Letter to the Editor

Dynamics of 2023 FW₁₄, the second L₄ Mars trojan, and a physical characterization using the 10.4 m Gran Telescopio Canarias^⋆

¹ AEGORA Research Group, Facultad de Ciencias Matemáticas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid, Spain
e-mail: rauldelafuentemarcos@gmail.com
² Instituto de Astrofísica de Canarias (IAC), C/ Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
³ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
⁴ Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid, Spain
⁵ Light Bridges S.L., Avda. Alcalde Ramírez Bethencourt 17, 35004 Las Palmas de Gran Canaria, Canarias, Spain
⁶ GRANTECAN, Cuesta de San José s/n, 38712 Breña Baja, La Palma, Spain

Received: 21 February 2024
Accepted: 4 March 2024

Abstract

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 L₅ point and just one at L₄, (121514) 1999 UJ₇. Most L₅ trojans appear to form a collision-induced asteroid cluster, known as the Eureka family. Asteroid 2023 FW₁₄ 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 FW₁₄.

Methods. We carried out an observational study of 2023 FW₁₄ 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 FW₁₄ 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 VF₃₁ does. The Eureka family and 101429 are at the L₅ point. The spectrum of 2023 FW₁₄ is also different from two out of the three spectra in the literature of the other known L₄ trojan, 121514, which are of C-type. The visible spectrum of 2023 FW₁₄ is consistent with that of an X-type asteroid, as is the third spectrum of 121514. Our calculations confirm that 2023 FW₁₄ is the second known L₄ 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 FW₁₄ suggests that regular Mars-crossing asteroids can be captured as temporary Mars trojans.