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

Review of Cataclysmic Review of Cataclysmic Variables : Variables :

Unification model Unification model for various types of for various types of

variationsvariationsMakoto Uemura Makoto Uemura

(Kyoto University : VSNET (Kyoto University : VSNET team)team)

ContentsContents

Recent works of the VSNET teamRecent works of the VSNET team Various types of variations in CVsVarious types of variations in CVs Unification model for the CV Unification model for the CV

activityactivity To “see” accretion disksTo “see” accretion disks SummarySummary

Recent works 1 : GRB Recent works 1 : GRB 010222010222

Left : CCD images of GRB 010222 taken at Kyoto University (Rc=19.3). The right image is from DSS.

Black hole X-ray transient V4641 SBlack hole X-ray transient V4641 Sgrgr

WZ Sge outburst in 2001WZ Sge outburst in 2001

(VSNET)

Sub-groups of CVsSub-groups of CVs

NovaNova Dwarf novaDwarf nova

SS Cyg SS Cyg Z Cam Z Cam SU UMa SU UMa WZ Sge WZ Sge

Nova-like Nova-like variablesvariables RW TriRW Tri UX UMaUX UMa SW SexSW Sex VY SclVY Scl

Magnetic CVsMagnetic CVs Polar Polar Intermediate Intermediate

polarpolar

Dwarf nova U Gem Dwarf nova U Gem

6mag

1yr

“Outburst”

(VSNET)

Dwarf nova Z Cam Dwarf nova Z Cam

3mag

3mon

“Standstill”

(VSNET)

Dwarf nova SU UMa Dwarf nova SU UMa

3mag

1mon

Normal outburst

“Superoutburst”

(VSNET)

Superhumps in SU UMa Superhumps in SU UMa starsstars

(VSNET)

Nova-like variable UX Nova-like variable UX UMaUMa

2mag

1yr

(VSNET)

Characteristics of sub-Characteristics of sub-classesclasses SS Cyg : (normal) outburstSS Cyg : (normal) outburst Z Cam : standstill Z Cam : standstill SU UMa : superoutburst + SU UMa : superoutburst +

superhumpssuperhumps Nova-like variables : quasi-steadyNova-like variables : quasi-steady

Artist’s view of CVsArtist’s view of CVs

(Credit: K. Smale)

PPorb orb – Mv relation – Mv relation

Dwarf nova

Novalike

Z Cam

SS CygSU UMa

(Warner 1987)

Unification model of CVs : Unification model of CVs : 1. Thermal instability of 1. Thermal instability of accretion diskaccretion disk

Low temperature “Quiescence”

High temperature “Outburst”

Unification model of CVs :Unification model of CVs :2. Tidal instability model2. Tidal instability model

Psuperhump ~ 1.03 Porbital

(SPH simulation by Murray)

PPorb orb – Mv relation – Mv relation

Dwarf nova

Novalike

Z Cam

SS CygSU UMa

Thermal instability

Tidal instabilit

y

(Osaki 1996)

Observation of “disks”Observation of “disks”

Observation

Eclipse mapping

Examples of eclipse mapping: Examples of eclipse mapping: IY UMaIY UMa

Superoutburst on 2000 January

Early phase with fully-grown superhumps

Late phase with late superhumps

Examples of eclipse mapping: Examples of eclipse mapping: DV UMaDV UMa

Superoutburst Superoutburst on 1999 on 1999

DecemberDecember

Rapid Rapid evolution of evolution of an accretion an accretion disk during disk during the very early the very early phase of the phase of the superoutburssuperoutburstt

Summary Summary Various types of variations in CVs can basiVarious types of variations in CVs can basi

cally be interpreted with two instabilities wically be interpreted with two instabilities within accretion disks.thin accretion disks.

The eclipse mapping method is a strong toThe eclipse mapping method is a strong tool to study accretion disks. For investigatiol to study accretion disks. For investigation of continuous evolution of disks, multi-lon of continuous evolution of disks, multi-longitude observations are essential.ongitude observations are essential.

VSNET serves a number of information on VSNET serves a number of information on variable stars through e-mails, ftp, and wevariable stars through e-mails, ftp, and web. Let’s enjoy the world of VSNET ! b. Let’s enjoy the world of VSNET ! (http://v(http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/index.html)snet.kusastro.kyoto-u.ac.jp/vsnet/index.html)