First Observation of Parallax in a Gravitational Microlensing Event
First Observation of Parallax in a Gravitational Microlensing Event
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首次观测引力微透镜事件中的视差
DOI：
10.1086/309783
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
W. Sutherland
中科院分区：
文献类型：
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作者：
C. Alcock;C. Alcock;R. Allsman;D. Alves;D. Alves;T. Axelrod;T. Axelrod;D. Bennett;D. Bennett;K. Cook;K. Cook;K. Freeman;K. Griest;K. Griest;J. Guern;J. Guern;M. Lehner;M. Lehner;S. Marshall;S. Marshall;B. Peterson;M. Pratt;M. Pratt;P. Quinn;A. Rodgers;C. Stubbs;C. Stubbs;C. Stubbs;W. Sutherland;W. Sutherland
我们在引力微透镜事件中首次探测到视差效应。仅从地球观测到的引力微透镜事件中的视差表现为地球围绕太阳运动产生的（否则对称的）光曲线的扭曲。如果事件持续时间不少于一年，如果透镜的投射速度不比地球绕太阳的轨道速度大多少，就可以检测到这种扭曲。这里呈现的事件的持续时间（或爱因斯坦直径穿越时间）为t³= 220天，并清楚地显示了地球运动造成的扭曲。我们发现透镜的投影速度为= 75±5 km s-1，与银河经度增加方向成28°±4°角，与预期的银河盘透镜一致。对这一事件的似然分析得出了到透镜的距离和质量的估计：Dlens = 1.7+1.1−0.7 kpc, M = 1.3+1.3−0.6 M☉。这表明透镜是白矮星或中子星之类的残余物。这个透镜有可能是一颗主序星，尽管可能性较小。如果是这样，我们可以在分析中加上透镜观测到的通量的上限。这修正了估计为Dlens = 2.8+1.1−0.6 kpc和M = 0.6+0.4−0.2 M☉。
We present the first detection of parallax effects in a gravitational microlensing event. Parallax in a gravitational microlensing event observed only from the Earth appears as a distortion of the (otherwise symmetrical) light curve arising from the motion of the Earth around the Sun. This distortion can be detected if the event duration is not much less than a year and if the projected velocity of the lens is not much larger than the orbital velocity of the Earth about the Sun. The event presented here has a duration (or Einstein diameter crossing time) of t̂ = 220 days and clearly shows the distortion resulting from the Earth's motion. We find that the projected velocity of the lens is = 75 ± 5 km s-1 at an angle of 28° ± 4° from the direction of increasing galactic longitude, as expected for a lens in the galactic disk. A likelihood analysis of this event yields estimates of the distance to and mass of the lens: Dlens = 1.7+1.1−0.7 kpc and M = 1.3+1.3−0.6 M☉. This suggests that the lens is a remnant such as a white dwarf or neutron star. It is possible, though less likely, that the lens is a main-sequence star. If so, we can add our upper limit on the observed flux from the lens to the analysis. This modifies the estimates to Dlens = 2.8+1.1−0.6 kpc and M = 0.6+0.4−0.2 M☉.