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>Pulsations and Line Profile Changes in the Ultraviolet Spectrum of Hercules X-1: Results from a Multiwavelength Campaign
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Pulsations and Line Profile Changes in the Ultraviolet Spectrum of Hercules X-1: Results from a Multiwavelength Campaign
We report simultaneous X-ray and ultraviolet observations of the X-ray binary pulsar Hercules X-1, obtained over nearly half of a 1.7 day binary orbit using the ASCA X-ray telescope and the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The GHRS resolved, for the first time, two moving emission components. One feature in the N V λλ1238.8, 1242.8 doublet is broad (FWHM ≈ 1000 km s–1) and the other is narrow (FWHM ≈ 150 km s–1). We attribute the broad emission line to the X-ray—illuminated surface of a Keplerian accretion disk and the narrow line to the X-ray-heated atmosphere of the companion star, HZ Her. Near orbital phase orb = 0.80 (simultaneous with a pre-eclipse X-ray dip), the N V λ1242.8 component became stronger than the N V λ1238.8 component. Later in the orbit, the blue edge of the broad lines diminished as the approaching side of the accretion disk was occulted by HZ Her. UV continuum pulsations were detected for the first time, with an amplitude ≈ 0.5% of the steady flux. The pulse shapes of the UV continuum and hard X-rays were similar at orb = 0.83 but not at orb = 0.56. We found evidence for a stronger pulsation (amplitude ≈ 15%) within a narrow (0.25 ?) segment of the broad 1242.8 ? N v component, only at W erb = 0.80. We briefly discuss some implications of these observations for the gas flows in the Her X-1 system.
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机译：我们报告了使用哈勃望远镜上的ASCA X射线望远镜和戈达德高分辨率光谱仪（GHRS）在1.7天双星轨道近一半的位置上获得的X射线双星脉冲星大力神X-1的同时X射线和紫外观测结果太空望远镜。 GHRS首次解决了两个移动的排放成分。 N V λλ1238.8、1242.8 doublet中的一个特征较宽（FWHM≈1000 km s-1），另一个较窄（FWHM≈150 km s-1）。我们将宽发射线归因于开普勒吸积盘的X射线照射表面，而窄线归因于伴星HZ Her的X射线加热的气氛。在轨道相位球体= 0.80附近（与蚀前X射线倾角同时），N Vλ1242.8分量变得比N Vλ1238.8分量更强。在轨道的后面，由于HZ Her掩盖了吸积盘的一侧，因此宽线的蓝色边缘变小了。首次检测到紫外线连续脉动，幅度约为稳定通量的0.5％。 UV连续谱和硬X射线的脉冲形状在orb = 0.83时相似，但在orb = 0.56时不相似。我们发现有证据表明在较大的1242.8？的狭窄段（0.25？）内有更强的脉动（振幅≈15％）。 N v分量，仅在W erb = 0.80时。我们简要讨论了这些观测结果对Her X-1系统中气流的一些影响。
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