Homing in for New Year: impact parameters and pre-impact orbital evolution of meteoroid 2014 AA

Abstract

On 2008 October 7, small asteroid 2008 TC3 turned itself into the parent body of the first meteor ever to be predicted before entering the Earth's atmosphere. Over five years later, the 2014 AA event became the second instance of such an occurrence. The uncertainties associated with the pre-impact orbit of 2008 TC3 are relatively small because thousands of observations were made during the hours preceding the actual meteor airburst. In sharp contrast, 2014 AA was only observed seven times before impact and consequently its trajectory is somewhat uncertain. Here, we present a recalculation of the impact parameters -location and timing- of this meteor based on infrasound recordings. The new values and their uncertainties together with Monte Carlo and N-body techniques, are applied to obtain an independent determination of the pre-impact orbit of 2014 AA. Our orbital solution is used to investigate the possible presence of known near-Earth objects (NEOs) moving in similar orbits. Prior to impact, 2014 AA was subjected to a web of overlapping secular resonances and it followed a path similar to those of 2011 GJ3, 2011 JV10, 2012 DJ54, and 2013 NJ4. NEOs in this transient group have their orbits controlled by close encounters with the Earth-Moon system at perihelion and Mars at aphelion, perhaps constituting a dynamical family. Extensive comparison with other studies is also presented.