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arXiv 2507.22331astro-ph.SRastro-ph.HE
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新星的轨道周期变化

The orbital period changes for novae

Wenshi Tang, Xiangdong Li, Bo Wang

AI总结:

针对激变变星轨道周期变化观测与标准演化理论冲突的问题,研究通过建模三种新星爆发物质损失机制,发现双星驱动物质损失可解释大部分普通激变变星的观测,长周期演化伴星系统可能需Frank喷流机制补充。

摘要:

激变变星(Cataclysmic variable,简称CVs)是密近相互作用双星系统,其中白矮星从低质量主序伴星吸积物质。由于较低的物质转移率,CVs会经历新星爆发。在CV演化的标准理论中,新星爆发期间抛出的物质被假定以快速、各向同性的光学厚风的形式离开系统,该理论预测新星只会导致轨道周期的正向变化(即轨道膨胀),也就是ΔP为正。此外,角动量损失(磁制动和引力辐射)仅能预测CVs轨道周期的长期稳定衰减,即Ṗ为负。有趣的是,一项持续30多年的观测显示,CVs的ΔP和Ṗ均存在正负两种取值,这与标准演化模式存在强烈冲突。不过,由于观测时间尺度较短,无法排除这些观测结果源自新星爆发引发的短期现象的可能性。在本文中,我们对瞬时新星爆发对CVs演化的影响进行了建模,考虑了与新星爆发物质损失相关的三种机制,包括快速风、Frank喷流以及双星驱动的物质损失。通过假定观测到的ΔP和Ṗ由短期现象主导,我们的结果表明,双星驱动的物质损失几乎可以解释所有普通CVs的观测结果。不过,部分拥有演化后伴星的长周期CVs可能需要用Frank喷流机制来解释。

英文摘要:

Cataclysmic variable (CVs) are close interacting binaries in which a white dwarf accretes materials from a low mass main sequence companion. CVs can experience nova eruptions due to low mass transfer rates. In the standard theory of CV evolution, the ejected materials during nova eruptions are assumed to leave the system in the form of fast, isotropic, optically thick winds, which predicts that novae only result in positive variation (expansion) of orbital period (i.e. positive $ΔP$). In addition, the angular momentum losses (magnetic braking and gravitational radiation) only predicts a steady long-term decay in the orbital period of CVs, i.e. $\dot P$ is negative. Interestingly, an observation lasting over 30 years reveals positive and negative values for both $ΔP$ and $\dot P$ in CVs, strongly conflicting with the standard evolutionary patterns. However, it cannot be excluded that these observations originate from short-term phenomena caused by nova eruptions because of a short timescale of observations. In this paper, we model the effect of instantaneous nova eruptions on the evolution of CVs, considering three mechanisms associated with mass loss in nova eruptions, including fast wind, Frank jet and binary-driven mass loss. By assuming that the observed $ΔP$ and $\dot P$ are dominated by short-term phenomena, our results show that the binary-driven mass loss can explain almost all of the observations of normal CVs. However, the Frank jet may be needed for some of long-period CVs with evolved companions.

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