Common Envelope and the Binding Energy Consideration

We report the results of our study on the common-envelope phase of the cataclysmic variables. We are investigating the role of additional energies, such as recombination energy and internal energy, in expelling the envelope of the primary star. In this work, we use the TWIN stellar evolution code which can evolve both stars in binary simultaneously. We analysed the energies involved by considering the binding energy of the core at the onset of the common envelope phase. The core of the primary is calculated using the hydrogen-exhausted layer with 10% hydrogen fraction. Our preliminary result shows that the internal energy plays a significant role while the recombination energy has only a small contribution to the energy budget of the cataclysmic variable evolution.