Title : Impact of mass transfer rate on the behaviour of cataclysmics

Abstract

The transfer of mass between the two stellar components via an accretion disc, a characteristic of cataclysmic variables (CVs), gives rise to various intriguing astrophysical phenomena such as nova, dwarf nova, etc. It appears that the rate at which this transfer of mass takes place plays a significant role in the dwarf nova cycle and the behaviour of cataclysmics in general. Depending on it, a CV may show characteristics of a dwarf nova with semi-regular outbursts or a novalike variable. The canonical evolution model of cataclysmics suggests that different mechanisms are responsible for driving the mass transfer above and below the period gap (2 hr ≲ Porb ≲ 3 hr). However, the reduction and enhancement in the mass transfer rate (e.g. novalikes) and the underlying causes are still not understood well. In this talk, I will discuss the response of a cataclysmic system to different mass transfer rates. I will also present the calculation of mass transfer rate for the long period dwarf nova system V1948 Cyg and discuss how the results accord with the disc instability model.

Title : Impact-induced textures and phase transformations in shocked Indian meteorites.

Abstract

Hyper-velocity impact between planetary bodies induces high-pressure and high-temperature conditions triggering polymorphic transformation within the impacted materials. Moreover, such impacts lead to the fragmentation of the impactor with fragments dislodged in all directions. Some of these fragments eventually fall on Earth as shocked meteorites. Here, I will present my analysis of shocked Indian meteorites. I will discuss different high-pressure phases and shock-induced textures present in these meteorites and their formation conditions.