分裂彗星中彗髮的研究; A Study of Cometary Comae of Split Comets

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題名:	分裂彗星中彗髮的研究;A Study of Cometary Comae of Split Comets
作者:	林忠義;Zhong-Yi Lin
貢獻者:	天文研究所
關鍵詞:	噴流;彗星分裂;彗星;Jets;Comets;Split Comets
日期:	2007-07-02
上傳時間:	2009-09-22 10:12:27 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	從古至今，對於分裂彗星的觀測已經有許多記載。我們可以將彗星分裂現象分為下列四類: 第一類:彗星在分裂後完全消失，沒有遺留下任何殘骸。如 C/1999 S4 (LINEAR) 。第二類 : 彗星經過行星或太陽附近被巨大的潮汐力給撕裂，但卻沒有完全消失。如 D/1993 F2 Shoemaker-Levy 9。第三類: 當彗星經過近日點，彗核就分裂，其所分裂出來的碎核，有些在下一次回歸時仍可以看見。如73P/Schwassmann-Wachmann 3。最後一種是彗星有分裂、爆發現象，但卻沒有觀測到碎片。如 C/2004 Q2 Machholz。目前，雖然有很多分裂彗星的觀測紀錄，但我們卻對這些讓彗星分裂的物理機制不甚了解，因此我們希望由鹿林一米望遠鏡以及興隆兩米光譜觀測來解開這個謎團。這篇論文包含了對彗星 C/2001 A2 LINEAR的光譜分析，我們在此彗星上，發現CN這個氣體分子的光度曲線在最高峰有移動的現象，這似乎與CN噴流有關，這些氣體噴流的來源，可能是一種微小〝CHON〞粒子所造成的，這個假設也證明了彗星 C/2004 Q2 Machholz的噴流為什麼只有在氣體分子（CN和C2）中看見，而在灰塵範圍裡卻看不見。在彗星73P/Schwassmann-Wachmann 3 中，經過影像處理過後，我們發現了一些特殊的彗髮結構 – Coma Wing-，這個結構可能來自於彗星分裂所造成或是由灰塵噴流造成的。最後對於 9P/Tempel 1的聯合觀測，我們利用處於太平洋西岸絕佳的地理位置來填補資料的遺缺，並計算太空船撞擊後所噴出的灰塵雲的擴展速度，我們所得到的結果同樣在東亞觀測的天文學家結果幾乎相同。對於彗星分裂物理機制的研究，我們仍需觀測更多的分裂彗星，這可由天文所參與的夏威夷Pan-Starrs計畫與鹿林即將興建的兩米望遠鏡來執行，我們希望將來可藉由這兩個的計畫來解開彗星分裂之謎。 The splitting of comets has been observed many times. These fragmentation events can be roughly divided into four types. One the split comets disappeared completely (C/1999 S4 LINEAR); two the comet was destroyed during its impact with Jupiter (D/1993 F2 Shoemaker-Levy 9); the third where fragments have remained for a long time (73P/Schwassmann-Wachmann 3); and the fourth the comets suffered several minor fragmentations (C/2004 Q2 Machholz). In this study, we used low-resolution spectrographic and photometry imaging to investigate the activity coma of natural and artificial outburst events. We found that the CN emission of comet 2001 A2 LINEAR displayed remarkable asymmetry, with its intensity peak shiftting to the tailward side by as much as 1000 km away from the center of the dust continuum. There is thus a strong indication that the source of CN distribution was due to the spliting event and not necessarily associated with the central nucleus. A probable release mechanism is associated with the CN jet structure detected in the imaging photometric measurements. Two jets observed for comet C/2004 Q2 Machholz were observed in the coma distributions of C2 and CN of comet Machholz that were not formed in the dust coma. The jets were spiral-like in structure and were angled differently at different observing times. The formation of these jets can be explained by the presence of two active surface regions on the rotating cometary nucleus. Arclets structures are found in comet 73P/Schwassmann-Wachmann 3B after the splitting event and the sources produced a lot of dust and gas particles come from the boulder train (fiant-fragments). Althoughc there were no fragments found in the artificial outburst event, the result still provide us with a much better understanding of the physical structure of the surface of comet Tempel 1.
顯示於類別:	[天文研究所] 博碩士論文

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