Link between the Potentially Hazardous Asteroid (86039) 1999 NC43 and the Chelyabinsk meteoroid tenuous

TL;DR

This study investigates the potential link between the Chelyabinsk meteoroid and asteroid 1999 NC43 through orbit, composition, and rotation analysis, ultimately finding the connection unlikely based on statistical, compositional, and rotational evidence.

Contribution

The paper provides a comprehensive statistical, compositional, and rotational analysis to evaluate the proposed link between Chelyabinsk and 1999 NC43, concluding the connection is improbable.

Findings

Orbit of Chelyabinsk is close to 1999 NC43 with low chance coincidence.

Compositional analysis shows Chelyabinsk and 1999 NC43 differ in mineralogy.

1999 NC43 exhibits tumbling rotation with non-principal axis wobbling.

Abstract

We explored the statistical and compositional link between Chelyabinsk meteoroid and potentially hazardous asteroid (86039) 1999 NC43 to investigate their proposed relation proposed by Borovi\v{c}ka et al. (2013). Using detailed computation we confirm that the orbit of the Chelyabinsk impactor is anomalously close to 1999 NC43. We find about (1-3) x 10-4 likelihood of that to happen by chance. Taking the standpoint that the Chelyabinsk impactor indeed separated from 1999 NC43 by a cratering or rotational fission event, we run a forward probability calculation, which is an independent statistical test. However, we find this scenario is unlikely at the about (10-3 -10-2) level. We also verified compositional link between Chelyabinska and 1999NC43. Mineralogical analysis of Chelyabinsk (LL chondrite) and (8) Flora (the largest member of the presumed LL chondrite parent family) shows that their olivine and pyroxene chemistries are similar to LL chondrites. Similar analysis of 1999 NC43 shows that its olivine and pyroxene chemistries are more similar to L chondrites than LL chondrites (like Chelyabinsk). We also took photometric observations of 1999 NC43 over 54 nights during two apparitions (2000, 2014). The lightcurve of 1999 NC43 resembles simulated lightcurves of tumblers in Short-Axis Mode with the mean wobbling angle 20-30 deg. While, a mechanism of the non-principal axis rotation excitation is unclear, we can rule out the formation of asteroid in disruption of its parent body as a plausible cause, as it is unlikely that the rotation of an asteroid fragment from catastrophic disruption would be nearly completely halted. Considering all these facts, we find the proposed link between the Chelyabinsk meteoroid and the asteroid 1999 NC43 to be unlikely.