AI 中文总结
研究V407 Vul三星系统，通过检测天体测量摆动确认其三星性质，利用23年轨道计时约束轨道衰减，借助哈勃数据确定相关参数，预测LISA能探测到它，使其成为首个可被毫赫兹引力波天文台探测的‘验证三星’。
AI 中文摘要
AM CVn类包括质量转移的超紧凑双白矮星双星，其轨道周期在几分钟的时间尺度上。一个长期存在的谜题是，在毫赫兹引力波频段易于探测的大约五十个超紧凑“验证双星”中，没有一个处于三星配置。有很多证据暗示V407 Vul是一个轨道周期为569秒的正在合并的双白矮星AM CVn。然而，由于一颗主序星主导其可见光谱，决定性的确认具有挑战性。我们通过检测该双星569秒轨道周期上光心的显著天体测量摆动，明确确认了该源的三星性质。AM CVn和主序星成分通过引力束缚在一起，空间间距约为0.03 - 0.04''，相当于轨道间距约120AU。总共23年的轨道计时将AM CVn的轨道衰减精确到1%水平，这对于理解这类双星是否能在周期最小值时存活或合并至关重要。新的哈勃太空望远镜紫外线成像和光谱数据使得能够在更短波长下单独探测到AM CVn，揭示了一个约58000K的吸积白矮星，同时确定了3510 +140 --110 pc的可靠距离限制。在此距离下，我们预测激光干涉空间天线（LISA）将在4年的任务时间内以28.4±9.2的信噪比探测到V407 Vul，使其成为第一个具有外部第三星或‘验证三星’的可被毫赫兹引力波天文台探测到的验证双星。
英文摘要
The AM CVn class includes mass transferring, ultra-compact double white dwarf binaries with orbital periods on the timescale of minutes. A long-standing puzzle is that none of the roughly fifty ultra-compact, "verification binaries" which are easily detectable in the millihertz gravitational wave regime reside in a triple star configuration. Much evidence has hinted at V407 Vul being an inspiraling, double white dwarf AM CVn with an orbital period of 569s. Yet, a decisive confirmation has proved challenging since a main sequence star dominates its visible spectrum. We present a clear confirmation of the triple star nature of the source by detecting a significant astrometric wobble of the photocentre on the 569s orbital period of the binary. The AM CVn and the main sequence components are gravitationally bound with a spatial separation of roughly 0.03-0.04'', equating to an orbital separation of approximately 120AU. A total of 23 years of orbital timing constrained the orbital decay of the AM CVn as being precise to the 1% level, critical in understanding if this class of binary survives through a period minimum or coalesce. New Hubble Space Telescope ultra-violet imaging and spectroscopic data allowed the isolated detection of the AM CVn at shorter wavelengths, revealing an approximately 58000 K accretor white dwarf, while placing a firm distance constraint of 3510+140-110 pc. At this distance, we predict that the Laser Interferometer Space Antenna (LISA) will detect V407 Vul with a 28.4+-9.2 signal-to-noise ratio in a 4yr mission time, making it the first verification binary with an outer tertiary, or "verification triple", detectable for millihertz gravitational wave observatories.
Comments16 pages, 7 figures, 5 tables. Resubmitted to A&A after minor revision
