf nova outbursts in intermediate polars

Hameury

Lasota

2017

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Context. The disc instability model (DIM) has been very successful in explaining the dwarf nova outbursts observed in cataclysmic variables. When, as in intermediate polars, the accreting white dwarf is magnetised, the disc is truncated at the magnetospheric radius, but for mass-transfer rates corresponding to the thermal-viscous instability such systems should still exhibit dwarf-nova outbursts. Yet, the majority of intermediate polars, in which the magnetic field is not large enough to completely disrupt the accretion disc, seem to be stable, and the rare observed outbursts, in particular in systems with long orbital periods, are much shorter than normal dwarf-nova outbursts. Aims. We investigate the predictions of the disc instability model for intermediate polars in order to determine which of the observed properties of these systems can be explained by the DIM. Methods. We use our numerical code for the time evolution of accretion discs, modified to include the effects of the magnetic field, with constant or variable mass transfer from the secondary star. Results. We show that intermediate polars have mass transfer low enough and magnetic fields large enough to keep the accretion disc stable on the cold equilibrium branch. We show that the infrequent and short outbursts observed in long-period systems, such as, for example, TV Col, cannot be attributed to the thermal-viscous instability of the accretion disc, but instead have to be triggered by an enhanced mass-transfer from the secondary, or, more likely, by some instability coupling the white dwarf magnetic field with that generated by the magnetorotational instability operating in the accretion disc. Longer outbursts (a few days) could result from the disc instability.

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“…Outbursts of DNe usually occur semi-regularly. The presence of unusual CVs with DN-like outbursts, which significantly deviate from the canonical picture of DNe, has recently been receiving special attention (Ishioka et al 2002;Szkody et al 2002). Some of these objects have been proven to intermediate polars (IPs) (for recent reviews of IPs, see Patterson 1994;Hellier 1996), which contain weakly magnetized white dwarfs.…”

Section: Introductionmentioning

confidence: 99%

Two X-ray bright cataclysmic variables with unusual activities: GZ Cnc and NSV 10934

Katô

Dubovský²,

Stubbings³

et al. 2002

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Abstract. We report on a discovery of unexpected activities in two X-ray bright dwarf novae. GZ Cnc showed an anomalous clustering of outbursts in 2002, in contrast to a low outburst frequency in the past record. The activity resembles an increased activity seen in some intermediate polars or candidates. We identified NSV 10934, X-ray selected high-amplitude variable star, as a dwarf nova with unusually rapid decline. The outburst characteristics make NSV 10934 a twin of recently discovered intermediate polar (HT Cam) with dwarf nova-type outbursts. We propose that these activities in X-ray strong dwarf novae may be a previously overlooked manifestation of outburst activities in magnetic cataclysmic variables.

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X-Ray/Optical Studies of Two Outbursts of the Intermediate Polar YY (DO) Draconis

Cited by 35 publications

References 13 publications

Multiple timescales in cataclysmic binaries

Multiple timescales in cataclysmic binaries

Dwarf nova outbursts in intermediate polars

Two X-ray bright cataclysmic variables with unusual activities: GZ Cnc and NSV 10934

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