1993 Fiscal Year Final Research Report Summary
Unified Model of Outbursts in Dwarf Novae
| Project/Area Number |
04640267
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OSAKI Yoji The University of Tokyo, Graduate School of Science : Professor, 大学院・理学系研究科, 教授 (30011547)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBAHASHI Hiromoto The University of Tokyo, Graduate School of Science : Associate Professor, 大学院・理学系研究科, 助教授 (30126081)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Cataclysmic Variables / Accretion Disk / Dwarf Novae / SU Ursa Majoris Stars / WZ Sagittae Stars / Stability / Superoutburst |
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| Research Abstract |
Dwarf novae are eruptive variables showing repetitive outbursts of amplitudes of 2-6 magnitude. There are three sub-classes in dwarf novae : the U Gem-type showing only the ordinary outbursts, the Z Cam-type showing occasional standstill, and the SU UMa-type showing superoutbursts. The main purpose of this research is to examine whether or not we can explain rich variety of outburst phenomena in dwarf novae by a unified paradigm : the so-called disk instability model. To this end, we have made detailed numerical simulations of the superoutburst phenomenon of SU UMa stars by the combined mechanism of the thermal and tidal instabilities of accretion disks. It has been found that the superoutburst cycle of SU UMa stars can be successfully reproduced by this model. We have formulated the tidal eccentric instability of an accretion disk as an eigenvalue problem of the oscillation of the one-armed mode in the accretion disk and we have examined the eigenvalue and eigenfunction of this mode both numerically and analytically. The disk instability model for SU UMa-type dwarf novae is examined in relation to the WZ Sge-type dwarf novae which exhibit only superoutbursts but apparently no normal outburst. A particular case of the most extreme star of WZ Sge itself is discussed and it is suggested as an extreme case of very low viscosity in quiescence and of rather low mass transfer rate from the secondary.
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Research Products
(12 results)
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[Publications] Duvall, T.L., Jr., Jefferies, S.M., Harvey, J.W., Osaki, Y., & Pomerantz, M.A.: ""Asymmetries of Solar Oscillation Line Profiles"" ApJ. 410. 829-836 (1993)
Description
「研究成果報告書概要(欧文)」より
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