Thermal-Viscous Instability in Tilted Accretion Disks: A Possible Application to IW And-Type Dwarf Novae

Kimura, M.

doi:10.1007/978-981-15-8912-6_5

Cited by 2 publications

(4 citation statements)

References 30 publications

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“…These phenomena are likely the same as low-amplitude outbursts recorded in IX Vel. Kimura et al (2020) performed numerical simulations of dwarf nova outbursts (both in tilted and non-tilted disks) based on the thermal-viscous instability model (the simulation scheme was based on Ichikawa and Osaki 1992). In their simulations (figure 18 in Kimura et al 2020), tilted disks are prone to thermal instability even under the condition of the mass-transfer rate high enough to keep the entire disk hot in a non-tilted disk.…”

Section: Discussionmentioning

confidence: 99%

“…Kimura et al (2020) performed numerical simulations of dwarf nova outbursts (both in tilted and non-tilted disks) based on the thermal-viscous instability model (the simulation scheme was based on Ichikawa and Osaki 1992). In their simulations (figure 18 in Kimura et al 2020), tilted disks are prone to thermal instability even under the condition of the mass-transfer rate high enough to keep the entire disk hot in a non-tilted disk. Their resultant light curve looks similar to that of IX Vel and it would be worth studying whether there is a signature of a disk tilt in this system.…”

Section: Discussionmentioning

confidence: 99%

“…Their resultant light curve looks similar to that of IX Vel and it would be worth studying whether there is a signature of a disk tilt in this system. The present observational knowledge of the behavior of the accretion disk near the border of the thermal instability might also be helpful in understanding the unusual behavior of IW And stars (Simonsen 2011;Hameury and Lasota 2014;Kato 2019;Kimura et al 2020), which are also considered to have accretion disks near the border of the thermal instability.…”

Section: Discussionmentioning

confidence: 99%

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Study of the low-amplitude Z Cam star IX Vel

Katô¹

2021

Preprint

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IX Vel has been considered as one of the prototypical novalike cataclysmic variables with thermally stable accretion disks. Using All-Sky Automated Survey (ASAS-3) and All-Sky Automated Survey for Supernovae (ASAS-SN) observations, I found that IX Vel is a low-amplitude dwarf nova showing standstills. This object has been re-classified as a Z Cam-type dwarf nova. This conclusion is consistent with the mass-transfer rate using the Gaia parallax which places the object near the lower limit of the thermal stability. Using twodimensional Least Absolute Shrinkage and Selection Operator (Lasso), I found that the cycle lengths of dwarf nova outbursts varied between 13 and 20 d. Analysis of the ASAS-3 data suggested that the cycle lengths are shorter and the amplitudes are smaller when the system is bright. Standstills occurred when the system was bright. These results support the idea that a subtle variation in the mass-transfer rate from the secondary causes transitions between outbursting state and standstills in Z Cam stars.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Study of the low-amplitude Z Cam star IX Vel

Katô¹

2021

Preprint

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“…Accretion disks of the dwarf novae of this type are considered to be near the thermal stability (see e.g. Kimura et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Orbital period of the IW And-type star ST Cha

Katô¹,

Kojiguchi²

2021

Preprint

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We analyzed TESS data of the IW And-type dwarf nova ST Cha during ordinary dwarf nova states. We have identified an orbital period of 0.285360(1) d. The object was reported to be eclipsing in the past using the data obtained in the 1970s, which is not in agreement with the present data. Despite the constant mean brightness, the strength of the orbital signal varied significantly, suggesting that the strength of the orbital signal does not always reflect the mass-transfer rate. During an outburst with a shoulder, we did not find evidence of humps recurring with a period longer than the orbital period which were recorded in V363 Lyr. This finding strengthens the idea that V363 Lyr is an unusual object. We found that the strength of the orbital signal increased after an outburst with a shoulder. This outburst may have changed the state of the disk and the hot spot became more apparent. Such a change in the disk may have triggered a transition from an ordinary dwarf nova-type state to an IW And-type state and this possibility would require further examination.

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Thermal-Viscous Instability in Tilted Accretion Disks: A Possible Application to IW And-Type Dwarf Novae

Cited by 2 publications

References 30 publications

Study of the low-amplitude Z Cam star IX Vel

Study of the low-amplitude Z Cam star IX Vel

Orbital period of the IW And-type star ST Cha

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