Physical parameters and orbital evolution of asteroids in retrograde orbits

Chorzow Astronomical Observatory, 41-500 Chorzow, Poland
e-mail: astrobit@ka.onet.pl

Received: 17 December 2023
Accepted: 28 May 2024

Abstract

Context. We studied the dynamical orbital and physical evolution of all 21 numbered and 13 selected unnumbered asteroids in retrograde orbits.

Aims. Based on all published observations of studied asteroids in retrograde orbits, we computed their starting orbital elements, absolute magnitudes, and diameters, together with the non-gravitational parameters A₂ and da/dt.

Methods. Using publicly available orbital computation methods, we studied the dynamical evolution of orbital elements and the physical parameters of asteroids: rotation period, spin direction, and the non-gravitational parameters A₂.

Results. Lyapunov times (LT) for studied asteroids are short, from 60 to 36 496 yr, with a mean of 5978. Without considering non-gravitational effects, LT is longer: values range from 328 to 63 165 yr, with a mean of 6392. Over the next 10 Myr and beyond, the rotation period of the studied asteroids P decreases by approximately 8%. Moreover, 15% of the clones slow down.

Conclusions. The starting spin distribution becomes flatter, with only one large maximum in the range (0–5) deg containing 279 clones (i.e. approximately 13%). However, the non-gravitational parameter da/dt has a maximum value of around (0–0.04)× 10⁻⁵ au day⁻² .