Observations of Comet C/2010 X1 (Elenin) in August 2011 showed a pattern of evolution of coma morphology into an expanding, amorphous cloud of rapidly decreasing surface brightness shortly before perihelion passage, similar to C/1999 S4 (LINEAR) in 2000. However, the comet’s difficult viewing geometry at the time of disruption made it impossible to study the event using high-resolution imaging techniques and, in particular, to measure the ratio of dust to cometessimals which gives information on the internal structure of the nucleus before disruption. We report Herschel/PACS observations of the defunct Comet C/2010 X1 (Elenin), aimed at detecting its infrared ghost: the debris cloud and any remaining inert, or low-activity cometessimals that may have been released in the break-up of the nucleus, taking advantage of the comet’s close pass to Earth in mid-October 2011. These observations would have allowed us to detect, potentially, both individual surviving inert fragments of the nucleus of ≈260 m diameter (and significantly smaller, active cometessimals) and the expanding dust cloud, being particularly sensitive to coarse dust and boulders in the millimetre to metre size range. No discrete bodies were detected by Herschel to this limiting size.

中文翻译：

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与 Herschel 一起寻找 C/2010 X1 (Elenin) 的远红外幽灵

2011 年 8 月对彗星 C/2010 X1 (Elenin) 的观测表明，彗发形态演变为在近日点通过前不久表面亮度迅速降低的膨胀、无定形云，类似于 2000 年的 C/1999 S4 (LINEAR)。然而，彗星在被破坏时难以观察的几何形状使得无法使用高分辨率成像技术研究该事件，特别是无法测量尘埃与彗星的比率，从而提供有关破坏前原子核内部结构的信息。我们报告了赫歇尔/PACS 对已故彗星 C/2010 X1 (Elenin) 的观测，旨在探测其红外幽灵：碎片云和任何剩余的惰性或低活动彗星，这些彗星可能已在核，利用彗星在 2011 年 10 月中旬近距离掠过地球的机会。这些观测将使我们能够潜在地探测到直径约 260 米的原子核（以及显着更小、活跃的彗星子）的单个幸存惰性碎片和不断膨胀的彗星。尘云，对毫米到米大小范围内的粗尘和巨石特别敏感。Herschel 没有检测到这种限制尺寸的离散物体。