Secular Light Curves of NEAs 2201 Oljato, 3200 Phaethon, 99942 Apophis, 162173 Ryugu, 495848, and 6063 Jason

TL;DR

This study applies the Secular Light Curve formalism to six Near-Earth Asteroids, revealing evidence of cometary activity, dormancy, and eclipses, and suggesting many faint comets may still be undiscovered.

Contribution

It demonstrates the effectiveness of SLC analysis in detecting cometary activity and dormancy in NEAs, including new insights into several specific objects.

Findings

2201 Oljato shows significant cometary activity.

3200 Phaethon appears dormant with no current activity.

162173 Ryugu exhibits potential cometary activity.

Abstract

Using the Secular Light Curve (SLC) formalism (Ferr\'in, 2010a, PSS, 58, 365-391), we searched for cometary activity of six NEAS: 2201 Oljato. The SLC exhibits significant cometary activity and evidence of an eclipse. 3200 Phaethon. Is the parent of the Geminid meteor stream and exhibited a faint tail at perihelion in several oppositions. The SLC fails to show cometary activity using a 1995 to 2017 data set, suggesting that we are in the presence of a dormant cometary nucleus. 99942 Apophis. This SLC does not shows evidence of cometary activity, however it shows evidence of an eclipse. The evidence of a double nature is confirmed with Goldstone and Arecibo radar observations. 162173 Ryugu. This NEA is the target of the Hayabusa 2 spacecraft mission. The SLC exhibits an enhancement consistent with cometary activity. It may be possible to confirm or deny this activity by the end of the mission. 495848= 2002 QD7. This NEA shows deviations from a flat distribution near perihelion in 2007 and 2017. However our own observations in 2018 show a bare nucleus, from which we obtain an absolute nuclear magnitude mV(nucleus) = 18.32+-0.03 (using pV=0.04). The equivalent diameter is D=1.43+-0.10 km. 6063 Jason. The SLC of this NEA exhibits low level cometary activity centred at perihelion. The fact that a cursory search for low level active comets among NEAs has uncovered four positive objects out of 6, hints that many more faint comets should exist as yet undetected.