Multiwavelength modelling the SED of supersoft X-ray sources. II. RS Ophiuchi: From the explosion to the SSS phase

Abstract

RS Oph is a recurrent symbiotic nova that undergoes nova-like outbursts on a time scale of 20 years. Its two last eruptions (1985 and 2006) were subject of intensive multiwavelengths observational campaign from the X-rays to the radio. This contribution aims to determine physical parameters and the ionization structure of the nova from its explosion to the first emergence of the supersoft X-rays (day 26) by using the method of multiwavelength modelling the SED. From the very beginning of the eruption, the model SED revealed the presence of both a strong stellar and nebular component of radiation in the spectrum. During the first 4 days, the nova evinced a biconical ionization structure. The $\sim 8200$ K warm and 160 - 200 R$_{\odot}$ extended pseudo-photosphere encompassed the white dwarf (WD) around its equator to the latitude $>40^{\circ}$. The remaining space around the WD's poles was ionized, producing a strong nebular continuum with the emission measure $EM \sim 2.3 \times 10^{62}$ cm$^{-3}$ via the fast wind from the WD. The luminosity of the burning WD was highly super-Eddington for the whole investigated period. The wind mass loss at rates of $10^{-4} - 10^{-5}$ M$_{\odot}$yr$^{-1}$ and the presence of jets suggest an accretion throughout a disk at a high rate, which can help to sustain the super-Eddington luminosity of the accretor for a long time.