Mini-moons from horseshoes: A physical characterization of 2022 NX1 with OSIRIS at the 10.4 m Gran Telescopio Canarias
| Autor: | Marcos, R. de la Fuente, de Leon, J., Marcos, C. de la Fuente, Licandro, J., Serra-Ricart, M., Cabrera-Lavers, A. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | A&A 670, L10 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202245514 |
| Popis: | Context. The near-Earth orbital space is shared by natural objects and space debris that can be temporarily captured in geocentric orbits. Short-term natural satellites are often called mini-moons. Reflectance spectroscopy can determine the true nature of transient satellites because the spectral signatures of spacecraft materials and near-Earth asteroids (NEAs) are different. The recently discovered object 2022 NX1 follows an Earth-like orbit that turns it into a recurrent but ephemeral Earth companion. It has been suggested that 2022 NX1 could have an artificial origin or be lunar ejecta. Aims. Here, we use reflectance spectroscopy and N-body simulations to determine the nature and actual origin of 2022 NX1. Methods. We carried out an observational study of 2022 NX1, using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias, to derive its spectral class. N-body simulations were also performed to investigate how it reached NEA space. Results. The reflectance spectrum of 2022 NX1 is neither compatible with an artificial origin nor lunar ejecta; it is also different from the V type of the only other mini-moon with available spectroscopy, 2020 CD3. The visible spectrum of 2022 NX1 is consistent with that of a K-type asteroid, although it could also be classified as an Xk type. Considering typical values of the similar albedo of both K-type and Xk-type asteroids and its absolute magnitude, 2022 NX1 may have a size range of 5 to 15 m. We confirm that 2022 NX1 inhabits the rim of Earth's co-orbital space, the 1:1 mean-motion resonance, and experiences recurrent co-orbital engagements of the horseshoe-type and mini-moon events. Conclusions. The discovery of 2022 NX1 confirms that mini-moons can be larger than a few meters and also that they belong to a heterogeneous population in terms of surface composition. Comment: 8 pages, 7 figures, 2 tables, 3 appendixes. Accepted for publication in Astronomy and Astrophysics: Letters |
| Databáze: | arXiv |
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