Issue |
A&A
Volume 688, August 2024
|
|
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Article Number | L7 | |
Number of page(s) | 7 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202450447 | |
Published online | 01 August 2024 |
Letter to the Editor
Size, albedo, and rotational period of the Hayabusa2# target (98943) 2001 CC21
1
LESIA, Université Paris Cité, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, 5 place Jules Janssen, 92195 Meudon, France
e-mail: sonia.fornasier@obspm.fr
2
Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris Cedex 05, France
3
INAF-Osservatorio Astronomico di Roma, 00078 Monte Porzio Catone (Roma), Via Frascati 33, Italy
4
GEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen, 92195 Meudon, France
5
Université Côte d’Azur, CNRS-Lagrange, Observatoire de la Côte d’Azur, CS 34229, 06304 Nice Cedex 4, France
6
School of Physics and Astronomy, University of Leicester, Leicester, UK
7
Institute of Astronomy, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine
8
E. Kharadze Georgian National Astrophysical Observatory, Abastumani, Georgia
9
Samtskhe-Javakheti State University, Akhaltsikhe, Georgia
10
INAF-Astrophysical Observatory of Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
11
IMCCE, Observatoire de Paris, CNRS, PSL Research University, 77 av. Denfert Rochereau, 75014 Paris Cedex, France
12
Astronomical Institute of the Romanian Academy, 5 Cutitul de Argint, 040557, sector 4, Bucharest, Romania
Received:
19
April
2024
Accepted:
17
July
2024
Aims. This study aims to determine the size, albedo, and rotational period of (98943) 2001 CC21, a target of the Hayabusa2 extended mission, using thermal data from the Spitzer Space telescope and ground-based observations.
Methods. The Spitzer data were acquired with the Infrared Spectrograph in the 6–38 μm range, reduced using the Spitzer pipeline, and modeled with the near-Earth asteroid thermal model to determine the asteroid size and albedo. The absolute magnitude and rotational period were determined thanks to new observations carried out at the 3.5 m New Technology Telescope, the 1.2 m Observatoire de Haute Provence, and the 0.7 m Abastumani telescope. Three complete light curves were obtained in 2023 and 2024 at the last-mentioned telescope.
Results. We determine an absolute magnitude of H = 18.94 ± 0.05 and a rotational period of 5.02124±0.00001 hours, with a large light curve amplitude of ∼0.8 mag. at a phase angle of 22°, indicating a very elongated shape with an estimated a/b semiaxis ratio ≥1.7, or a close-contact binary body. The emissivity of 2001 CC21 is consistent with that of silicates, and its albedo is 21.6±1.6%. Finally, the spherical-equivalent diameter of 2001 CC21 is 465±15 m.
Conclusions. The albedo value and emissivity determined here, coupled with results from polarimetry and spectroscopy from the literature, confirm that 2001 CC21 is an S-complex asteroid, and not an L-type one as was previously suggested. The size of 2001 CC21 is less than 500 m, which is smaller than its first size estimation (∼700 m). These results are relevant in preparation of the observing strategy for 2001 CC21 of the Hayabusa2 extended mission.
Key words: methods: data analysis / methods: observational / techniques: photometric / minor planets / asteroids: individual: (98943) 2001 CC21
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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