Near-Infrared Spectroscopy Of The Nucleus Of Low-Activity Comet P/2016 BA$_{14}$ During Its 2016 Close Approach

TL;DR

This study presents near-infrared observations and thermal modeling of comet P/2016 BA$_{14}$, revealing its nucleus properties and suggesting it is a typical dormant comet, aiding future spacecraft mission planning.

Contribution

First detailed near-infrared spectral and thermal analysis of P/2016 BA$_{14}$, providing insights into its surface properties and activity state.

Findings

BA$_{14}$ has a low geometric albedo of 0.01-0.03.

Its reflectance spectrum is red and linear in H and K bands.

Thermal modeling suggests typical NEO beaming parameters.

Abstract

The Near-Earth Comet P/2016 BA$_{14}$ (PanSTARRS) is a slow-rotatating nearly-dormant object, a likely dynamical twin of 252P/LINEAR, and was recently shown to have a mid-infrared spectrum very dissimilar to other comets. BA$_{14}$ also recently selected one of the back-up targets for the ESA's \textit{Comet Interceptor}, so a clearer understanding of BA$_{14}$'s modern properties would not just improve our understanding of how comets go dormant, but could also aid planning for a potential spacecraft visit. We present observations of BA$_{14}$ taken on two dates during its 2016 Earth close approach with the NASA Infrared Telescope Facility, both of which are consistent with direct observations of its nucleus. The reflectance spectrum of BA$_{14}$ is similar to 67P/Churyumov-Gerasimenko, albeit highly phase-reddened. Thermal emission contaminates the reflectance spectrum at longer wavelengths, which we correct with a new Markov Chain Monte Carlo thermal modeling code. The models suggest $BA_{14}$'s visible geometric albedo is $p_V=0.01-0.03$, consistent with radar observations, its beaming parameter is typical for NEOs observed in its geometry, and its reflectrance spectrum is red and linear throughout H and K band. It appears very much like a "normal" comet nucleus, despite its mid-infrared oddities. A slow loss of fine grains as the object's activity diminished might help to reconcile some of the lines of evidence, and we discuss other possibilities. A spacecraft flyby past BA$_{14}$ could get closer to the nucleus than with a more active target, and we highlight some science questions that could be addressed with a visit to a (nearly-)dormant comet.