Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System
Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System
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DOI：
10.3847/1538-4357/ac3a72
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发表时间：
2021-09
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通讯作者：
T. Otani;A. Lynas-Gray;D. Kilkenny;C. Koen;T. von Hippel;M. Uzundag;M. Vučković;C. Pennock;R. Silvotti
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作者：
T. Otani;A. Lynas-Gray;D. Kilkenny;C. Koen;T. von Hippel;M. Uzundag;M. Vučković;C. Pennock;R. Silvotti
AQ Col（EC 05217-3914）是最早被发现的脉动次矮星B（sdB）之一，一直被认为是一颗单颗星星。AQ Col的光度监测显示了一个周期为486天的脉动时间变化，解释为一个宽双星的反射运动造成的时间延迟，该双星与一个预计质量大于1.05 M的看不见的伴星形成。光谱和色星等图表明伴星不是主序星星星，而是白色或中子星星星。脉动时间的变化也表明，该系统的偏心率为0.424，这是远远大于任何已知的sdB长周期双星系统。这可能是由于sdB星星的另一个短周期伴星的存在。在1996年12月5日获得的两个光谱显示，在46.1分钟内径向速度变化为49.1 km s−1，这表明宽双星中的热亚矮星本身是一个紧密的双星，与另一个看不见的白色矮星或中子星星伴星形成;如果进一步的观测表明这种解释是正确的，AQ Col是一个值得进一步研究的有趣的三重系统。
AQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. Photometric monitoring of AQ Col reveals a pulsation timing variation with a period of 486 days, interpreted as time delay due to reflex motion in a wide binary formed with an unseen companion with expected mass larger than 1.05 M ⊙. The optical spectra and color–magnitude diagram of the system suggested that the companion is not a main-sequence star but a white dwarf or neutron star. The pulsation timing variation also shows that the system has an eccentricity of 0.424, which is much larger than any known sdB long period binary system. That might be due to the existence of another short period companion to the sdB star. Two optical spectra obtained on 1996 December 5 show a radial velocity change of 49.1 km s−1 in 46.1 minutes, which suggests the hot subdwarf in the wide binary is itself a close binary formed with another unseen white dwarf or neutron star companion; if further observations show this interpretation to be correct, AQ Col is an interesting triple system worthy of further study.