X-ray Observations of Novae
Joachim Krautter

Nova explosions are the third most violent explosion that can occur in a galaxy, exceeded only by supernova explosions and gamma-ray bursts. The cause of a nova outburst is a thermonuclear runaway which occurs in the accreted hydrogen-rich layer near the surface of a white dwarf in a close binary system. Novae have received particular attention since they are hot candidates (in particular the Recurrent Novae) for the precursors of SN Ia. X-ray observations have turned out to be the most powerful tool to study the hot phases in a nova outburst, where the essential physical processes are going on. X-ray observations allow to study the hot white dwarf and shocks in the expanding envelope, to derive temperatures and luminosities and to carry out plasma diagnostics of the line emitting regions. After a general overview of the nova outburst and its physical mechanisms, X-ray observations which gave totally new insights into the nova outburst will be discussed.