The Recurrent Nova RS Ophiuchiby Doris Folini and Rolf Walder
Quiescient Accretion Phase
Movie of Nova Outburst
IntroductionRS Ophiuchi is a recurrent nova with a period of about 22 years, timescale, consisting of a wind accreting binary system with a white dwarf (WD) very close to the Chandrasekhar limit and a red giant star (RG). The system is considered a prime candidate to evolve into an SNIa. For its most recent outbursts in 1985 and 2006, exquisite multiwavelength observational data are available.
We present a three dimensional hydrodynamic simulation of the quiescent accretion and the subsequent explosive phase. In combination with recent multi-cycle nova models, our results suggests that the WD in RS Oph will increase in mass. Several speculative outcomes then seem plausible. The WD may reach the Chandrasekhar limit and explode as an SN Ia. Alternatively, the mass loss of the RG could result in a smaller Roch volume, a common envelope phase, and a narrow WD + WD system. Angular momentum loss due to graviational wave emission could trigger the merger of the two WDs and -- perhaps -- an SN Ia via the double degenerate scenario.
Quiescient Accretion PhaseThe computed circumstellar mass distribution in the quiescent phase is highly structured with a mass enhancement in the orbital plane of about a factor of 2 as compared to the poleward directions. For vRG = 20 km/s and for nearly isothermal flows, we derive a mass transfer rate to the WD of 10% of the mass loss of the RG. For an RG mass loss of 10-7 solar masse per year, we found the orbit of the system to decay by 3% per million years. With the derived mass transfer rate, multi-cycle nova models provide a qualitatively correct recurrence time, amplitude, and fastness of the nova.
Nova OutburstThe simulated nova remnant evolves aspherically, propagating faster toward the poles. The shock velocities derived from the simulations are in agreement with those derived from observations.
Movie of Nova OutburstThe movie shows the relaxed flow in density during the accretion phase and the subsequent nova blast wave. The big panel on the left shows the orbital plane on a scale of 7*1014 cm a side. The right panels show the full domain, 1015 cm a side, in the orbital plane (upper panel) and normal to the orbital plane (lower panel). The time lapse covers a period of 21 days. The same logarithmic colour map applies to all three panels and covers the density range between 10-18g/cm3 and 10-13 g/cm3.
Available as avi format (9.5MB) or quicktime format (9.9MB).
ReferencesR. Walder and D. Folini and S. N. Shore
3D simulations of RS Oph: from accretion to nova blast
Astronomy and Astrophysics Letter, in press
(Available as a 1.0MB gzipped pdf-file)
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Doris Folini and Rolf Walder
Last Update: April 16, 2008