论文标题
Dy Pegasi：二进制系统中的SX腓尼基星，带有进化的伴侣
DY Pegasi: An SX Phoenicis Star in a Binary System with an Evolved Companion
论文作者
论文摘要
在这项工作中，收集了来自美国可变星观察者协会的光度数据，并在SX腓尼基星Dy Pegasi（DY PEG）上分析。从频率分析中，我们获得三个独立频率：$ f_0 = 13.71249 \ \ rm { $ f_0 $和$ f_1 $分别是径向基本模式和第一个散色模式，而第一次检测到$ f_2 $，应属于非自由模式。 $ o-o-c $最大光的图表表明，dy peg具有周期变化率$（1/p_0）（\ mathrm {d} p_0/\ mathrm {d} t）= - （5.87 \ pm 0.03）具有轨道周期的二进制系统$ p _ {\ mathrm {orb}} = 15425.0 \ pm 205.7 \ \ mathrm {days} $。基于光谱信息，构建单星进化模型以适合观察到的频率。但是，拟合模型的一些重要参数与观察值不一致。与观察和理论计算中的信息融合在一起，我们得出结论，Dy Peg应该是二元系统中的SX腓尼基星，并从灰尘磁盘中积聚质量，这是其进化伴侣的残基（最有可能是在当今阶段的热白矮人）在渐近巨型巨型巨型分支相中产生的。需要进一步的观察来确认这种推论，这可能是SX腓尼基星的普遍形成机制和进化史。
In this work, the photometric data from the American Association of Variable Star Observers are collected and analyzed on the SX Phoenicis star DY Pegasi (DY Peg). From the frequency analysis, we get three independent frequencies: $f_0 = 13.71249\ \rm{c\ days^{-1}}$, $f_1 = 17.7000\ \rm{c\ days^{-1}}$, and $f_2 =18.138\ \rm{c\ days^{-1}}$, in which $f_0$ and $f_1$ are the radial fundamental and first overtone mode, respectively, while $f_2$ is detected for the first time and should belong to a nonradial mode. The $O-C$ diagram of the times of maximum light shows that DY Peg has a period change rate $(1/P_0)(\mathrm{d} P_0/\mathrm{d} t) = -(5.87 \pm 0.03) \times 10^{-8} \ \mathrm{yr^{-1}}$ for its fundamental pulsation mode, and should belong to a binary system that has an orbital period $P_{\mathrm{orb}} = 15425.0 \pm 205.7 \ \mathrm{days}$. Based on the spectroscopic information, single star evolutionary models are constructed to fit the observed frequencies. However, some important parameters of the fitted models are not consistent with that from observations. Combing with the information from observation and theoretical calculation, we conclude that DY Peg should be an SX Phoenicis star in a binary system and accreting mass from a dust disk, which was the residue of its evolved companion (most probably a hot white dwarf at the present stage) produced in the asymptotic giant branch phase. Further observations are needed to confirm this inference, and it might be potentially a universal formation mechanism and evolutionary history for SX Phoenicis stars.
