Mini-moons from horseshoes: A physical characterization of 2022 NX1 with OSIRIS at the 10.4 m Gran Telescopio Canarias



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Fuente Marcos, Raúl de la and Leon, J. de and Fuente Marcos, Carlos de la and Licandro Goldaracena, Javier and Serra-Ricart, M. and Cabrera-Lavers, A. (2023) Mini-moons from horseshoes: A physical characterization of 2022 NX1 with OSIRIS at the 10.4 m Gran Telescopio Canarias. Astronomy & Astrophysics, 670 . L10(8). ISSN 0004-6361

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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.

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Reseñado en: Sacristán, Enrique. Una miniluna acompañará a la tierra durante las próximas décadas. Retrieved Feb 13, 2023, from

Uncontrolled Keywords:Minor planets, Asteroids, General; Minor planets, Asteroids, Individual, 2022 NX1; Techniques, Spectroscopic; Methods, Numerical; Celestial mechanics
Subjects:Sciences > Physics > Astrophysics
ID Code:76408
Deposited On:26 Jan 2023 16:23
Last Modified:13 Feb 2023 17:13

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