Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage
Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage
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2010 年经过近日点期间彗星 81P/Wild 2 的光度观测
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S. Marchi
中科院分区：
文献类型：
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作者：
I. Bertini;C. Barbieri;T. Ho;M. Lazzarin;G. Cremonese;M. Küppers;S. Magrin;S. Marchi
上下文。木星家族彗星81P/Wild 2是美国宇航局星尘任务的目标，在研究太阳系原始物体的背景下非常重要。首先，它最近才偏转到现在的轨道，在1974年轨道改变之前，它已经在更高的日心距离上度过了至少300年。因此，这颗彗星很可能经历了最近的一次激活，其原始物质的变化很小。其次，它是唯一一颗彗发物质被带回地球进行实验室分析的彗星。在2010年2月9日到9月9日期间，我们一共观测了这个天体11个晚上。
Context. The Jupiter-family comet 81P/Wild 2, target of the NASA Stardust mission, is very important in the context of the studies of pristine objects in the solar system. First, it was only recently deflected into the present orbit, having spent at least 300 yr at higher heliocentric distance prior to the orbital change in 1974. It is therefore likely that the comet experienced a recent activation with consequent low alteration of its original material. Second, it is the only comet whose coma material was brought back to Earth for laboratory analysis. We observed the object between 2010 February 9 and September 9 for a total of 11 nights during the 2010 perihelion passage.
Aims. The goals of the campaign were the characterization of the comet’s dust activity and the comparison with previous apparitions to derive hints on the secular behavior of the object.
Methods. Broadband R- and I-images were acquired using three instruments: ALFOSC, CAMELOT, and TCP. The first one is mounted at the Nordic Optical Telescope on La Palma, while the second and the third are mounted at the Instituto de Astrofisica de Canarias 0.82-m telescope on Tenerife. We analyzed the presence and variability of dust structures in the coma with image-enhancing techniques, the radial profile of the dust brightness, and we measured the dust production rate and the dust reddening.
Results. We found evidence of a long-lasting sunward fan and anti-solar tail activity throughout all our observations up to a heliocentric distance of 2.42 AU. Afρ measurements suggest a pre-perihelion peak of the activity, caused by a seasonal effect, plus two post-perihelion outbursts. Both spatial and Afρ radial profiles indicate a steady-state coma at nucleocentric distances greater than ~1000–2000 km. The color analysis reveals a moderately reddened dust with a 6–9%/1000 A reddening, consistent with the current picture of cometary dust. The second outburst emitted dust with lower reddening.
Conclusions. The comparison with previous perihelion passages points toward a recurrent main activity always driven by the same areas on the nucleus, producing dust with similar characteristics and in similar coma structures in different years. Our Afρ measurement at the longest heliocentric distance suggests the comet was less dust-productive in 2010, pointing toward a possible secular aging of the object and its activity. The change of dust colors during the unusual second outburst suggests that an internal part of the nucleus has different physical properties compared with those that produce the recurrent main activity, pointing toward a heterogeneous comet.
星尘之后的短周期木星家族彗星
影响因子：
2.4
作者：
Burchell M
通讯作者：
Burchell M