Hubble Space Telescope observations of the nucleus and inner coma of comet 67P/Churyumov-Gerasimenko
Hubble Space Telescope observations of the nucleus and inner coma of comet 67P/Churyumov-Gerasimenko
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哈勃太空望远镜对 67P/Churyumov-Gerasimenko 彗星的核心和内部彗发的观测
DOI：
10.1051/0004-6361:20065253
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发表时间：
2006
影响因子：
6.5
通讯作者：
P. Gutiérrez
中科院分区：
文献类型：
--
作者：
P. Lamy;I. Tóth;H. Weaver;L. Jorda;M. Kaasalainen;P. Gutiérrez
语境。继原定于 2003 年 1 月发射罗塞塔号宇宙飞船的推迟之后，67P/Churyumov-Gerasimenko 彗星成为最合适的新目标。然而，一个关键问题是其核的尺寸，即其质量，因为菲莱表面模块设计用于着陆在半径不大于约1.5公里的核上。目标。因此，及时对 67P/C-G 核心进行表征，以便在新发射之前对所需的设计采取适当的行动，对于任务的成功至关重要。方法。我们使用了哈勃太空望远镜 (HST) 的宽视场行星相机 2 (WFPC2)，其卓越的空间分辨率使我们能够准确地将核信号与彗发信号分开。观测于 2003 年 3 月 12 日至 13 日进行，当时彗星距太阳 2.50 个天文单位，距地球 1.52 个天文单位，相位角为 4.8°。结果。 67P/Churyumov-Gerasimenko 彗星的核心很容易被探测到，我们在 Johnson-Kron-Cousins 光度系统中测量了它的 V 和 R 星等。假设原子核是球形的，R 波段的几何反照率为 0.04，相位系数为 0.04 mag/deg，我们得出的半径为 1.98 ± 0.02 km。球体解的半轴 a = 2.41 km，b = c = 1.55 km，自转周期为 12.41 ± 0.41 h。我们反转了光变曲线并求解了一个完整的三维核，在我们观测时，从~80°的方位角（即近赤道视图）观察，其总体尺寸为 4.56 × 3.81 x 3.44 km。与其他约束结合使用时，极点方向为 RA = 40° +70° 20° 且 Dec = +70 ± 10°（顺行旋转）或 RA = 250 ± 30° 且 Dec = -70 ± 10°（逆行旋转）。细胞核的颜色为中等红色，(V - R) = 0.52 ±0.05。通过对尘埃慧发的分析，我们得出 A fp = 40.2 ±0.3 cm，尘埃产生率 Q d ∼ 4 kg s -1 ，并表征了其颜色。
Context. Following the postponement of the launch of the Rosetta spacecraft scheduled in January 2003, comet 67P/Churyumov-Gerasimenko emerged as the most suitable new target. However a critical issue was the size, that is, the mass of its nucleus, as the surface module Philae was designed to land on a nucleus with a radius no larger than approximately 1.5 km. Aims. It was therefore crucial to the success of the mission to achieve a timely characterization of the nucleus of 67P/C-G so as to take any proper action on the design needed before the new launch. Methods. We used the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope (HST) whose superior spatial resolution enabled us to accurately separate the signal of the nucleus from that of the coma. The observations were performed on 12 and 13 March 2003, when the comet was 2.50 AU from the Sun, 1.52 AU from the Earth, and at a phase angle of 4.8°. Results. The nucleus of comet 67P/Churyumov-Gerasimenko was easily detected, and we measured its V and R magnitudes in the Johnson-Kron-Cousins photometric system. Assuming that the nucleus is spherical, with a geometric albedo of 0.04 and a phase coefficient of 0.04 mag/deg for the R band, we derived a radius of 1.98 ± 0.02 km. The spheroidal solution has semiaxes a = 2.41 km and b = c = 1.55 km and a rotational period of 12.41 ± 0.41 h. We inverted the light curve and solved it for a full three-dimensional nucleus having an overall size of 4.56 × 3.81 x 3.44 km viewed at an aspect angle of ∼80° (i.e., near equatorial view) at the time of our observations. When combined with other constraints, the direction of the pole is found at either RA = 40° +70° 20° and Dec = +70 ± 10° (prograde rotation) or RA = 250 ± 30° and Dec = -70 ± 10° (retrograde rotation). The color of the nucleus is moderately red with (V - R) = 0.52 ±0.05. From an analysis of the dust coma, we derived A fp = 40.2 ±0.3 cm, a dust production rate Q d ∼ 4 kg s -1 , and we characterized its color.