Publication detail

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae

Kato, T. et al.

Original Title

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae

Type

journal article in Web of Science

Language

English

Original Abstract

We systematically surveyed period variations of superhumps in SU UMa-type dwarf novae based on newly obtained data and past publications. In many systems, the evolution of the superhump period is found to be composed of three distinct stages: an early evolutionary stage with a longer superhump period, a middle stage with systematically varying periods, and a final stage with a shorter, stable superhump period. During the middle stage, many systems with superhump periods of less than 0.08 d show positive period derivatives. We present observational characteristics of these stages and give greatly improved statistics. Contrary to an earlier claim, we found no clear evidence for a variation of period derivatives among different superoutbursts of the same object. We present an interpretation that the lengthening of the superhump period is a result of the outward propagation of an eccentricity wave, which is limited by the radius near the tidal truncation. We interpret that late-stage superhumps are rejuvenated excitation of a 3:1 resonance when superhumps in the outer disk are effectively quenched. The general behavior of the period variation, particularly in systems with short orbital periods, appears to follow a scenario proposed in Kato, Maehara, and Monard (2008, PASJ, 60, L23). We also present an observational summary of WZ Sge-type dwarf novae. Many of them have shown long-enduring superhumps during a post-superoutburst stage having longer periods than those during the main superoutburst. The period derivatives in WZ Sge-type dwarf novae are found to be strongly correlated with the fractional superhump excess, or consequently with the mass ratio. WZ Sge-type dwarf novae with a long-lasting rebrightening or with multiple rebrightenings tend to have smaller period derivatives, and are excellent candidates for those systems around or after the period minimum of evolution of cataclysmic variables.

Keywords

accretion, accretion disks; stars: dwarf novae; stars: novae, cataclysmic variables

Authors

Kato, T.; et al.

RIV year

2009

Released

15. 12. 2009

Publisher

C/O NATIONAL ASTRONOMICAL OBSERVATORY, 2-21-1 OSAWA, MITAKA-SHI, TOKYO, 181-8588, JAPAN

Location

Tokyo

ISBN

0004-6264

Periodical

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN

Year of study

61

Number

2

State

Japan

Pages from

395

Pages to

616

Pages count

221

BibTex

@article{BUT49458,
  author="Kato, T. and et al.",
  title="Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae",
  journal="PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN",
  year="2009",
  volume="61",
  number="2",
  pages="395--616",
  issn="0004-6264"
}