Sion Edward M, Godon Patrick, Mikolajewska Joanna, Sabra Bassem, Kolobow Craig
Department of Astrophysics & Planetary Science, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, USA.
Copernicus Astronomical Center, Warsaw, Poland.
Astron J. 2017 Apr;153(No 4). doi: 10.3847/1538-3881/aa62a9. Epub 2017 Mar 17.
We have conducted a spectroscopic analysis of the far ultraviolet archival spectra of four symbiotic variables, EG And, AE Ara, CQ Dra and RW Hya. RW Hya and EG And have never had a recorded outburst while CQ Dra and AE Ara have outburst histories. We analyze these systems while they are in quiescence in order to help reveal the physical properties of their hot components via comparisons of the observations with optically thick accretion disk models and NLTE model white dwarf photospheres. We have extended the wavelength coverage down to the Lyman Limit with FUSE spectra. We find that the hot component in RW Hya is a low mass white dwarf with a surface temperature of 160,000K. We re-examine whether or not the symbiotic system CQ Dra is a triple system with a red giant transferring matter to a hot component made up of a cataclysmic variable in which the white dwarf has a surface temperature as low as ∼20,000K. The very small size of the hot component contributing to the shortest wavelengths of the FUSE spectrum of CQ Dra agrees with an optically thick and geometrically thin (∼4% of the WD surface) hot (∼ 120, 000K) boundary layer. Our analysis of EG And reveals that its hot component is a hot, bare, low mass white dwarf with a surface temperature of 80-95,000K, with a surface gravity log() = 7.5. For AE Ara, we also find that a low gravity (log() ∼ 6) hot ( ∼ 130, 000K) WD accounts for the hot component.
我们对四个共生变星EG And、AE Ara、CQ Dra和RW Hya的远紫外存档光谱进行了光谱分析。RW Hya和EG And从未有过爆发记录，而CQ Dra和AE Ara有爆发历史。我们在这些系统处于宁静状态时对其进行分析，以便通过将观测结果与光学厚吸积盘模型和非局部热动平衡（NLTE）模型白矮星光球进行比较，来揭示其热成分的物理性质。我们利用远紫外光谱探测器（FUSE）光谱将波长覆盖范围扩展到莱曼限。我们发现RW Hya中的热成分是一颗表面温度为160,000K的低质量白矮星。我们重新审视共生系统CQ Dra是否是一个三合星系统，其中一颗红巨星将物质转移到一个由激变变星组成的热成分上，该激变变星中的白矮星表面温度低至约20,000K。对CQ Dra的FUSE光谱最短波长有贡献的热成分非常小，这与一个光学厚且几何薄（约为白矮星表面的4%）、温度高（约120,000K）的边界层相符。我们对EG And的分析表明，其热成分是一颗表面温度为80 - 95,000K、表面重力log(g)=7.5的热的、裸露的低质量白矮星。对于AE Ara，我们还发现一个低重力（log(g) ∼ 6）、温度高（ ∼ 130,000K）的白矮星构成了热成分。
