日本地球惑星科学連合2018年大会

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セッション記号 P (宇宙惑星科学) » P-PS 惑星科学

[P-PS03] 太陽系小天体研究:現状の理解と将来の展望

2018年5月23日(水) 13:45 〜 15:15 A02 (東京ベイ幕張ホール)

コンビーナ:石黒 正晃(ソウル大学物理天文学科)、中本 泰史(東京工業大学)、荒川 政彦(神戸大学大学院理学研究科、共同)、安部 正真(宇宙航空研究開発機構宇宙科学研究所)、座長:Ishiguro Masateru(Seoul National University)

14:15 〜 14:30

[PPS03-03] Polarimetric research on S- and Q-type Near-Earth Asteroids

*Jooyeon Geem1Masateru Ishiguro1Yoonsoo P. Bach1Daisuke Kuroda2Hiroyuki Naito3Yoonyoung Kim1Yuna G. Kwon1Masataka Imai4Kiyoshi Kuramoto4Makoto Watanabe5Ryo Okazaki6 (1.Department of Astronomy, Seoul National University、2.Okayama Astrophysical Observatory, National Astronomical Observatory of Japan、3.Nayoro Observatory、4.Department of Cosmosciences, Graduate School of Science, Hokkaido University、5.Faculty of Science Department of Applied Physics, Okayama University of Science、6.Hokkaido University of Education, Asahikawa Campus)

キーワード:Asteroid, Polarimetry

Polarimetry is a useful technique for investigating the physical properties of the target’s surface. The dependency of the polarization degree on the phase angle (the angle between Sun-target-the Earth, α) produces the polarization curve which contains parameters, for example, the minimum and maximum polarization degrees occurring at the phase angle α~20 degree and α~100 degree. In particular, polarimetric observations at large α provide valuable information regarding the regolith size, which is difficult to be determined via other observation techniques (i.e., photometry and spectroscopy).

Despite the advantages, however, only a few asteroids were observed with polarimetric devices at the large phase angles. The most asteroids have been studied at the low phase angles (α <~ 20 degree) due to the unfavorable geometric condition (i.e., they exist outside of Earth orbit). Here, we present our new polarimetric research of Near-Earth-Asteroids (NEAs) observed at the large phase angle. We focus on S- and Q-type asteroids in this presentation. We thus conducted observations of asteroids: (331471) 1984 QY1, (90075) 2002 VU94, and (66391) 1999 KW4 using Pirka Telescope (Nayoro Observatory, Hokkaido University) at the phase angle α~100 degree, which allows us to get maximum polarization degrees of these objects. Based on the observational results together with two objects ((1566) Icarus and (4179) Toutatis in reference papers [1], [2]), we will discuss the implication of the grain size on their surfaces.

[1] Ishiguro et al., (1997), PASJ.
[2] Ishiguro et al., (2017), AJ.