CCD Photometry of Cometary Nuclei, I: Observations from 1990–1995
CCD Photometry of Cometary Nuclei, I: Observations from 1990–1995
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彗星核的 CCD 光度测量，I：1990-1995 年的观测
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
R. G. Hutton
中科院分区：
文献类型：
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作者：
J. Licandro;G. Tancredi;M. Lindgren;H. Rickman;R. G. Hutton
1990年4月至1995年7月，对18颗木星系彗星进行了中、大日心距离的CCD测光。这是一项长期观测计划的一部分，旨在获得它们的核震级。观测是由位于欧洲南方天文台La Silla的1.54米丹麦望远镜、位于La Palma天文台del Roque de los Muchachos的2.5米北欧光学望远镜（NOT）、Pic du Midi的2.0米望远镜和阿根廷CASLEO的2.15米望远镜完成的。我们对绝对核震级的估计与以前的测定进行了比较。考虑到典型的几何反照率p v =0.04，计算了原子核有效半径R的估计（有时是上限）。最小的半径为37P/Forbes (R =1.0 km)，而最大的半径为65P/Gunn (R =11.0 km)，但在这种情况下，观测到的彗星非常活跃。只要有可能，就会将彗星的图像轮廓与恒星的轮廓进行比较，以确定是否存在微弱的昏迷。其中7颗彗星处于活跃状态，其中6颗的日心距离大于4天文单位。对这一意外活动也进行了讨论。我们发现大日心距离的活动与近日点距离最近的下降跳跃之间有很强的相关性。
Abstract CCD photometry of 18 Jupiter family comets, observed at medium and large heliocentric distances, was carried out between April 1990 and July 1995. This is part of a long-term observational program designed to obtain their nuclear magnitudes. The observations were made with the 1.54-m Danish Telescope at ESO La Silla, the 2.5-m Nordic Optical Telescope (NOT) at Observatorio del Roque de los Muchachos (La Palma), the 2.0-m telescope at Pic du Midi, and the 2.15-m telescope at CASLEO, Argentina. Our estimates of the absolute nuclear magnitudes are discussed in comparison with previous determinations. Estimates (sometimes upper limits) for the effective radius ( R ) of the nuclei are computed considering a typical geometric albedo p v =0.04. The lowest radius found is the one of 37P/Forbes ( R =1.0 km) while the largest corresponds to 65P/Gunn ( R =11.0 km), but in this case the comet was observed very active. Wherever possible, cometary image profiles are compared with stellar profiles, in order to determine the existence of a faint coma. Seven of the comets were active, six of them at heliocentric distances larger than 4 AU. This unexpected activity is also discussed. We find a strong correlation between activity at large heliocentric distances and recent downward jumps in perihelion distance.