1. Makoto Uemura (Kyoto University : VSNET team)
Review of Cataclysmic Variables : Unification model for various types of variations
Makoto Uemura
(Kyoto University : VSNET team)

2. Contents Recent works of the VSNET team
Various types of variations in CVs
Unification model for the CV activity
To “see” accretion disks
Summary

3. Recent works 1 : GRB
Left : CCD images of GRB taken at Kyoto University (Rc=19.3). The right image is from DSS.

8. Black hole X-ray transient V4641 Sgr

9. WZ Sge outburst in 2001
(VSNET)

11. Sub-groups of CVs Nova Dwarf nova Nova-like variables Magnetic CVs
SS Cyg
Z Cam
SU UMa
WZ Sge
Nova-like variables
RW Tri
UX UMa
SW Sex
VY Scl
Magnetic CVs
Polar
Intermediate polar

12. Dwarf nova U Gem
1yr
“Outburst”
6mag
(VSNET)

13. Dwarf nova Z Cam
3mon
“Standstill”
3mag
(VSNET)

14. Dwarf nova SU UMa
1mon
“Superoutburst”
Normal outburst
3mag
(VSNET)

15. Superhumps in SU UMa stars
(VSNET)

16. Nova-like variable UX UMa
1yr
2mag
(VSNET)

17. Characteristics of sub-classes
SS Cyg : (normal) outburst
Z Cam : standstill
SU UMa : superoutburst + superhumps
Nova-like variables : quasi-steady

18. Artist’s view of CVs
(Credit: K. Smale)

19. Porb – Mv relation Novalike Dwarf nova Z Cam SS Cyg SU UMa
(Warner 1987)

20. Unification model of CVs : 1. Thermal instability of accretion disk
High temperature “Outburst”
Low temperature “Quiescence”

21. Unification model of CVs : 2. Tidal instability model
Psuperhump ~ 1.03 Porbital
(SPH simulation by Murray)

22. Porb – Mv relation Tidal instability Thermal instability Novalike
Z Cam
Thermal instability
SS Cyg
SU UMa
Dwarf nova
(Osaki 1996)

23. Observation of “disks”
Eclipse mapping

24. Examples of eclipse mapping: IY UMa
Superoutburst on 2000 January
Early phase with fully-grown superhumps
Late phase with late superhumps

25. Examples of eclipse mapping: DV UMa
Superoutburst on 1999 December
Rapid evolution of an accretion disk during the very early phase of the superoutburst

26. Summary
Various types of variations in CVs can basically be interpreted with two instabilities within accretion disks.
The eclipse mapping method is a strong tool to study accretion disks. For investigation of continuous evolution of disks, multi-longitude observations are essential.
VSNET serves a number of information on variable stars through s, ftp, and web. Let’s enjoy the world of VSNET ! (