轨道周期测定作为研究掠日彗星谱系的不可或缺工具
Orbital-Period Determination As an Indispensable Tool to Study the Pedigree of a Sungrazing Comet
AI总结：
该研究针对约4500颗克鲁兹掠日彗星中仅5颗轨道周期测定精度较高的问题，提出通过分析最后观测得到的轨道周期来过滤活动或核碎裂影响，以确定上一次近日点时间，为研究掠日彗星谱系提供关键方法。
AI中文摘要：
在已知的约4500颗克鲁兹掠日彗星中，仅C/1882 R1、C/1963 R1、C/1965 S1、C/2011 W3和C/2026 A1的轨道周期测定精度优于±20年。本文阐述了一系列涉及轨道周期测定的有趣问题的解决方案：一种虽需大量计算但十分有效的方法是，详细研究由最后一次观测得到的轨道周期，以此过滤彗星活动（如C/2026 A1的情况）或核碎裂（如C/1965 S1的情况）的影响，从而可靠地确定上一次近日点的时间，这是探究掠日彗星谱系的关键。经验表明，只有C/1882 R1的原始彗核或其主要碎片B这类质量极大的天体，才不受此类效应影响；而彗核在近日点后不久解体（如C/2011 W3的情况）或仅在近日点后被观测（如C/1963 R1的情况）的掠日彗星，则会带来不同的问题。当标准方法失效或结果不确定时，可利用已证实的掠日彗星运动受微小摄动影响的高度敏感性来解决问题。
英文摘要：
Among some 4500 Kreutz sungrazers known, the orbital period has been established to better than about +/-20 years only for C/1882 R1, C/1963 R1, C/1965 S1, C/2011 W3, and C/2026 A1. I describe solutions to a range of intriguing problems involving the orbital-period determination. A helpful, but computer-intensive routine is a detailed investigation of derived orbital periods as a function of the last observation used, which allows one to filter out effects of activity (the case of C/2026 A1) or nuclear fragmentation (the case of C/1965 S1) and thereby reliably evaluate the time of the previous perihelion, a cornerstone in the quest for a sungrazer's pedigree. Experience shows that only very massive objects, such as the original nucleus of C/1882 R1 or its main fragment B are immune to effects of this kind. Different problems are presented by a sungrazer whose nucleus falls apart shortly after perihelion (the case of C/2011 W3) or by one observed only after perihelion (the case of C/1963 R1). The documented high sensitivity of the derived orbital period to minor perturbations of a sungrazing comet's motion is exploited to advantage when the standard approach does not work or yields inconclusive results.
