Spectroscopy of helium dwarf novae in AM CVn systems

矮新星爆发被认为是CV系统中圆盘的不稳定性导致主白矮星的质量吸积率提高。我们拟对AM - CVn双星系统中的三颗氦矮新星进行光谱观测。AM CVn系统的供体恒星是一颗富氦（半）简并星，因此吸积盘以氦为主。因此，突出行为是相当不同的。我们的目标的爆发周期是几天。为了描述吸积盘的物理状态，我们想研究光谱变异性作为相位的函数。光谱将用非lte吸积盘模型进行分析，该模型可以确定质量吸积率和化学成分等。

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.