Review of Cataclysmic Variables Unification model for various
Review of Cataclysmic Variables : Unification model for various types of variations Makoto Uemura (Kyoto University : VSNET team)
Contents Recent works of the VSNET team n Various types of variations in CVs n Unification model for the CV activity n To “see” accretion disks n Summary n
Recent works 1 : GRB 010222 Left : CCD images of GRB 010222 taken at Kyoto University (Rc=19. 3). The right image is from DSS.
Black hole X-ray transient V 4641 Sgr
WZ Sge outburst in 2001 (VSNET)
Sub-groups of CVs Nova n Dwarf nova n SS Cyg n Z Cam n SU UMa n WZ Sge n Nova-like variables RW Tri n UX UMa n SW Sex n VY Scl n n n Magnetic CVs Polar n Intermediate polar n
Dwarf nova U Gem 1 yr “Outburst” 6 mag (VSNET)
Dwarf nova Z Cam 3 mon “Standstill” 3 mag (VSNET)
Dwarf nova SU UMa 1 mon “Superoutburst” Normal outburst 3 mag (VSNET)
Superhumps in SU UMa stars (VSNET)
Nova-like variable UX UMa 1 yr 2 mag (VSNET)
Characteristics of sub-classes SS Cyg : (normal) outburst n Z Cam : standstill n SU UMa : superoutburst + superhumps n Nova-like variables : quasi-steady n
Artist’s view of CVs (Credit: K. Smale)
Porb – Mv relation Novalike Z Cam SU UMa SS Cyg Dwarf nova (Warner 1987)
Unification model of CVs : 1. Thermal instability of accretion disk High temperature “Outburst” Low temperature “Quiescence”
Unification model of CVs : 2. Tidal instability model Psuperhump ~ 1. 03 Porbital (SPH simulation by Murray)
Porb – Mv relation Novalike Tidal instability Z Cam Thermal instability SU UMa SS Cyg Dwarf nova (Osaki 1996)
Observation of “disks” Observation Eclipse mapping
Examples of eclipse mapping: IY UMa Superoutburst on 2000 January Early phase with fullygrown superhumps Late phase with late superhumps
Examples of eclipse mapping: DV UMa Superoutburst on 1999 December Rapid evolution of an accretion disk during the very early phase of the superoutburst
Summary Various types of variations in CVs can basically be interpreted with two instabilities within accretion disks. n The eclipse mapping method is a strong tool to study accretion disks. For investigation of continuous evolution of disks, multilongitude observations are essential. n VSNET serves a number of information on variable stars through e-mails, ftp, and web. Let’s enjoy the world of VSNET ! n (http: //vsnet. kusastro. kyoto-u. ac. jp/vsnet/index. html)
- Slides: 26