The K2 Light Curves and Stunted Outbursts of AC Cnc

Schlegel, Eric M.; Honeycutt, R. K.

doi:10.3847/1538-4357/ab17dd

Cited by 7 publications

(5 citation statements)

References 28 publications

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“…Hameury, Lasota (2014) explored for the first time the cause of "anomalous Z Cam phenomenon" and proposed a model in which the variation in mass transfer rates from the secondary star is responsible for that phenomenon. However, there is no positive evidence for triggering modulations of transfer rates, and also, the brightening of bright spots, which should occur simultaneously with the sudden increase of transfer rates, are observationally undetected (Honeycutt 2001;Schlegel, Honeycutt 2019). Hameury, Lasota (2014) have sought the cause of the light variations of IW And-type stars in the outside of the disk, i.e., enhanced mass transfer from the secondary star.…”

Section: Introductionmentioning

confidence: 99%

Thermal-viscous instability in tilted accretion disks: A possible application to IW Andromeda-type dwarf novae

Kimura

Osaki²,

Katô³

et al. 2020

Publications of the Astronomical Society of Japan

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IW And stars are a subgroup of dwarf novae characterized by repetitive light variations of the intermediate-brightness state with oscillations, which is terminated by brightening. This group of dwarf novae is also known to exhibit a wide variety even within one system in long-term light curves including usual dwarf-nova outbursts, Z Cam-type standstills, and so on, besides the typical IW And-type variations mentioned above. Following the recent observations suggesting that some IW And stars seem to have tilted disks, we have investigated how the thermalviscous instability works in tilted accretion disks in dwarf novae and whether it could reproduce the essential features of the light curves in IW And stars. By adopting various simplifying assumptions for tilted disks, we have performed time-dependent one-dimensional numerical simulations of a viscous disk by taking into account various mass supply patterns to the disk; that is, the gas stream from the secondary star flows not only to the outer edge of the disk but also to the inner portions of the disk. We find that tilted disks can achieve a new kind of accretion cycle, in which the inner disk almost always stays in the hot state while the outer disk repeats outbursts, thereby reproducing alternating mid-brightness interval sometimes with dips and brightening, which are quite reminiscent of the most characteristic observational light variations of IW And stars. Further, we have found that our simulations produce diverse light variations, depending on different mass supply patterns even without time variations in mass transfer rates. This could explain the wide variety in long-term light curves of IW And stars.

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Section: Introductionmentioning

confidence: 99%

Thermal-viscous instability in tilted accretion disks: A possible application to IW Andromeda-type dwarf novae

Kimura

Osaki²,

Katô³

et al. 2020

Publications of the Astronomical Society of Japan

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“…Similar kinds of dip events followed by the outbursts or brightenings were also seen in several CVs. Unlike the deep dips of HO Pup, where it loses 90% of its starlight, other CVs tend to reduce by only about 50% of their outburst brightness (Mason & Howell 2016;Schlegel & Honeycutt 2019). At most, a reduction of 80% of the outburst brightness can be seen in the case of KIC 9406652 (Gies et al 2013).…”

Section: Introductionmentioning

confidence: 95%

HO Puppis: Not a Be Star, but a Newly Confirmed IW And-type Star

Lee

et al. 2021

ApJ

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HO Puppis (HO Pup) was considered as a Be-star candidate based on its γ Cassiopeiae-type light curve, but lacked spectroscopic confirmation. Using distance measured from Gaia Data Release 2 and the spectral-energydistribution fit on broadband photometry, the Be-star nature of HO Pup is ruled out. Furthermore, based on the 28,700 photometric data points collected from various time-domain surveys and dedicated intensive-monitoring observations, the light curves of HO Pup closely resemble those of IW And-type stars (as pointed out by Kimura et al.), exhibiting characteristics such as a quasi-standstill phase, brightening, and dips. The light curve of HO Pup displays various variability timescales, including brightening cycles ranging from 23 to 61 days, variations with periods between 3.9 days and 50 minutes during the quasi-standstill phase, and a semiregular ∼14 day period for the dip events. We have also collected time-series spectra (with various spectral resolutions), in which Balmer emission lines and other spectral lines expected for an IW And-type star were detected (even though some of these lines were also expected to be present for Be stars). We detect Bowen fluorescence near the brightening phase, and that can be used to discriminate between IW And-type stars and Be stars. Finally, despite only observing for four nights, the polarization variation was detected, indicating that HO Pup has significant intrinsic polarization.

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“…Robertson et al ( 2018 ) propose a contrary view based on observ ational e vidence of UU Aqr that about half of the stunted outbursts coincided with increased hotspot emissions and hence higher Ṁ . Subsequently, Schlegel & Honeycutt ( 2019 ) studied an eclipsing nova-like (AC Cnc) and found that the stunted outbursts were eclipsed by the disc suggesting that either the outbursts originated on the facing hemisphere of the donor or were due to changes in the disc.…”

Section: Quasi-periodic Outburstsmentioning

confidence: 99%

ASAS J071404+7004.3 – a close, bright nova-like cataclysmic variable with gusty winds

Inight

Gänsicke

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Despite being bright (V ≃ 11.8) and nearby (d = 212 pc) ASAS J071404+7004.3 has only recently been identified as a nova-like cataclysmic variable. We present time-resolved optical spectroscopy obtained at the Isaac Newton and the Hiltner and McGraw-Hill Telescopes, together with Swift X-ray and ultraviolet observations. We combined these with TESS photometry and find a period of 3.28 h and a mass transfer rate of $4-9\times 10^{-9}\, {\rm{M_{\odot }\, yr}^{-1}}$. Historical photometry shows at least one low state establishing the system as a VY Scl star. Our high-cadence spectroscopy also revealed rapidly changing winds emanating from the accretion disc. We have modelled these using the Monte Carlo python code and shown that all the emission lines could emanate from the wind – which would explain the lack of double-peaked lines in such systems. In passing, we discuss the effect of variability on the position of cataclysmic variables in the Gaia Hertzsprung-Russell diagram.

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The K2 Light Curves and Stunted Outbursts of AC Cnc

Cited by 7 publications

References 28 publications

Thermal-viscous instability in tilted accretion disks: A possible application to IW Andromeda-type dwarf novae

Thermal-viscous instability in tilted accretion disks: A possible application to IW Andromeda-type dwarf novae

HO Puppis: Not a Be Star, but a Newly Confirmed IW And-type Star

ASAS J071404+7004.3 – a close, bright nova-like cataclysmic variable with gusty winds

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