RS Oph :RS Oph :Unstable Disk Unstable Disk

ModelModelXu XiaojieXu Xiaojie

2009/05/202009/05/20reference : King & Pringle, arXiv: 0905.0637reference : King & Pringle, arXiv: 0905.0637

Dewi & Tauris, 2000, A&A 360, Dewi & Tauris, 2000, A&A 360, 10431043

ABCs of RS OphABCs of RS Oph P=453.5 d, evolved giant companion P=453.5 d, evolved giant companion

(CVs have main sequence companion)(CVs have main sequence companion) Nova, Recurrent cycle ~ 21yrs Nova, Recurrent cycle ~ 21yrs

(1898--2006), relatively short;(1898--2006), relatively short; Bursting model:Bursting model:

1. unstable H burning on a massive 1. unstable H burning on a massive WD (~1.35M_s) surface, possible SN WD (~1.35M_s) surface, possible SN Ia progenitorIa progenitor

2. unstable accretion disk2. unstable accretion disk varying varying accretion rate, no heavy WD neededaccretion rate, no heavy WD needed

Observational Properties Observational Properties

Mixing of accreted matter and those Mixing of accreted matter and those of WD can cause WD matter lost of WD can cause WD matter lost during flashes: C, N, O, Ne, but no during flashes: C, N, O, Ne, but no significant sign for RS Ophsignificant sign for RS Oph

Well-collimated jets produced during Well-collimated jets produced during the outburst in 2006the outburst in 2006

Sources harboring jets ( quasars, Sources harboring jets ( quasars, microquasars, some X-ray binaries) microquasars, some X-ray binaries) have following in common:have following in common:disk accretion, high jet velocity, 10% disk accretion, high jet velocity, 10% accreted matter expelled, accreted matter expelled,

Theoretical DifficultiesTheoretical Difficulties

For nuclear bursting, to accumulate matter For nuclear bursting, to accumulate matter for outburst, accretion rate requiresfor outburst, accretion rate requires

While RS Oph lack of X-ray during While RS Oph lack of X-ray during quiescencequiescence

Matter in disk easily blow away Matter in disk easily blow away no jets no jets Nuclear burning hard to produce jetsNuclear burning hard to produce jets

JetsJets

Disk ModelDisk Model

P=453.5d P=453.5d a ~1.4AU a ~1.4AU Stable accretion requires M_2< M_1Stable accretion requires M_2< M_1 Stellar wind accretion ruled outStellar wind accretion ruled out RLOF forms an accretion disk, with RLOF forms an accretion disk, with

outer radius ~ 70% WD roche lobe, size outer radius ~ 70% WD roche lobe, size ~0.5a ~ 0.7AU ~ 10^12cm~0.5a ~ 0.7AU ~ 10^12cm

T of outer accretion disk less than T of outer accretion disk less than 6500K6500K

Disk unstableDisk unstable

Unstable Disk Unstable Disk

EquationsEquations

Equations IIEquations II

Irradiated DiskIrradiated Disk

Pros of Unstable DiskPros of Unstable Disk

Explanation of rising and decaying Explanation of rising and decaying of outburstof outburst

JetsJets Mass transfer rateMass transfer rate Large accretion diskLarge accretion disk Dynamical determination of the WD Dynamical determination of the WD

mass?mass?

Classic Evolution PathClassic Evolution Path

Classic Evolution Path IIClassic Evolution Path II

**2 mass less than WD mass ~~*2 accreted 2 mass less than WD mass ~~*2 accreted little matter~~ CE favoredlittle matter~~ CE favored

Orbital shrinking during CE, why P~450dOrbital shrinking during CE, why P~450d

CE?CE?

Less energy dissipation on CE phaseLess energy dissipation on CE phase Binding energy of the envelope Binding energy of the envelope

Total change in orbital energyTotal change in orbital energy

Energy converting efficiencyEnergy converting efficiency

Ejection & Binding Ejection & Binding ParameterParameter

Final separationFinal separation

The actual binding energyThe actual binding energy

Dewi’s CalculationDewi’s Calculation

Final SeperationFinal Seperation

Lambda for 3 Solar Mass Lambda for 3 Solar Mass StarStar

Happy Happy Birthday, Birthday,

NJUNJU