Multivariable statistical analysis of spectrophotometry and spectra of (162173) Ryugu as observed by JAXA Hayabusa2 mission

被引：17

作者：

Barucci, M. A. ^{[1
]}

Hasselmann, P. H. ^{[1
]}

Fulchignoni, M. ^{[1
]}

Honda, R. ^{[2
]}

Yokota, Y. ^{[2
,3
]}

Sugita, S. ^{[4
,14
]}

Kitazato, K. ^{[5
]}

Deshapriya, J. D. P. ^{[1
]}

Perna, D. ^{[1
,6
]}

Tatsumi, E. ^{[4
,19
]}

Domingue, D. ^{[17
]}

Morota, T. ^{[7
]}

Kameda, S. ^{[8
]}

Iwata, T. ^{[3
]}

Abe, M. ^{[3
,17
]}

Ohtake, M. ^{[3
,17
]}

Matsuura, S. ^{[9
]}

Matsuoka, M. ^{[3
]}

Hiroi, T. ^{[10
]}

Nakamura, T. ^{[11
]}

Kouyama, T. ^{[12
]}

Suzuki, H. ^{[13
]}

Yamada, M. ^{[14
]}

Sakatani, N. ^{[3
]}

Honda, C. ^{[5
]}

Ogawa, K. ^{[15
]}

Hayakawa, M. ^{[3
]}

Yoshioka, K. ^{[4
]}

Cho, Y. ^{[4
]}

Sawada, H. ^{[3
]}

Takir, D. ^{[16
]}

Vilas, F. ^{[17
]}

Hirata, N. ^{[5
,15
]}

Tanaka, S. ^{[3
]}

Yamamoto, Y. ^{[3
]}

Yoshikawa, M. ^{[3
,18
]}

Watanabe, S. ^{[3
,7
]}

Tsuda, Y. ^{[3
,18
]}

机构：

[1] UPMC Univ Paris 06, Univ Paris Diderot, PSL Res Univ,LESIA, Sorbonne Univ,Sorbonne Paris Cite,CNRS,Observ Par, 5 Pl Jules Janssen, F-92195 Meudon, France

[2] Kochi Univ, Kochi 7808520, Japan

[3] JAXA, ISAS, Sagamihara, Kanagawa 2525210, Japan

[4] Univ Tokyo, Tokyo 1130033, Japan

[5] Univ Aizu, Aizu Wakamatsu, Fukushima 9658580, Japan

[6] INAF, Osservatorio Astron Roma, I-00078 Monte Porzio Catone, Italy

[7] Nagoya Univ, Nagoya, Aichi 4648601, Japan

[8] Rikkyo Univ, Tokyo 1718501, Japan

[9] Kwansei Gakuin Univ, Nishinomiya, Hyogo 6628501, Japan

[10] Brown Univ, Providence, RI 02912 USA

[11] Tohoku Univ, Sendai, Miyagi 9808578, Japan

[12] AIST, Tokyo 1350064, Japan

[13] Meiji Univ, Kawasaki, Kanagawa 2148571, Japan

[14] Chiba Inst Technol, Narashino, Chiba 2750016, Japan

[15] Kobe Univ, Kobe, Hyogo 6578501, Japan

[16] Jacobs NASA Johnson Space Ctr, Houston, TX 77058 USA

[17] Planetary Sci Inst, Tucson, AZ 85719 USA

[18] SOKENDAI Grad Univ Adv Studies, Hayama 2400193, Japan

[19] Inst Astrofis Canarias, San Cristobal la Laguna 38205, Spain

来源：

ASTRONOMY & ASTROPHYSICS | 2019年 / 629卷

关键词：

minor planets; asteroids:; individual:; RYUGU; methods: statistical; techniques: photometric; techniques: spectroscopic; NAVIGATION CAMERA ONC; INFLIGHT CALIBRATION; CLASSIFICATION; CENTAURS; TAXONOMY; ONBOARD; OSIRIS;

D O I：

10.1051/0004-6361/201935851

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. Starting from late June 2018, the JAXA asteroid sample return mission Hayabusa2 acquired a large quantity of resolved images and spectra of the surface of the asteroid (162173) Ryugu. Aims. By studying the visible and near-infrared spectral behavior across the surface of Ryugu using a statistical analysis, we aim to distinguish spectral homogeneous groups and to detect the small heterogeneities. This allows us to better constrain the surface composition variations. Methods. In order to isolate and interpret the difference in the asteroid surface spectral behavior, we applied the G-mode multivariate statistical analysis to a set of pixels containing information of (i) the visible ONC-T spectrophotometry, and (ii) the near-infrared NIRS3 spectra thereby obtaining automatic statistical clustering at different confidence levels. Results. The analysis of both ONC-T and NIRS3 data allows us to highlight small spectral variations on the Ryugu surface. At a 3 sigma confidence level, only two groups are evident, while going down to 2 sigma more groups are obtained with differences in spectral slope and band depth. Conclusions. The identified groups have been associated with main morphological surface features. The spectral slope variations that characterize the small groups obtained by ONC-T data analysis, are interpreted as a consequence of space weathering with the presence of more or less fresh material and/or the different grain sizes of the regolith. The variations found analyzing the NIRS3 data are attributed to slightly different contents of hydrated material and different regolith sizes. The distribution on the Ryugu surface of the groups obtained by the analysis of the two instruments indicates a clear spectral dichotomy both between the east and west, and the north and south hemispheres. Small sized regolith grains associated to the redder spectra seem concentrated in the southwestern part of the body.

引用

页数：10

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