标题： EUVE J0425.6-5714：一个新发现的AM Herculis星 显示英文标题

标题： EUVE J0425.6-5714: A Newly Discovered AM Herculis Star

摘要： 我们在使用EUVE卫星进行25天观测时意外发现了一个新的AM Her星。 在该源的EUVE深空调查成像器光变曲线中存在一个85.82分钟的相干周期。 通过一个19等的蓝星进行了光谱识别，该星具有H和He发射线以及典型的磁性灾变变星的宽广回旋谐波。 从回旋谐波的间距估计了极区磁场的下限为46 MG。 EUVE J0425.6-5714也在覆盖两个月的档案ROSAT HRI观测中被检测到，其稳定且高度结构化的光变曲线使我们能够拟合一个相干的历表，将ROSAT和EUVE数据在1.3年的间隔内联系起来。 推导出的周期为85.82107 +/- 0.00020分钟，历表在2005年之前应准确到0.1个周期。 狭窄但不完全的X射线掩食表明，这个物体属于AM Her星群体，其观测几何形状使得吸积流周期性地遮挡白矮星表面的软X射线发射吸积斑点。 ASCA同时观测中未检测到硬X射线，这表明软X射线至少要强一个数量级，这与已知的大磁场AM Her星的趋势一致。 这个物体不应与塞弗特星系1H 0419-577 (= LB 1727)混淆，后者是另一个距离仅4'的X射线/EUV源，是这些监测观测的主要目标。 显示英文摘要

摘要： We detected a new AM Her star serendipitously in a 25 day observation with the EUVE satellite. A coherent period of 85.82 min is present in the EUVE Deep Survey imager light curve of this source. A spectroscopic identification is made with a 19th magnitude blue star that has H and He emission lines, and broad cyclotron humps typical of a magnetic cataclysmic variable. A lower limit to the polar magnetic field of 46 MG is estimated from the spacing of the cyclotron harmonics. EUVE J0425.6-5714 is also detected in archival ROSAT HRI observations spanning two months, and its stable and highly structured light curve permits us to fit a coherent ephemeris linking the ROSAT and EUVE data over a 1.3 yr gap. The derived period is 85.82107 +/- 0.00020 min, and the ephemeris should be accurate to 0.1 cycles until the year 2005. A narrow but partial X-ray eclipse suggests that this object belongs to the group of Am Her stars whose viewing geometry is such that the accretion stream periodically occults the soft X-ray emitting accretion spot on the surface of the white dwarf. A non-detection of hard X-rays from ASCA observations that are contemporaneous with the ROSAT HRI shows that the soft X-rays must dominate by at least an order of magnitude, which is consistent with a known trend among AM Her stars with large magnetic field. This object should not be confused with the Seyfert galaxy 1H 0419-577 (= LB 1727), another X-ray/EUV source which lies only 4' away, and was the principal target of these monitoring observations.