Observation of the First Gravitational Microlensing Event in a Sparse Stellar Field: The Tago Event
Observation of the First Gravitational Microlensing Event in a Sparse Stellar Field: The Tago Event
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DOI：
10.1086/522296
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发表时间：
2007-08
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影响因子：
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通讯作者：
A. Fukui;F. Abe;K. Ayani;M. Fujii;R. Iizuka;Y. Itow;K. Kabumoto;K. Kamiya;T. Kawabata
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作者：
A. Fukui;F. Abe;K. Ayani;M. Fujii;R. Iizuka;Y. Itow;K. Kabumoto;K. Kamiya;T. Kawabata
我们报告了在稀疏星场中观测到的第一个引力微透镜事件，其中涉及迄今为止最亮（V = 11.4 mag）和最近（~1 kpc）的源恒星。这一事件是由业余天文学家 A. Tago 于 2006 年 10 月 31 日发现的，是仙后座中一颗正常 A 型恒星 (GSC 3656-1328) 的短暂增亮，在约 15 天的时间内约 4.5 星等。对光谱观测和光变曲线的分析表明，这一事件是由引力微透镜引起的，而不是本质上变星引起的。在 30 年期间发现的这一单一事件与整个天空低至 V = 12 星等恒星的预期微透镜发生率大致一致。然而，以如此高的放大倍数 (~50) 发现事件的概率要小得多，约为 1/50，这意味着真实的事件发生率可能高于预期。这一发现表明了所有天空变化调查的潜力，利用小孔径和宽视场的望远镜进行频繁采样，发现这种罕见的瞬态事件，并利用观测结果探索银河盘结构和寻找系外行星。
We report the observation of the first gravitational microlensing event in a sparse stellar field, involving the brightest (V = 11.4 mag) and closest (~1 kpc) source star to date. This event was discovered by an amateur astronomer, A. Tago, on 2006 October 31 as a transient brightening, by ~4.5 mag during a ~15 day period, of a normal A-type star (GSC 3656-1328) in the Cassiopeia constellation. Analysis of both spectroscopic observations and the light curve indicates that this event was caused by gravitational microlensing rather than an intrinsically variable star. Discovery of this single event over a 30 year period is roughly consistent with the expected microlensing rate for the whole sky down to V = 12 mag stars. However, the probability for finding events with such a high magnification (~50) is much smaller, by a factor of ~1/50, which implies that the true event rate may be higher than expected. This discovery indicates the potential of all sky variability surveys, employing frequent sampling by telescopes with small apertures and wide fields of view, for finding such rare transient events, and using the observations to explore Galactic disk structure and search for exoplanets.