TY - JOUR
T1 - Multivariable statistical analysis of spectrophotometry and spectra of (162173) Ryugu as observed by JAXA Hayabusa2 mission
AU - Barucci, M. A.
AU - Hasselmann, P. H.
AU - Fulchignoni, M.
AU - Honda, R.
AU - Yokota, Y.
AU - Sugita, S.
AU - Kitazato, K.
AU - Deshapriya, J. D.P.
AU - Perna, D.
AU - Tatsumi, E.
AU - Domingue, D.
AU - Morota, T.
AU - Kameda, S.
AU - Iwata, T.
AU - Abe, M.
AU - Ohtake, M.
AU - Matsuura, S.
AU - Matsuoka, M.
AU - Hiroi, T.
AU - Nakamura, T.
AU - Kouyama, T.
AU - Suzuki, H.
AU - Yamada, M.
AU - Sakatani, N.
AU - Honda, C.
AU - Ogawa, K.
AU - Hayakawa, M.
AU - Yoshioka, K.
AU - Cho, Y.
AU - Sawada, H.
AU - Takir, D.
AU - Vilas, F.
AU - Hirata, N.
AU - Hirata, N.
AU - Tanaka, S.
AU - Yamamoto, Y.
AU - Yoshikawa, M.
AU - Watanabe, S.
AU - Tsuda, Y.
N1 - Funding Information:
We thank the Haybusa2 JAXA team for their efforts in making the mission successful. Hayabusa2 was developed and built under the leadership of JAXA, with contributions from the DLR and the CNES, and in collaboration with NASA, Nagoya University, University of Tokyo, National Astronomical Observatory of Japan, Aizu University, Kobe University, and other universities, institutes, and companies in Japan. We would also wish to thank all the engineers who contributed to the success of the Hayabusa2 mission, especially T. Masuda, S. Yasuda, K. Matsushima, and T. Ohshima. This study was supported by JSPS International Planetary Network. M.A.B., P.H., J.D.P.D., and M.F. acknowledge funding support from the CNES. D.P. has received funding from the European Union?s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie actions (grant agreement no. 664931).
Funding Information:
Acknowledgements. We thank the Haybusa2 JAXA team for their efforts in making the mission successful. Hayabusa2 was developed and built under the leadership of JAXA, with contributions from the DLR and the CNES, and in collaboration with NASA, Nagoya University, University of Tokyo, National Astronomical Observatory of Japan, Aizu University, Kobe University, and other universities, institutes, and companies in Japan. We would also wish to thank all the engineers who contributed to the success of the Hayabusa2 mission, especially T. Masuda, S. Yasuda, K. Matsushima, and T. Ohshima. This study was supported by JSPS International Planetary Network. M.A.B., P.H., J.D.P.D., and M.F. acknowledge funding support from the CNES. D.P. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie actions (grant agreement no. 664931).
Publisher Copyright:
© M. A. Barucci et al. 2019.
PY - 2019/9/1
Y1 - 2019/9/1
N2 - 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 3σ confidence level, only two groups are evident, while going down to 2σ 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.
AB - 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 3σ confidence level, only two groups are evident, while going down to 2σ 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.
KW - Methods: statistical
KW - Minor planets, asteroids: individual: RYUGU
KW - Techniques: photometric
KW - Techniques: spectroscopic
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U2 - 10.1051/0004-6361/201935851
DO - 10.1051/0004-6361/201935851
M3 - Article
AN - SCOPUS:85071781113
VL - 629
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A13
ER -