2021/2022年彗星67P/丘留莫夫-格拉西缅科的综合研究。II. 比色法、偏振测量、建模
A comprehensive study of comet 67P/Churyumov-Gerasimenko in the 2021/2022 apparition. II. Colorimetry, polarimetry, modeling
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中文总结 AI 辅助
该研究对2021 - 2022年彗星67P进行多技术观测，通过望远镜成像和测量，结合数值模拟，研究彗发尘埃颜色与偏振，发现其属于高偏振类别，且2015/16年后尘埃特性或有变化。
中文摘要 AI 辅助
本文介绍了我们在2021 - 2022年彗星67P出现期间进行的多技术观测研究的第二部分。第一篇论文聚焦于光度测量和光谱学，本文则研究彗发的尘埃颜色和线性偏振。利用6米口径的BTA SAO望远镜在g - sdss和r - sdss滤镜下成像，并用2.6米口径的沙因望远镜（CrAO）和2米口径的RCC望远镜进行孔径偏振测量。在47.9度（2021年10月6日）和10.5度（2022年2月6日）相位角的观测显示，在10.5度时负偏振约为0.5 - 2.5%，在47.9度时正偏振约为11%。尘埃颜色为红色，在彗核附近和彗尾约为0.8星等，在彗发和距彗核20000千米内的喷流中降至约0.2星等。空间图显示颜色指数随离彗核距离逐渐降低，偏振相应增加。数值模拟表明彗发主要由大于10微米的颗粒主导，局部偏振增强与含有较小（1 - 10微米）颗粒的区域一致。将我们的孔径测量结果与之前四次出现的数据相结合，证实彗星67P属于高偏振类别。2021/22年出现期间观测到的异常高正偏振以及相对各向同性的彗发形态，表明2015/16年出现后尘埃特性可能发生了变化。
英文摘要
This paper presents the second part of our multi-technique observational study of comet 67P during its 2021-2022 apparition. While the first paper focused on photometry and spectroscopy, here we investigate the dust color and linear polarization of the coma. Imaging in the g-sdss and r-sdss filters was obtained with the 6-m BTA SAO Telescope, and aperture polarimetry was performed with the 2.6-m Shajn Telescope (CrAO) and the 2-m RCC Telescope. Observations at phase angles of 47.9 deg (6 October 2021) and 10.5 deg (6 February 2022) show negative polarization of about 0.5-2.5% at 10.5 deg and positive polarization of about 11% at 47.9 deg. The dust color was red, reaching about 0.8 mag near the nucleus and in the tail, and decreasing to about 0.2 mag in the coma and jet within 20,000 km of the nucleus. Spatial maps reveal a gradual decrease in color index and a corresponding increase in polarization with distance from the nucleus. Numerical modeling using ballistic particle-cluster aggregates composed of equal fractions of silicates and organics indicates that the coma is dominated by particles larger than 10 micrometers, while local polarization enhancements are consistent with regions containing smaller (1-10 micrometer) grains. Combining our aperture measurements with published data from four previous apparitions confirms that comet 67P belongs to the high-polarization class. The unusually high positive polarization observed during the 2021/22 apparition, together with the relatively isotropic coma morphology, suggests that the dust properties may have changed after the 2015/16 apparition.
