MACHO Alert 95-30：引力微透镜中扩展源效应的首次实时观测
摘要
我们呈现了对MACHO Alert 95-30的分析，这是一个朝向银河系核球的显著引力微透镜事件，其峰值放大率显著偏离标准点源微透镜模型。Alert 95-30由全球微透镜警报网络（GMAN）实时观测，在整个事件期间获得了密集采样的测光和光谱数据。我们将光变曲线的“精细结构”解释为透镜穿过源星扩展表面的凌越。这标志着对几kpc远处恒星的解析。我们发现透镜角冲击参数theta_{min}/theta_{source} = 0.715 +/- 0.003。此信息连同源的半径和距离，为透镜系统提供了额外约束。光谱和测光数据表明源是一颗M4 III星，半径为61 +/- 12 Rsun，位于核球远侧9 kpc处。我们推导出透镜相对于源的角速度为21.5 +/- 4.9 km/s/kpc，其中误差主要由源半径的不确定性主导。似然分析得出透镜质量中位数为0.67{+2.53}{-0.46} Msun，位于银河系核球，距离为6.93{+1.56}{-2.25} kpc，概率为80%。如果透镜是主序星，我们可以加入对透镜光度的约束。这将我们的估计修正为M_lens = 0.53{+0.52}{-0.35} Msun和D_lens = 6.57{+0.99}{-2.25} kpc。事件期间获取的光谱显示，H alpha和6700 A附近TiO带的吸收线等值宽度发生变化，正如扩展源微透镜所预测的那样。这很可能是由于恒星谱线的中心到临边变化所致。这些数据证明了利用微透镜临边穿越作为直接探测恒星大气工具的可能性。
引用
@article{arxiv.astro-ph/9702199,
title = {MACHO Alert 95-30 : First Real-Time Observation of Extended Source Effects in Gravitational Microlensing},
author = {C. Alcock and W. H. Allen and R. A. Allsman and D. Alves and T. S. Axelrod and T. S. Banks and S. F. Beaulieu and A. C. Becker and R. H. Becker and D. P. Bennett and I. A. Bond and B. S. Carter and K. H. Cook and R. J. Dodd and K. C. Freeman and M. Gregg and K. Griest and J. B. Hearnshaw and A. Heller and M. Honda and J. Jugaku and S. Kabe and S. Kaspi and P. M. Kilmartin and A. Kitamura and O. Kovo and M. J. Lehner and T. E. Love and D. Maoz and S. L. Marshall and Y. Matsubara and D. Minniti and M. Miyamoto and Y. Muraki and T. Nakamura and B. A. Peterson and M. R. Pratt and P. J. Quinn and I. N. Reid and M. Reid and D. Reiss and A. Retter and A. W. Rodgers and W. L. W. Sargent and H. Sato and M. Sekiguchi and P. B. Stetson and C. W. Stubbs and D. J. Sullivan and W. Sutherland and A. Tomaney and T. Vandehei and Y. Watase and D. L. Welch and T. Yanagisawa and M. Yoshizawa and P. C. M. Yock},
journal= {arXiv preprint arXiv:astro-ph/9702199},
year = {2009}
}
备注
32 pages including 6 tables, and 15 figures; Uses AASTeX 4.0; submitted to The Astrophysical Journal