| With observing missions like the Rossi X-ray Timing Explorer (RXTE), BeppoSAX, XMM-Newton and Chandra many thermonuclear activities on neutron stars have been observed, especially thermonuclear X-ray bursts on accreting neutron stars. Aside from frequent short type I X-ray bursts, rare and very long enduring high energetic bursts, the so-called superbursts, have been found. The large total released energy during a superburst indicates a larger ignition depth and higher ignition temperatures than it is the case for type I bursts. These ignition conditions lead to the conclusion, that unstable carbon burning triggers the thermonuclear runaway for the superburst.;This work focusses on the carbon plasma layer and its nuclear fusion stability. With numerical simulations a stability analysis of the layer has been performed, in order to find precise conditions for unstable ignitions. The numerical model used in this thesis combines a full reaction network with a complex number perturbation stability analysis, in which effects of temperature, energy flux, composition and accretion rate on the stability were examined. Furthermore, different burning regimes in the carbon burning process have been investigated in order to determine the nature of the explosion as well as the exact ignition depth. For a few sets of parameters burning oscillations were investigated. For the neutron star KS 1731-260 the stability analysis was used to determine the chemical composition of the carbon burning layer. |
