Study of outbursts in large accretion discs

Recurrent novae (RNe) are binary systems that undergo repeated ordinary nova eruptions. The reason for our interest in them is their possible relevance to the search for progenitors of Supernovae Ia. RN can be considered as a candidate for SN Ia progenitor - it is probable that during RN outbursts not all accreted matter is ejected. It is the opposite of Classical Novae outbursts, during which all accreted matter is ejected from the surface of the star. Although it is established that Recurrent Novae outbursts are thermonuclear, it is possible that the viscous-thermal instability may also cause outbursts in these systems.We calculated the significant majority of vertical structure grid for expected RS Oph accretion disc parameters. The most recent result is 5,581,729 points out of 6,000,000 (giving 93,03%) vertical structure grid calculated. Still, there are regions full of unconverged points, especially in the outer edge. We also computed S-curves (solutions of thermal equilibrium equation in the disc) for the region of interest.During calculations we have been faced with serious numerical problems, which hindered the progress of the work. As a result, we proposed a new procedure. Also we created set of scripts for this purpose. The new procedure is less time-consuming, improves efficiency of algorithm and makes the procedure more automatic. The set contains few diagnostic scripts which quickly show where the vertical structure code diverges.

Recurrent novae (RNe) are binary systems that undergo repeated ordinary nova eruptions. The reason for our interest in them is their possible relevance to the search for progenitors of Supernovae Ia. RN can be considered as a candidate for SN Ia progenitor - it is probable that during RN outbursts not all accreted matter is ejected. It is the opposite of Classical Novae outbursts, during which all accreted matter is ejected from the surface of the star. Although it is established that Recurrent Novae outbursts are thermonuclear, it is possible that the viscous-thermal instability may also cause outbursts in these systems.We calculated the significant majority of vertical structure grid for expected RS Oph accretion disc parameters. The most recent result is 5,581,729 points out of 6,000,000 (giving 93,03%) vertical structure grid calculated. Still, there are regions full of unconverged points, especially in the outer edge. We also computed S-curves (solutions of thermal equilibrium equation in the disc) for the region of interest.During calculations we have been faced with serious numerical problems, which hindered the progress of the work. As a result, we proposed a new procedure. Also we created set of scripts for this purpose. The new procedure is less time-consuming, improves efficiency of algorithm and makes the procedure more automatic. The set contains few diagnostic scripts which quickly show where the vertical structure code diverges.