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arXiv 1009.5367astro-ph.SR
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V344类星体的Kepler光变曲线:热粘性极限环不稳定性的约束

The Kepler Light Curve of V344 Lyrae: Constraining the Thermal-Viscous Limit Cycle Instability

J. K. Cannizzo, M. D. Still, S. B. Howell, M. A. Wood, A. P. Smale

摘要:

我们基于吸积盘极限环模型对开普勒拍摄的短周期SU UMa型矮新星V344 Lyr的270 d光变曲线进行了时间相关建模。前所未有的精度和节奏(1分钟)远远超过了长期光曲线的一般可用性。这些数据包括两次超级爆发和17次正常爆发(即,短)爆发。超级爆发的主要衰变几乎是完全指数的,以~12 d/mag的速率衰变,而正常爆发的衰变速度更快,呈现出比指数更快的形状。我们的模拟使用的基本吸积盘极限环可以产生的V344天琴座光变曲线的主要特征,包括峰值爆发亮度。然而,我们的模型光变曲线存在明显的不足:(1)我们计算的上升时间,无论是正常爆发还是超爆发,都太快了。(2)超级爆发太短了。(3)在超级爆发上升过程中的肩部比观测到的超级爆发中的肩部有更多的结构,并且速度太慢,约占总粘性平台的三分之一到一半,而不是观测到的约10%。然而,我们研究的其中一种alpha_{cold} -> alpha_{hot}插值方案(一种物理激发的方案)确实产生了较长的超爆发,具有适当的短的、结构较少的肩部。

英文摘要:

We present time dependent modeling based on the accretion disk limit cycle model for a 270 d light curve of the short period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long term light curves. The data encompass two superoutbursts and 17 normal (i.e., short) outbursts. The main decay of the superoutbursts is nearly perfectly exponential, decaying at a rate ~12 d/mag, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. Our modeling using the basic accretion disk limit cycle can produce the main features of the V344 Lyr light curve, including the peak outburst brightness. Nevertheless there are obvious deficiencies in our model light curves: (1) The rise times we calculate, both for the normal and superoutbursts, are too fast. (2) The superoutbursts are too short. (3) The shoulders on the rise to superoutburst have more structure than the shoulder in the observed superoutburst and are too slow, comprising about a third to half of the total viscous plateau, rather than the ~10% observed. However, one of the alpha_{cold} -> alpha_{hot} interpolation schemes we investigate (one that is physically motivated) does yield longer superoutbursts with suitably short, less structured shoulders.

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