New insights on the binary asteroid 121 Hermione-猫眼课题宝

DOI：

10.1016/j.icarus.2009.04.032

发表时间：

2009-04

期刊：

Icarus

影响因子：

3.2

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

P. Descamps;F. Marchis;J. Ďurech;J. Emery;A. Harris;M. Kaasalainen;J. Berthier;J. Teng-Chuen-Yu;A. Peyrot;L. Hutton;J. Greene;J. Pollock;M. Assafin;R. Vieira-Martins;J. Camargo;F. Braga-Ribas;F. Vachier;D. Reichart;K. Ivarsen;J. Crain;M. Nysewander;A. Lacluyze;J. Haislip;R. Behrend;F. Colas;J. Lecacheux;L. Bernasconi;R. Roy;P. Baudouin;L. Brunetto;S. Sposetti;F. Manzini

我们报告了对主带双星c型小行星121赫敏在2007年冲日期间进行的为期6个月的光度研究的结果。我们利用了一个难得的观测机会，那就是2007年6月发生在荷米恩对点附近的年度春分。春分为地球上的观察者提供了一个侧面，这非常适合对赫敏的身体特征进行彻底的研究。本文介绍了用小型望远镜进行的观测目录，以及2005年至2008年间用Yepun 8米VLT望远镜和10米Keck望远镜获得的新的自适应光学（AO）成像。最引人注目的结果是证实了赫敏是一个分叉和细长的身体，正如Marchis等人所提出的[Marchis， F., Hestroffer， D., Descamps， P., Berthier， J., Laver， C., de Pater， I., 2005]。伊卡洛斯178,450-464]。结合AO、光度和热观测，计算出新的有效直径为187±6km。新直径比迄今公认的基于IRAS数据的辐射直径小10%左右。造成这种差异的原因是，IRAS几乎是站在极端立场上看待这个体系的。斯皮策太空望远镜的新热观测结果与AO和光曲线观测得出的直径一致。在对直径32 km的小型卫星进行新的AO天文观测的基础上，我们对轨道解进行了改进，并推导出赫敏星的容重新值为1.4+0.5/−0.2gcm−3。我们推断宏观孔隙度为~ 33+5/−20%。

We report on the results of a 6-month photometric study of the main-belt binary C-type Asteroid 121 Hermione, performed during its 2007 opposition. We took advantage of the rare observational opportunity afforded by one of the annual equinoxes of Hermione occurring close to its opposition in June 2007. The equinox provides an edge-on aspect for an Earth-based observer, which is well suited to a thorough study of Hermione’s physical characteristics. The catalog of observations carried out with small telescopes is presented in this work, together with new adaptive optics (AO) imaging obtained between 2005 and 2008 with the Yepun 8-m VLT telescope and the 10-m Keck telescope. The most striking result is confirmation that Hermione is a bifurcated and elongated body, as suggested by Marchis, et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005. Icarus 178, 450–464]. A new effective diameter of 187±6km was calculated from the combination of AO, photometric and thermal observations. The new diameter is some 10% smaller than the hitherto accepted radiometric diameter based on IRAS data. The reason for the discrepancy is that IRAS viewed the system almost pole-on. New thermal observations with the Spitzer Space Telescope agree with the diameter derived from AO and lightcurve observations. On the basis of the new AO astrometric observations of the small 32-km diameter satellite we have refined the orbit solution and derived a new value of the bulk density of Hermione of 1.4+0.5/−0.2gcm−3. We infer a macroscopic porosity of ∼33+5/−20%.

New insights on the binary asteroid 121 Hermione

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