# Color variations of Comet C/2013 UQ4 (Catalina)

## TL;DR

This study observes rapid color changes in Comet C/2013 UQ4 (Catalina), revealing a chemically heterogeneous dust coma with at least two distinct components, and finds no significant gaseous CO/CO2 emissions.

## Contribution

It provides the first detailed analysis of rapid color variation and dust composition heterogeneity in Comet Catalina using optical and infrared observations.

## Key findings

- Color slope varies significantly over two days.
- Comet classified as dust-rich with no significant CO/CO2 emissions.
- Comet's dust coma is chemically heterogeneous with at least two components.

## Abstract

We report observations of color in the inner coma of Comet C/2013 UQ4 (Catalina) with the broadband B and R filters. We find significant temporal variations of the color slope, ranging from -12.67 $\pm$ 8.16 \% per 0.1~$\mu$m up to $35.09 \pm 11.7$ \% per 0.1~$\mu$m.It is significant that the comet changes color from red to blue over only a two-day period. Such dispersion cannot be characterized with an average color slope. We also observe Comet C/2013 UQ4 (Catalina) in infrared using Spitzer and find no significant CO/CO$_{2}$ gaseous species in its coma. Therefore, we classify Comet C/2013 UQ4 (Catalina) as a dust-rich comet and attribute the measured color slope to its dust. We analyze the color slope using the model of agglomerated debris particles and conclude that the C/2013 UQ4 coma was chemically heterogeneous, consisting of at least two components. The first component producing the bluest color is consistent with Mg-rich silicates. There are three different options for the second component producing the reddest color. This color is consistent with either Mg-Fe silicates, kerogen type II, or organic matter processed with a low dose of UV radiation.

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Source: https://tomesphere.com/paper/1706.01228