发表机构
University of Notre Dame; University of California, Berkeley; Lawrence Berkeley National Laboratory; Bay Area Environmental Research Institute; University College Cork; The University of Manchester; University of Washington; University of Virginia; Observatorio Astronómico “Las Pegueras”; Warren Williams College; AAVSO（圣母大学; 加州大学伯克利分校; 劳伦斯伯克利国家实验室; 湾区环境研究所; 科克大学学院; 曼彻斯特大学; 华盛顿大学; 弗吉尼亚大学; 拉斯佩格拉斯天文台; 沃伦威廉姆斯学院; 美国变星观测者协会）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过时域光谱发现矮新星V844 Her具有29.3分钟周期的磁吸积特征，将其认定为中介偏振星，并利用多波段观测揭示其超级爆发期间X射线计数率下降源于爆发盘额外柱密度导致的软X射线损失。
AI 中文摘要
我们展示了SU UMa型矮新星V844 Her在静止期的时域光谱。我们发现了以29.3±0.1分钟周期调制的高速巴耳末线和He I发射特征。该光谱周期性与仅在超级爆发期间探测到的光度周期相同。将此解释为白矮星上磁吸积的结果，我们将V844 Her认定为中介偏振星（IP）。白矮星的自转周期最可能为29.3分钟。在少数IP系统中，光学调制以自转频率的两倍出现，因此我们不能排除自转周期为58.6分钟的可能性。V844 Her的轨道周期仅为1.31小时，这意味着该系统在已确认的IP中拥有最短的双星周期，并且轨道与自转周期之比最小之一。我们展示了2023年超级爆发期间V844 Her的大量光学、紫外和X射线观测。与静止期相比，超级爆发期间XRT计数率下降。虽然超级爆发期间增强的质传输可能增加X射线产生，但我们提出计数率的下降是由于爆发盘带来的额外柱密度导致软X射线损失所致。
英文摘要
We present time-series spectroscopy of the SU UMa-type dwarf nova V844 Her during quiescence. We discover high-velocity Balmer and He I emission features modulated at a period of 29.3$\pm$0.1 minutes. The spectroscopic periodicity is identical to the photometric period detected only during superoutbursts. Interpreting this as the result of magnetic accretion onto the white dwarf, we identify V844 Her as an intermediate polar (IP). The spin period of the white dwarf is most likely to be 29.3 minutes. In a few IP systems, optical modulation is seen at twice the spin frequency, so we can not rule out that the spin period is 58.6 minutes. The orbital period of V844 Her is only 1.31 hr, meaning that the system has the shortest binary period and one of the smallest orbit-to-spin ratios of the confirmed IPs. We present extensive optical, ultraviolet, and X-ray observations of V844 Her during the 2023 superoutburst. Compared with quiescence, the XRT count rate decreases during superoutburst. While the enhanced mass transfer during the superoutburst likely increases X-ray production, we propose that the drop in the count rate comes from the loss of soft X-rays due to an additional column from the outbursting disk.
Comments16 pages, 15 figures
