A Low-Mass Planet with a Possible Sub-Stellar-Mass Host in Microlensing Event MOA-2007-BLG-192
D. P. Bennett, I. A. Bond, A. Udalski, T. Sumi, F. Abe, A. Fukui, K. Furusawa, J. B. Hearnshaw, S. Holderness, Y. Itow, K. Kamiya, A. V. Korpela, P. M. Kilmarti… 展开作者
D. P. Bennett, I. A. Bond, A. Udalski, T. Sumi, F. Abe, A. Fukui, K. Furusawa, J. B. Hearnshaw, S. Holderness, Y. Itow, K. Kamiya, A. V. Korpela, P. M. Kilmartin, W. Lin, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, T. Okumura, K. Ohnishi, Y. C. Perrott, N. J. Rattenbury, T. Sako, To. Saito, S. Sato, L. Skuljan, D. J. Sullivan, W. L. Sweatman, P. J. Tristram, P. C. M. Yock, M. Kubiak, M. K. Szymanski, G. Pietrzynski, I. Soszynski, O. Szewczyk, L. Wyrzykowski, K. Ulaczyk, V. Batista, J. P. Beaulieu, S. Brillant, A. Cassan, P. Fouque, P. Kervella, D. Kubas, J. B. Marquette
备注：
Accepted for publication in the Astrophysical Journal. Scheduled for the Sept. 1, 2008 issue
We report the detection of an extrasolar planet of mass ratio q ~ 2 x 10^(-4) in microlensing event MOA-2007-BLG-192. The best fit microlensing model shows both the microlensing parallax and finite source effects, and these can be combined to obtain the lens masses of M = 0.060 (+0.028 -0.021) M_sun for the primary and m = 3.3 (+4.9 -1.6) M_earth for the planet. However, the observational coverage of the planetary deviation is sparse and incomplete, and the radius of the source was estimated without the benefit of a source star color measurement. As a result, the 2-sigma limits on the mass ratio and finite source measurements are weak. Nevertheless, the microlensing parallax signal clearly favors a sub-stellar mass planetary host, and the measurement of finite source effects in the light curve supports this conclusion. Adaptive optics images taken with the Very Large Telescope (VLT) NACO instrument are consistent with a lens star that is either a brown dwarf or a star at the bottom of the main sequence. Follow-up VLT and/or Hubble Space Telescope (HST) observations will either confirm that the primary is a brown dwarf or detect the low-mass lens star and enable a precise determination of its mass. In either case, the lens star, MOA-2007-BLG-192L, is the lowest mass primary known to have a companion with a planetary mass ratio, and the planet, MOA-2007-BLG-192Lb, is probably the lowest mass exoplanet found to date, aside from the lowest mass pulsar planet.
The Microlensing Event MACHO-99-BLG-22/OGLE-1999-BUL-32: An Intermediate Mass Black Hole, or a Lens in the Bulge
我们对迄今为止发现的最长时间尺度的引力微透镜事件进行了重新分析：AMO-99-BLG-22/OGLE-1999-BUL-32，这是由AMO和OGLE微透镜警报系统发现的。我们对微透镜视差事件的分析包括基于银河系速度分布的标准模型的透镜位置的可能性分析，这意味着透镜可能是银河系圆盘中距离几百秒差距的~100 M太阳的黑洞或银河系凸起中的大质量恒星残骸（黑洞或中子星）。除了Mao et al（2002）在先前分析中使用的OGLE数据外，我们的新分析还包括来自CNOO、GMAN和MPS合作的数据。区分我们的分析与毛等人的分析的关键特征是对透镜运动方向的精确约束以及对该方向的含义的分析。
