The possible dual nature of the asteroid (12499) 1998 FR47

Abstract

We present the R-band lightcurves of the Flora family asteroid (12499) 1998 FR47, obtained in 2022 at two different astronomical sites: Bulgarian National Astronomical Observatory Rozhen (MPC Code 071) and Astronomical Station Vidojevica (MPC Code C89). The quadramodal lightcurves reveal a rotation period of 6.172+/-0.003 h and an amplitude of about 0.44 mag. Using the lightcurve inversion method, with the combination of our dense lightcurves and the sparse data from Gaia DR3, we found the sidereal period, an indication of a retrograde rotation of (12499) and its low-convex resolution shape. Nonetheless, the unusual shape of the quadramodal lightcurve and its additional analysis reveals two possible periods, 3.0834+/-0.0085 h and 4.1245+/-0.0151 h, making the suspect that the asteroid might be a non-synchronised wide binary system. Spectral analysis of the asteroid using data from the GAIA DR3 shows that it is either an M- or an L-type object and maybe a piece of the first planetesimals to form in the Solar System protoplanetary disk. On the other hand, (12499)'s dynamical properties indicate a significantly shorter lifetime. The asteroid lies exactly on the chaotic border of the 7:4 mean motion resonance with Mars (7M:4), alternating between being in and out of it for almost 190 Myrs. During 200 Myrs of integration, (12499) visited other resonances in the Flora family, but it never became a Near Earth Object (NEO). Additional integration of fictive objects from the 7M:4 resonance showed a possibility of transportation to the NEO region already at about 20 Myrs.