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首页> 外文期刊>The Astrophysical journal >Far-Ultraviolet Spectroscopy of the Dwarf Novae SS Cygni and WX Hydri in Quiescence
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Far-Ultraviolet Spectroscopy of the Dwarf Novae SS Cygni and WX Hydri in Quiescence

机译:矮新星SS Cygni和WX Hydri的远紫外光谱处于静止状态

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We present time-resolved FUV spectra of the dwarf novae SS Cyg and WX Hyi in quiescence from observations using the Hopkins Ultraviolet Telescope on the Astro-1 and Astro-2 space shuttle missions and the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Both dwarf novae are characterized by blue continua that extend to the Lyman limit punctuated by broad emission lines including transitions of O VI, N V, Si IV, and C IV. The continuum of WX Hyi can be fitted with a white dwarf model with physically reasonable model parameters, but neither system actually shows unambiguous signatures of white dwarf emission. The shape and flux of the spectrum of SS Cyg cannot be self-consistently reconciled with a white dwarf providing all of the FUV continuum flux. Combination white dwarf/disk or white dwarf/optically thin plasma models improve the fit but still do not give physically reasonable model parameters for a quiescent dwarf nova. Assuming that the UV emission lines arise from the disk, the line shapes indicate that surface fluxes fall roughly as R-2 in both systems. Fits to the double-peaked line profiles in SS Cyg indicate that the FUV line-forming region is concentrated closer to the white dwarf than that of the optical lines and provide no evidence of a hole in the inner disk. Although the flux from SS Cyg was relatively constant during all of our observations, WX Hyi showed significant variability during the GHRS observations. In WX Hyi, the line and continuum fluxes are (with the exception of He II) highly correlated, indicating a link between the formation mechanisms of the line and continuum regions.
机译:我们通过使用Astro-1和Astro-2航天飞机任务的霍普金斯紫外线望远镜和哈勃太空望远镜上的Goddard高分辨率光谱仪,从观测中获得了矮新星SS Cyg和WX Hyi处于静止状态的时间分辨FUV光谱。两个矮新星的特征都是蓝色连续体,延伸到莱曼极限,并由宽发射线(包括O VI,N V,Si IV和C IV的跃迁)打断。 WX Hyi的连续体可以使用具有物理上合理的模型参数的白矮星模型进行拟合,但是两个系统都没有真正显示白矮星发射的明确特征。 SS Cyg光谱的形状和通量不能与提供所有FUV连续通量的白矮星自洽一致。白矮星/盘状或白矮星/光学稀薄等离子模型的组合可提高拟合度,但仍无法为静态矮星新星提供物理上合理的模型参数。假设紫外线发射线是从圆盘上产生的,则线的形状表示在两个系统中表面通量都大致随着R-2下降。对SS Cyg中双峰线轮廓的拟合表明,FUV线形成区域比光学线集中在白矮星附近,并且没有提供内盘孔的证据。尽管在我们所有的观测中,来自SS Cyg的通量都相对恒定,但是在GHRS观测中,WX Hyi表现出显着的可变性。在WX Hyi中,线和连续体通量高度相关(He II除外),这表明线和连续体区域的形成机制之间存在联系。

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