矮新星IP Peg的近红外光谱研究
A multicolor near-infrared study of the dwarf nova IP Peg
摘要：
本文报道了食矮新星IP Peg在静止期的$JHK_{s}$光变曲线分析。光变曲线主要由质量施主恒星的椭球变化，以及来自吸积盘和亮点的各向异性发射的额外贡献。在$J$和$H$的光变曲线上可以看到二次日食，在最低光时分别有2%和3%的通量消失。我们模拟了观测到的第二颗恒星的椭球变化（包括其内表面可能的照明效应），以找到$q = 0.42$的质量比和$i = 84.5^{o} $的倾角，在不确定性的三个波段中保持一致。照明效果可以忽略不计。在$J$、$H$和$K_{s}$中，次级分别占通量的83%、84%和88%。我们拟合了一个黑体光谱的$JHK_{s}$流量的第二颗星，找到一个温度为$T_{bb} = 3100\pm500 K$和距离$d=115\pm30$ pc的系统。我们减去了第二颗恒星的贡献，并将3-D日食映射技术应用于所得到的光变曲线，以映射具有半张角$α$和在亮点半径处的圆形边缘的圆盘的表面亮度。日食图显示了沿亮点位置前方气流轨迹的增强发射，提供了气流溢出的证据。对于$R < 0.3R_{L1}$，推断出的圆盘中的径向亮度-温度分布是平坦的，温度$\simeq 3500K$和颜色与冷的不透明辐射体一致。
英文摘要：
We report the analysis of $JHK_{s}$ light curves of the eclipsing dwarf nova IP Peg in quiescence. The light curves are dominated by the ellipsoidal variation of the mass-donor star, with additional contributions from the accretion disc and anisotropic emission from the bright spot. A secondary eclipse is visible in the $J$ and $H$ light curves, with 2% and 3% of the flux disappearing at minimum light, respectively. We modeled the observed ellipsoidal variation of the secondary star (including possible illumination effects on its inner face) to find a mass ratio of $q = 0.42$ and an inclination of $i = 84.5^{o} $, consistent in the three bands within the uncertainties. Illumination effects are negligible. The secondary is responsible for 83%, 84% and 88% of the flux in $J$, $H$ and $K_{s}$, respectively. We fitted a black body spectrum to the $JHK_{s}$ fluxes of the secondary star to find a temperature of $T_{bb} = 3100\pm500 K$ and a distance of $d=115\pm30$ pc to the system. We subtracted the contribution of the secondary star and applied 3-D eclipse mapping techniques to the resulting light curves to map the surface brightness of a disc with half-opening angle $α$ and a circular rim at the radius of the bright spot. The eclipse maps show enhanced emission along the stream trajectory ahead of the bright spot position, providing evidence of gas stream overflow. The inferred radial brightness-temperature distribution in the disc is flat for $R < 0.3R_{L1}$ with temperatures $\simeq 3500K$ and colors consistent with those of cool opaque radiators.
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