Physical studies of 81P/Wild 2 from the last two apparitions
Physical studies of 81P/Wild 2 from the last two apparitions
复制标题
81P/Wild 2 最后两次显现的物理研究
DOI：
10.1051/0004-6361/201116848
复制
发表时间：
2012
影响因子：
6.5
通讯作者：
W. Ip
中科院分区：
文献类型：
--
作者：
Zhong;L. Lara;J. Vincent;W. Ip
语境。我们从 ESO 档案中下载了 81P/Wild 2 彗星 2004 年 5 月和 6 月的数据，并在 2010 年 1 月至 8 月这颗彗星自 1978 年发现以来第六次经过近日点期间对其进行了监测。光度数据用于监测彗星的气体和尘埃活动，作为日心距离的函数。非光度数据用于分析尘埃彗形形态的演变。目标。分析观测数据的目的是描述彗核接近太阳时彗星活动的演化特征。我们还旨在评估最后两次显现的气体和尘埃产生率，并研究 2010 年最后一次显现期间尘埃彗发形态的演变。方法。长缝光谱数据是使用安装在 3.6 处的 EFOSC2 仪器获取的。 m ESO望远镜位于智利，而窄带和宽带图像是使用台湾鹿林天文台的1米望远镜获得的。图像增强技术用于研究 R 宽带图像中尘埃彗差形态的演变，并且我们对这些尘埃射流的演变进行了建模。在可能的情况下，我们研究了灰尘和气体的产生速率，以及太阳反太阳方向上灰尘亮度的径向分布。结果。形态分析帮助我们使用拉森-塞卡尼亚滤波器检测尘埃彗发中的射流结构。 2004年5月，在向阳的一侧只发现了一处特征。 2010年，其中一项喷气式飞机功能在1月后被关闭，4月至5月期间至少发现了四架新喷气式飞机。物理性质显示，4420 Å 至 6840 Å 之间的平均红化为每 1000 Å 8.4%，C2 与 CN 生产率比的平均对数结果为 –0.454± 0.13，这将根据分类学分类将 Wild 2 置于“贫化”类别中。 CN 和 C2 气体产生速率的径向依赖性斜率与许多其他木星族彗星的观测结果非常一致。鹿林天文台拍摄的图像中地表亮度的斜率在0.98~1.38之间，其范围区间为2000~30000km，大致符合ρ−1定律。但外侧区域（4.0≤ log ρ(km)≤ 4.5）向太阳方向径向剖面的梯度比内侧区域（3.3≤ log ρ(km)≤ 4.0）稍陡。
Context. We downloaded data for the comet 81P/Wild 2 for May and June 2004 from the ESO archive and monitored this comet from January to August 2010 during its 6th perihelion passage since its discovery in 1978. Photometric data were used to monitor the comet’s gas and dust activity as a function of heliocentric distance. Non-photometric data were used for an analysis of the evolution of the dust coma morphology. Aims. The goal of the analysis of the observational data was to characterize the evolution of the cometary activity as the nucleus approaches the Sun. We also aimed to assess the gas and dust production rates for the last two apparitions and investigated the evolution of the dust coma morphology during the last passage in 2010. Methods. The long-slit spectra data were acquired with the EFOSC2 instrument mounted at the 3.6. m ESO telescope in Chile, while narrowband and broadband images were obtained using the 1-m telescope at the Lulin Observatory in Taiwan. Image enhancing techniques were used to investigate the evolution of the dust coma morphology in the R-broadband images, and we modeled the evolution of these dust jets. Where possible, we studied the dust and gas production rate, and the radial profiles of the dust brightness in the Sun-anti-sunward directions. Results. The morphological analysis helped us to detect the jet structures in the dust coma by using the Larson-Sekanian filter. In May 2004, only one feature had been found on the sunward side. In 2010, one of the jet features had been switched-off after January, and at least four new jets were found from April to May. The physical properties show an average reddening between 4420 Å and 6840 Å of 8.4% per 1000 Å and the average resulting log of the C2-to-CN production rate ratio is –0.454± 0.13, which would place Wild 2 in the “depleted” category according to the taxonomic classification. The slope of the radial dependence of the gas production rates for CN and C2 is very consistent with observations of many other Jupiter-family comets. The slopes of the surface brightness lie between 0.98 and 1.38 in the images taken at the Lulin observatory, whose the range interval from 2000 km to 30 000 km is roughly consistent with the ρ−1 law. However, the gradient of the radial profile in the sunward direction in the outer region (4.0≤ log ρ(km)≤ 4.5) is slightly steeper than that in the inner region (3.3≤ log ρ(km)≤ 4.0).