The Plutino population: An Abundance of contact binaries

TL;DR

This study presents the first lightcurve data for twelve Plutinos, identifying potential contact binaries and estimating that up to 50% of small Plutinos may be contact binaries, highlighting their prevalence in this population.

Contribution

First lightcurve data for twelve Plutinos, identifying potential contact binaries and estimating their high occurrence rate among small Plutinos.

Findings

Up to 40% of Plutinos could be contact binaries.

Potential contact binaries are mostly small with H > 6 mag.

Approximately 50% of small Plutinos may be contact binaries.

Abstract

We observed twelve Plutinos over two separated years with the 4.3m Lowell's Discovery Channel Telescope. Here, we present the first lightcurve data for those objects. Three of them (2014JL$_{80}$, 2014JO$_{80}$, 2014JQ$_{80}$) display a large lightcurve amplitude explainable by a single elongated object, but are most likely caused by a contact binary system due to their lightcurves morphology. These potential contact binaries have rotational periods from 6.3h to 34.9h and peak-to-peak lightcurve variability between 0.6 and 0.8mag. We present partial lightcurves allowing us to constrain the lightcurve amplitude and the rotational period of another nine Plutinos. By merging our data with the literature, we estimate that up to $\sim$40$\%$ of the Plutinos could be contact binaries. Interestingly, we found that all the suspected contact binaries in the 3:2 resonance are small with absolute magnitude H$>$6mag. Based on our sample and the literature, up to $\sim$50$\%$ of the small Plutinos are potential contact binaries.