Nine recently discovered long-period comets were observed by the Solar Wind Anisotropies (SWAN) Lyman-alpha all-sky camera on board the Solar and Heliosphere Observatory (SOHO) satellite during the period of 2013 to 2016. These were C/2012 K1 (PanSTARRS), C/2013 US10 (Catalina), C/2013 V5 (Oukaimeden), C/2013 R1 (Lovejoy), C/2014 E2 (Jacques), C/2014 Q2 (Lovejoy), C/2015 G2 (MASTER), C/2014 Q1 (PanSTARRS) and C/2013 X1 (PanSTARRS). Of these 9 comets 6 were long-period comets and 3 were possibly dynamically new. Water production rates were calculated from each of the 885 images using our standard time-resolved model that accounts for the whole water photodissociation chain, exothermic velocities and collisional escape of H atoms. For most of these comets there were enough observations over a broad enough range of heliocentric distances to calculate power-law fits to the variation of production rate with heliocentric distances for pre- and post-perihelion portions of the orbits. Comet C/2014 Q1 (PanSTARRS), with a perihelion distance of only ~0.3 AU, showed the most unusual variation of water production rate with heliocentric distance and the resulting active area variation, indicating that when the comet was within 0.7 AU its activity was dominated by the continuous release of icy grains and chunks, greatly increasing the active sublimation area by more than a factor of 10 beyond what it had at larger heliocentric distances. A possible interpretation suggests that a large fraction of the comet's mass was lost during the apparition.
Comet 21P/Giacobini-Zinner: Water Production Activity over 20 Years with SOHO/SWAN
1985年,21 P/Giacobini-Zinner彗星是第一颗被国际彗星探测器(ICE)探测到的彗星,比1986年的哈雷彗星探测器早了几个月。ICE最初是ISEE-3卫星,设计用于地球附近的磁层测量,并通过月球重力辅助转向穿过彗星的等离子体尾部。这颗彗星在1998年,2005年,2012年和2018年的最后四次出现期间被太阳和日光层观测卫星上的全天空氢莱曼α太阳风各向异性(SWAN)相机观测到。本文比较了Combi等人(2011年)发表的1998年和2005年氢图像计算的产水率,以及2012年和2018年的新观测结果。与一些随着时间推移而褪色的彗星不同,除了2012年的结果中看到的两次爆发外,彗星21 P的活动水平并没有随着时间的推移而发生一致的变化。对所有四次出现的近日点前的产水率与日心距离进行幂律拟合,得到的结果为3.75 x 10^28 x r^-0.28+/-0.4,而对近日点后的产水率,扣除2012年以爆发为主的数据,得到的结果为4.15 x 10^28 x r^-10.2+/-0.9。产生率以s^-1为单位,日心距离以AU为单位。
Kreutz Sungrazers: Summary of Recent Modeling and Orbits of the SOHO Objects
我总结和精简的轨道演化和级联的克鲁兹掠日天体的碎片最近的建模结果。该模型从亚里士多德的彗星开始-其核心被假定为接触双星的祖先-在远日点附近分裂成两个裂片,最后以SOHO矮天体作为分裂过程的最终产物。1843年的大三月彗星(Great March Comet)是星族I的成员,1882年的大九月彗星(Great September Comet)是星族II的成员,被认为是现存质量最大的两颗彗星。我确定,克鲁兹星系目前由9个星群组成,其中之一--与佩雷拉彗星有关--是星群I的一个分支。作为新模型的一部分,克罗伊茨系统的补充是公元363年的日光彗星,由罗马历史学家阿米亚努斯·马塞利努斯记录,以及1041年9月和1138年9月的中国彗星,两者都在何的目录中列出。363年的彗星是第一代碎片,后者--连同1106年的大彗星--是第二代碎片。注意力是针对人口的近日点距离的SOHO掠日者的直方图和这个距离作为一个功能的上升交点的经度的绘图。在未来几十年内,明亮的裸眼克鲁兹掠日者的到来被预测。
Water Production of Interstellar Comet 3I/ATLAS from SOHO/SWAN Observations after Perihelion
University of Michigan(密歇根大学);Finnish Meteorological Institute(芬兰气象局);LATMOS/IPSL UVSQ Université Paris-Saclay, Sorbonne Université, CNRS(巴黎萨克雷大学、索邦大学、法国国家科学研究中心LATMOS/IPSL联合实验室);ACRI-st;LIRA, Observatoire de Paris(巴黎天文台LIRA)
利用SOHO/SWAN观测,研究星际彗星3I/ATLAS水生产率,发现其在近日点后9天的水生产率为3.17 x 10^29 s^-1,随后逐渐下降。
Lowell Observatory(洛厄尔天文台);Department of Astronomy, University of Maryland(马里兰大学天文学系);Center for Space Physics, Boston University(波士顿大学太空物理中心);US Naval Research Laboratory(美国海军研究实验室);Physics Department, United States Naval Academy(美国海军学院物理系);The Thai Astronomical Society(泰国天文学会)
ThermoONet -- a deep learning-based small body thermophysical network: applications to modelling water activity of comets
School of Astronomy and Space Science, Nanjing University(南京大学天文与空间科学学院);Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University(南京大学教育部现代天文与天体物理重点实验室);Shanghai Astronomical Observatory, Chinese Academy of Sciences(中国科学院上海天文台)
Perihelion Asymmetry in the Water Production Rate of the Interstellar Object 3I/ATLAS
School of Atmospheric Sciences, Sun Yat-sen University(中山大学大气科学学院);National Research Council, Institute of Applied Physics ”Nello Carrara” (IFAC–CNR)(意大利国家研究委员会卡拉拉应用物理研究所);Xinjiang Astronomical Observatory, Chinese Academy of Sciences(中国科学院新疆天文台)