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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/76696


    Title: Time-Series Study of Asteroid using CNEOST in Xuyi Observation Station, Purple Mountain Observatory, China
    Authors: 葉庭碩;Yeh, Ting-Shuo
    Contributors: 天文研究所
    Keywords: 小行星;自轉週期;巡天;Asteroids;Rotation period;Sky survey
    Date: 2018-08-22
    Issue Date: 2018-08-31 11:33:40 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 小行星的幾個重要的物理性質可以從光變曲線中取得,例如小行星的旋轉狀態(包含自轉週期以及自轉軸的指向等等)、形狀、內部結構和分類等等。此外,透過統計小行星的自旋狀態,我們還可以了解究竟有哪些機制會影響到小行星的自轉(例如碰撞,潮汐力和Yarkovsky–O’Keefe–Radzievskii–Paddack效應)。要對上述問題進行全面研究,便需要大量的小行星旋轉樣本。
    因此,我們透過台灣及中國的兩岸交流合作計畫,與中國紫金山天文台(PMO)合作,,使用其盱眙觀測站的「中國近地天體觀測望遠鏡」(CNEOST)蒐集大量小行星的光變曲線。這次合作的主要目標是發現快速自旋小行星(SFR),以及做小行星自旋頻率分布之統計。我們總共進行了兩次的合作巡天:(a)在2017年2月27日至3月2日期間以8分鐘的間距進行約40平方度天區的巡天,以及(b)在2018年3月9日至12日期間以10分鐘的間距,進行約50平方度天區的巡天。在第一次的巡天中,我們從1650條光曲線中獲得了217個具有高可信賴度的旋轉週期,在第二次測量中,則從2872條光曲線找出了332個具有高可信賴度的旋轉週期。
    這兩次的巡天所找到的小行星,幾乎全都是主帶小行星,此外我們也找到一些希爾達小行星和木星的特洛伊小行星。總共獲得了222個U=3的小行星旋轉週期,以及327個U=2的旋轉週期。在U=3的小行星中,我們發現了一個可能的超快自旋小行星,U = 2的小行星則有18個可能的目標。此外,我們發現了一個可能的雙小行星系統,(2280)Kunikov,在LCDB的資料中,(2280)Kunikov有著相對較長的旋轉週期,直徑約6.5公里。這顆小行星的光變曲線擁有類似於食雙星的特徵,例如相對較大的光變振幅,以及較尖的光變曲線。為了確定(2280)Kunikov是否真的為雙小行星系統,我們需要對其做後續的觀察。
    我們針對這次位於主小行星帶中不同位置的小行星,進行了不同大小的自旋速度分佈統計。然而結果顯示,自旋率分佈與小行星的大小和位置並沒有很明顯的關係。;Several important physical properties of asteroid can be derived from light curve, such as rotation sense (e.g. rotation period and spin pole orientation), general shape (e.g., axis ratio estimated form light curve amplitude and shape model from light curve inversion), interior structure (i.e., the spin-rate limits of rubble-pile asteroids), and taxonomic type (e.g., phase-curve relation). Moreover, the statistics on asteroid spin rate and pole orientation are also important to understand how rotational states was affected by various mechanisms (e.g., mutual collision, tidal force and the Yarkovsky–O’Keefe–Radzievskii–Paddack effect). To have a comprehensive study on the aforementioned questions, it relies on a large sample of asteroid rotation.
    Therefore, we initiated our cross-strait bilateral collaboration with the Purple Mountain Observatory (PMO) to collect asteroid light curves using the CNEOST (Chinese Near-Earth Object Survey Telescope) at Xuyi Observation Station. The main goals of this collaboration are to discover super-fast rotators (SFRs) and to carry out asteroid spin-rate distribution. Two campaigns have been conducted: (a) a survey of ~40 deg2 using 8-min cadence during February 27 – March 2 2017, and (b) a survey of ~50 deg2 using 10-min cadence during March 9 – 12 2018. We obtained 217 reliable rotation periods out of 1650 light curves in the first survey and 332 reliable rotation periods out of 2872 light curves in the second survey.
    Almost all asteroids in our samples are the Main-Belt asteroids, and we detect some Hilda asteroids and Jupiter Trojans. In total, we obtained 222 rotation periods of U=3 (i.e. the quality code given by different reliability of light curve) and 327 of U=2, and among them, there are 1 SFR candidates of U=3 and 18 SFR candidates of U=2. Moreover, we found a binary candidate, asteroid (2280) Kunikov, which has a relatively long rotation period listed in the LCDB and is ~6.5 km in diameter. This asteroid shows a light curve with a large amplitude and a sharp similar to the feature of mutual eclipse. To confirm the binarity of (2280) Kunikov, we need more follow-up observations.
    We carried out the spin-rate distributions of asteroids of different sizes at different locations in main belt. The result shows that there is no obvious relation between the spin-rate distribution and the size and location of asteroid.
    Appears in Collections:[天文研究所] 博碩士論文

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