近地小行星之起源與演化;Origin and Evolution of Near-Earth Asteroids

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/62388

Title:	近地小行星之起源與演化;Origin and Evolution of Near-Earth Asteroids
Authors:	阿部新助
Contributors:	國立中央大學天文研究所
Keywords:	物理
Date:	2012-12-01
Issue Date:	2014-03-17 11:31:40 (UTC+8)
Publisher:	行政院國家科學委員會
Abstract:	研究期間：10108~10207;Small bodies of the solar system such as asteroids and comets represent both a potentially rich resource for future space exploration and a threat to the very existence of humankind on Earth due to impact risks. Near Earth Objects (NEOs) have the advantage of being much more accessible for scientific research and space missions than small bodies in the outer solar system beyond Jupiter. A study of NEOs will provide crucial evidences to answer the key questions; (a) How are asteroids and meteorites (and meteor showers) related to each other; compositions and their orbital associations? (b) What are the main characteristics of near-Earth asteroids’ population, size, shape, and rotation? The Panoramic Survey Telescope And Rapid Response System “Pan-STARRS” is a project, initiated by the Institute for Astronomy, University of Hawaii, to repeatedly survey covering three quarters of the entire sky. Since May 2010 the prototype single-mirror telescope “Pan-STARRS-1 (PS1)” has been operating on Mt. Haleakala in Hawaii. The PS1 Science Consortium in 4 countries including National Central University Taiwan is undertaking its 3.5-years scientific research program until Oct 2013. Solar System moving objects such as asteroids and comets are crucial targets for the PS1 project. As of April 2011, about 340 NEOs have been detected and 68 of them were newly discovered asteroids. National Central University (NCU) team has established our own follow-up procedure using TenagraII 32”(~81cm) remote telescope in Arizona, USA. My (Taiwanese) regular contribution to the discovery of PS1 NEOs will surely increase until Oct 2013, the end of PS1 operation. The expected discovery rate of new NEO is about 10-30 per month by PS1 telescope. In order to keep our contribution (follow-up observations of ~50% of PS1 NEOs), I plan to use TenagraII remote telescope about 1 hour every 3 night throughout a year. About 550,000 asteroids were discovered to date and ~7200 of them are NEOs and ~ 1,100 are PHOs (Potentially Hazardous Objects), a subset of NEOs closely approach Earth’s orbit. However, connection between NEOs/PHAs and Earth impactors such as meteorites or meteors are still under debate due to observational biases, large uncertainties of orbital elements and chaotic orbital evolutions due to perturbations by planet gravity and thermal effect called Yarkovsky effect. PS1 NEOs provide more opportunities to investigate the NEO family (which shares nearly identical orbit) and its connection to meteorites. The PS1 provides not only ‘discovered NEOs’ but also ‘known NEOs’ that have observed before. Thus, the orbit of re-observed known NEO by PS1 enables to carry out the minor thermal force “Yarkovsky effect”; absorbed thermal energy during the day is radiated away when the heated surface rotates to afternoon side. This unbalanced thermal radiation produces a tiny acceleration that gradually changes the asteroid’s orbit. In order to understand chaotic orbital evolution, mathematical integrations of orbital elements of NEOs considering the Yarkovsky effect are carried out using the computational cluster.
Relation:	財團法人國家實驗研究院科技政策研究與資訊中心
Appears in Collections:	[Graduate Institute of Astronomy] Research Project

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