Issue |
A&A
Volume 688, August 2024
|
|
---|---|---|
Article Number | L23 | |
Number of page(s) | 7 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202450586 | |
Published online | 13 August 2024 |
Letter to the Editor
Asteroid (4337) Arecibo: Two ice-rich bodies forming a binary
Based on Gaia astrometric data
1
IMCCE, Paris Observatory, CNRS, Univ. PSL, Sorbonne Université, Univ. Lille, 77 Av. Denfert-Rochereau, 75014 Paris, France
2
Institut Polytechnique des Sciences Avancées IPSA, 63b Bd. de Brandebourg, 94200 Ivry-sur-Seine, France
Received:
2
May
2024
Accepted:
18
July
2024
Context. Binary asteroids are present in all populations of the Solar System, from near-Earth to trans-Neptunian regions. As is true for the small Solar System bodies (SSSBs), binary asteroids generally offer valuable insights into the formation of the Solar System, as well as its collisions and dynamic evolution. In particular, the binaries provide fundamental quantities and properties of these SSSBs, such as mass, angular momentum, and density, all of which are often hidden. The direct measurement of densities and porosities is of great value in revealing the gravitational aggregates and icy bodies that form the asteroid-comet continuum.
Aims. Several observation techniques from space and ground-based platforms have provided many results in this regard. Here we show the value of the Gaia mission and its high-precision astrometry for analysing asteroid binaries and for individually deriving the masses of the components.
Methods. We focus on the binary asteroid (4337) Arecibo, a member of the Themis family. We analysed the astrometry obtained in the Gaia FPR catalogue release, and performed orbital fitting for both the heliocentric orbit of the system and the relative orbit of the binary components.
Results. We obtain an estimation of the component masses and their flux ratio, and derive bulk densities ρ1 ≈ 1.2 and ρ2 ≈ 1.6 for the primary and the secondary, respectively. The results are consistent with an ice-rich body in the outer main belt. They also show a significantly denser secondary or a less closely packed primary. Constraints on these densities and on macroscopic porosities are nevertheless limited by our poor knowledge of the sizes of the components. Observations of future mutual events, and of stellar occultations predicted in 2024–2025, will be essential for improving our knowledge of this system and its formation.
Key words: methods: data analysis / astrometry / minor planets / asteroids: individual: (4337) Arecibo
© 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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