Microlens OGLE-2005-BLG-169 Implies That Cool Neptune-like Planets Are Common-猫眼课题宝

DOI：

10.1086/505421

发表时间：

2006-03

期刊：

The Astrophysical Journal Letters

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

A. Gould;A. Udalski;D. An;D. Bennett;A. Zhou;S. Dong;N. Rattenbury;B. Gaudi;P. Yock;I. Bond;G. Christie;K. Horne;Joseph M. Anderson;K. Stanek;D. Depoy;C. Han;J. Mccormick;B.-G. Park;R. Pogge;S. Poindexter;I. Soszyński;M. Szymański;M. Kubiak;G. Pietrzyński;O. Szewczyk;Ł. Wyrzykowski;K. Ulaczyk;B. Paczyński;D. Bramich;C. Snodgrass;I. Steele;M. Burgdorf;M. Bode;C. Botzler;S. Mao;S. Swaving

我们在超高倍（a ~ 800）微透镜事件OGLE-2005-BLG-169中探测到一个海王星质量比（q≃8 × 10-5）的行星伴星。如果其母恒星是一颗主序星，它的质量为M ~ 0.5 M☉，这意味着它的行星质量为~13 M⊕，预计距离为~2.7 AU。当对其峰值进行严密监测时，类似OGLE-2005-BLG-169的高倍率事件对海王星质量比行星几乎完全敏感，预计距离为0.6-1.6爱因斯坦半径，相当于目前的1.6-4.3天文单位。只有另外两个这样的事件被监测得足够好，可以探测到海王星，所以这个探测本身就表明海王星质量比行星是常见的。此外，最近在一次低倍率事件中，在与其母恒星相似的距离上发现了另一颗海王星，这种情况更常见，但单独对行星的敏感度要低得多。将这两个探测结果结合起来，在仅仅0.4年的行星-恒星分离过程中，就能得到90%的上下限f = 0.38。特别是，在90%的置信度下，b>为16%。这颗母恒星没有木星质量的伴星，它们与被探测到的行星的投影距离在5倍之内。透镜-光源相对固有运动为μ ~ 7 ~ 10 mas -1，这意味着如果透镜足够亮，I > 23.8，它将在峰值后3年被哈勃空间望远镜探测到。这样就可以更精确地估计透镜的质量和距离，从而估计行星的质量和预计的距离。OGLE-2005-BLG-169Lb类似的行星绕着附近的恒星运行，很难通过其他行星探测方法探测到，包括径向速度、凌日和天体测量。

We detect a Neptune mass ratio (q ≃ 8 × 10-5) planetary companion to the lens star in the extremely high magnification (A ~ 800) microlensing event OGLE-2005-BLG-169. If the parent is a main-sequence star, it has mass M ~ 0.5 M☉, implying a planet mass of ~13 M⊕ and projected separation of ~2.7 AU. When intensely monitored over their peak, high-magnification events similar to OGLE-2005-BLG-169 have nearly complete sensitivity to Neptune mass ratio planets with projected separations of 0.6-1.6 Einstein radii, corresponding to 1.6-4.3 AU in the present case. Only two other such events were monitored well enough to detect Neptunes, and so this detection by itself suggests that Neptune mass ratio planets are common. Moreover, another Neptune was recently discovered at a similar distance from its parent star in a low-magnification event, which are more common but are individually much less sensitive to planets. Combining the two detections yields 90% upper and lower frequency limits f = 0.38 over just 0.4 decades of planet-star separation. In particular, f > 16% at 90% confidence. The parent star hosts no Jupiter-mass companions with projected separations within a factor 5 of that of the detected planet. The lens-source relative proper motion is μ ~ 7-10 mas yr-1, implying that if the lens is sufficiently bright, I ≲ 23.8, it will be detectable by the Hubble Space Telescope by 3 years after peak. This would permit a more precise estimate of the lens mass and distance and, so, the mass and projected separation of the planet. Analogs of OGLE-2005-BLG-169Lb orbiting nearby stars would be difficult to detect by other methods of planet detection, including radial velocities, transits, and astrometry.

Microlens OGLE-2005-BLG-169 Implies That Cool Neptune-like Planets Are Common

文献摘要

被引文献

相似文献