Spectroscopy of helium dwarf novae in AM CVn systems

• Applicant: Dr. Thorsten Nagel
• Subject Area: Astrophysics and Astronomy
• Term: from 2006 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 27336705

Dwarf nova outbursts are assumed to be disc instabilities in CV systems leading to enhanced mass-accretion rates onto the primary white dwarf. We propose to perform spectroscopic observations of three helium dwarf novae in AM CVn binary systems. The donor star in AM CVn systems is a helium-rich (semi-) degenerate star, hence, the accretion disc is dominated by helium in contrast to other CVs. Therefore the outburst behaviour is rather different. The outburst cycle times of our targets are of the order of days. We want to study the spectral variability as a function of phase in order to characterize the physical states of accretion discs. The spectra will be analysed with non-LTE accretion disc models, which allow to determine, e.g., mass-accretion rate and chemical composition.

• DFG Programme: Research Grants