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Abstract: By various methods, we obtained L$ {disk}$ $\sim$ 70 L$ {\odot}$ and$\dot{M}$ $\sim$1.1 $\times$ 10$^{-8}$ M$ {\odot}$yr$^{-1}$. These values wereabout twice as high in the pre-1966-outburst epoch. This allowed the firstdirect estimate of the total mass accreted before outburst,M$ {accr}$=$\dot{M} {pre-OB}$ $\cdot \Delta$t, and its comparison with thecritical ignition mass M$ {ign}$. We found M$ {accr}$ and M$ {ign}$ to be inperfect agreement with a value close to 5 $\times$ 10$^{-7}$M$ {\odot}$ forM$ 1$ $\sim$ 1.37 M$ {\odot}$, which provides a confirmation of thethermonuclear runaway theory. The comparison of the observed parameters of theeruption phase, with the corresponding values in the grid of models by Yaronand collaborators, provides satisfactory agreement for values of M$ 1$ close to1.35 M$ {\odot}$ and log$\dot{M}$ between -8.0 and -7.0, but the observed valueof the decay time t$ 3$ is higher than expected. The long duration of theoptically thick phase during the recorded outbursts of T Pyx, a spectroscopicbehavior typical of classical novae, and the persistence of P Cyg profiles,constrains the ejected mass M$ {ign}$ to within 10$^{-5}$ - 10$^{-4}$M$ {\odot}$. Therefore, T Pyx ejects far more material than it has accreted,and the mass of the white dwarf will not increase to the Chandrasekhar limit asgenerally believed in recurrent novae. A detailed study based on the UV dataexcludes the possibility that T Pyx belongs to the class of the supersoft X-raysources, as has been postulated. XMM-NEWTON observations have revealed a weak,hard source and confirmed this interpretation.



Author: P. Selvelli, A. Cassatella, R. Gilmozzi, R. Gonzalez-Riestra

Source: https://arxiv.org/







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