Dynamics of 2023 FW 14 , the second L 4 Mars trojan, and a physical characterization using the 10.4 m Gran Telescopio Canarias

• Published in: Astronomy and astrophysics (Berlin) 2024-03, Vol.683, p.L14
• Main Authors: de la Fuente Marcos, R., de León, J., de la Fuente Marcos, C., Alarcon, M. R., Licandro, J., Serra-Ricart, M., Geier, S., Cabrera-Lavers, A.
• Format: Article
• Language: English
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202449688

Context. Known Mars trojans could be primordial small bodies that have remained in their present-day orbits for the age of the Solar System. Their orbital distribution is strongly asymmetric; there are over a dozen objects at the L 5 point and just one at L 4 , (121514) 1999 UJ 7 . Most L 5 trojans appear to form a collision-induced asteroid cluster, known as the Eureka family. Asteroid 2023 FW 14 was recently discovered and it has a robust orbit determination that may be consistent with a Mars trojan status. Aims. Our aim is determine the nature and dynamical properties of 2023 FW 14 . Methods. We carried out an observational study of 2023 FW 14 to derive its spectral class using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias. We investigated its possible trojan resonance with Mars using direct N -body simulations. Results. The reflectance spectrum of 2023 FW 14 is not compatible with the olivine-rich composition of the Eureka family; it also does not resemble the composition of the Moon, although (101429) 1998 VF 31 does. The Eureka family and 101429 are at the L 5 point. The spectrum of 2023 FW 14 is also different from two out of the three spectra in the literature of the other known L 4 trojan, 121514, which are of C-type. The visible spectrum of 2023 FW 14 is consistent with that of an X-type asteroid, as is the third spectrum of 121514. Our calculations confirm that 2023 FW 14 is the second known L 4 Mars trojan although it is unlikely to be primordial; it may remain in its present-day “tadpole” path for several million years before transferring to a Mars-crossing orbit. It might be a fragment of 121514, but a capture scenario seems more likely. Conclusions. The discovery of 2023 FW 14 suggests that regular Mars-crossing asteroids can be captured as temporary Mars trojans.