标题： 四颗掩食磁性激变变星的时间分辨哈勃光谱学 显示英文标题

标题： Time-Resolved HST Spectroscopy of Four Eclipsing Magnetic Cataclysmic Variables

摘要： 为磁性激变变星V1309 Ori、MN Hya、V2301 Oph和V1432 Aql提供了时间分辨的HST紫外食光谱测量数据。通过将光曲线分离到不同波段，可以区分多个发射成分。在V1309 Ori和V2301 Oph中检测到了光球热点。V1309 Ori和MN Hya的发射线光谱异常，N V 1240和N IV 1718强度表明氮元素过量。对异步V1432 Aql的三次观测覆盖了白矮星自旋与双星轨道周期约1/3的50天。光曲线随历元和波段变化。消红化的紫外光谱非常明亮，光谱能量分布结合食入射持续时间表明主要的能量源是一个温度约为35,000K的热白矮星。食期间未减弱的线发射表明食是由吸积流引起的，而非伴星。这个热白矮星与其当前的异步状态以及重新锁定的快速时间尺度相结合，表明V1432 Aql在过去75-150年内可能经历过一次新星爆发。如果磁性白矮星的旋转可以在爆发风阶段与喷出物耦合，则初级星目前加速向同步旋转并不一定与此情景相矛盾。 显示英文摘要

摘要： Time-resolved HST UV eclipse spectrophotometry is presented for the magnetic CVs V1309 Ori, MN Hya, V2301 Oph, and V1432 Aql. Separation of the light curves into wavebands allows the multiple emission components to be distinguished. Photospheric hot spots are detected in V1309 Ori and V2301 Oph. The emission- line spectra of V1309 Ori and MN Hya are unusual, with the strength of N V 1240 and N IV 1718 suggesting an overabundance of nitrogen. Three epochs of observation of the asynchronous V1432 Aql cover ~1/3 of a 50-day lap cycle between the white dwarf spin and binary orbit. The light curves vary from epoch to epoch and as a function of waveband. The dereddened UV spectrum is extremely bright and the spectral energy distribution coupled with the duration of eclipse ingress indicate that the dominant source of energy is a hot (T~35,000K) white dwarf. Undiminished line emission through eclipse indicates that the eclipse is caused by the accretion stream, not the secondary star. The hot white dwarf, combined with its current asynchronous nature and rapid timescale for relocking, suggests that V1432 Aql underwent a nova eruption in the past 75-150 yr. The reversed sense of asynchronism, with the primary star currently spinning up toward synchronism, is not necessarily at odds with this scenario, if the rotation of the magnetic white dwarf can couple to the ejecta during the wind phase of the eruption.