Astrometry, orbit determination, and thermal inertia of the Tianwen-2 target asteroid (469219) Kamo`oalewa
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866916655869722624 |
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| author | Fenucci, Marco Novaković, Bojan Zhang, Pengfei Carbognani, Albino Micheli, Marco Faggioli, Laura Gianotto, Francesco Ocaña, Francisco Föhring, Dora Cano, Juan Luis Conversi, Luca Moissl, Richard |
| author_facet | Fenucci, Marco Novaković, Bojan Zhang, Pengfei Carbognani, Albino Micheli, Marco Faggioli, Laura Gianotto, Francesco Ocaña, Francisco Föhring, Dora Cano, Juan Luis Conversi, Luca Moissl, Richard |
| contents | Context. (469219) Kamo`oalewa is a small near-Earth asteroid, which is currently a quasi-satellite of the Earth. Lightcurve measurements also reveal a rotation period of only about 30 minutes. This asteroid has been selected as the target of the Tianwen-2 sample-return mission of the China National Space Administration.
Aims. The first goal of this paper is to observe and improve the orbit determination of (469219) Kamo`oalewa, and better determine the Yarkovsky effect acting on it. The second goal is to estimate the thermal inertia of the asteroid, taking advantage of an improved Yarkovsky effect determination.
Methods. Our observational campaign imaged the asteroid from the Loiano Astronomical Station and from the Calar Alto Observatory, in March 2024. We also accurately re-measured a precovery detection from the Sloan Digital Sky Survey from 2004. New astrometry was later used in a 7-dimensional orbit determination, aimed at estimating both the orbital elements and the Yarkovsky effect. Thermal inertia is later studied by using the ASTERIA, a new method that is suitable to estimate thermal inertia of small asteroids.
Results. We detected a semi-major axis drift of $(-67.35 \pm 4.70) \times 10^{-4}$ au My$^{-1}$ due to the Yarkovsky effect, with a high signal-to-noise ratio of 14. The new orbit solution also significantly reduced the position uncertainty for the arrival of the Tianwen-2 spacecraft. By using different models for the physical parameters of Kamo`oalewa, the ASTERIA model estimated the thermal inertia at $Γ= 150^{+90}_{-45}$ J m$^{-2}$ K$^{-1}$ s$^{-1/2}$ or $Γ= 181^{+95}_{-60}$ J m$^{-2}$ K$^{-1}$ s$^{-1/2}$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_13222 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Astrometry, orbit determination, and thermal inertia of the Tianwen-2 target asteroid (469219) Kamo`oalewa Fenucci, Marco Novaković, Bojan Zhang, Pengfei Carbognani, Albino Micheli, Marco Faggioli, Laura Gianotto, Francesco Ocaña, Francisco Föhring, Dora Cano, Juan Luis Conversi, Luca Moissl, Richard Earth and Planetary Astrophysics Instrumentation and Methods for Astrophysics Context. (469219) Kamo`oalewa is a small near-Earth asteroid, which is currently a quasi-satellite of the Earth. Lightcurve measurements also reveal a rotation period of only about 30 minutes. This asteroid has been selected as the target of the Tianwen-2 sample-return mission of the China National Space Administration. Aims. The first goal of this paper is to observe and improve the orbit determination of (469219) Kamo`oalewa, and better determine the Yarkovsky effect acting on it. The second goal is to estimate the thermal inertia of the asteroid, taking advantage of an improved Yarkovsky effect determination. Methods. Our observational campaign imaged the asteroid from the Loiano Astronomical Station and from the Calar Alto Observatory, in March 2024. We also accurately re-measured a precovery detection from the Sloan Digital Sky Survey from 2004. New astrometry was later used in a 7-dimensional orbit determination, aimed at estimating both the orbital elements and the Yarkovsky effect. Thermal inertia is later studied by using the ASTERIA, a new method that is suitable to estimate thermal inertia of small asteroids. Results. We detected a semi-major axis drift of $(-67.35 \pm 4.70) \times 10^{-4}$ au My$^{-1}$ due to the Yarkovsky effect, with a high signal-to-noise ratio of 14. The new orbit solution also significantly reduced the position uncertainty for the arrival of the Tianwen-2 spacecraft. By using different models for the physical parameters of Kamo`oalewa, the ASTERIA model estimated the thermal inertia at $Γ= 150^{+90}_{-45}$ J m$^{-2}$ K$^{-1}$ s$^{-1/2}$ or $Γ= 181^{+95}_{-60}$ J m$^{-2}$ K$^{-1}$ s$^{-1/2}$. |
| title | Astrometry, orbit determination, and thermal inertia of the Tianwen-2 target asteroid (469219) Kamo`oalewa |
| topic | Earth and Planetary Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2502.13222 |