Col-OSSOS: Investigating Outlying Surfaces within the Kuiper Belt's Neutral Coloured Objects

<p>Within the outer Solar System exists the Kuiper belt. This Kuiper belt is made up of many icy planetesimals, the remaining relics of planet-forming bodies that failed to evolve into a planet beyond Neptune. The smaller members of the Kuiper belt (with <em>r</em> mag > 22) generally show linear and featureless spectra. Additionally, due to the dimness of these objects observing their spectra can be particularly difficult. Therefore, broadband photometry is often used to characterise their surfaces. The broadband photometry can be used as a proxy for composition, as it provides enough information to characterise the optical and near-infrared spectral slopes ofthese Kuiper Belt Object (KBO) surfaces.</p> <p>The Colours of the Outer Solar System Origins Survey (Col-OSSOS, Schwamb et al., 2019) took near-simultaneous <em>g-</em>, <em>r-</em> and <em>J-band</em> broadband photometry of a sample of KBOs with unprecedented precision using the Gemini North telescope. As with previous colour surveys (e.g. Tegler et al., 2016), they showed abimodal colour distribution in optical / near-infrared colours for the dynamically ‘hot’ population. We split this colour distribution into the ‘neutral’ coloured population with <em>(</em><em>g−r</em><em>)</em> < 0.75 and the ‘red’ coloured populationwith <em>(</em><em>g−r</em><em>)</em> ≥ 0.75.</p> <p>The preciseness of the colour measurements of Col-OSSOS has allowed the identification of several KBOs with outlying surface colours. These objects separated out from the rest of the neutral cloud in <em>(</em><em>g−r</em><em>)</em> versus <em>(r−J</em><em>)</em> colours, with <em>(</em><em>g−r</em><em>)</em> colour near solar colour. Using the Gemini North telescope in Hawaii we have taken extra photometry in the <em>i</em><em>−</em> and <em>z−</em><em>bands</em> for three of these objects (2013 JE64, 2013 JR65 and 2014 UL225). These additional filter observations will allow us to identify any possible broadband absorption features on these object’s surfaces that may have caused their outlying surface colours. Asteroid interloper 2004 EW95 (Seccull et al., 2018), along with some Jupiter Trojans and C-type asteroids (Bus & Binzel, 2002; DeMeo & Carry,2013) have been shown to have similar near solar neutral surfaces. In this presentation we will report resultsof the <em>griz</em> photometry of 2013 JE64, 2013 JR65 and 2014 UL225. We will make comparisons between these results and the photometry of previously identified outlying KBOs and comment on any possible similarities.</p> <p><strong>References</strong></p> <p>Bus, S. J., & Binzel, R. P. 2002, Icarus, 158, 146<br />DeMeo, F. E., & Carry, B. 2013, Icarus, 226, 723<br />Schwamb, M. E., Bannister, M. T., Marsset, M., et al. 2019, ApJS, 243, 12<br />Seccull, T., Fraser, W. C., Puzia, T. H., Brown, M. E., & Schönebeck, F. 2018, ApJ, Letters, 855, L26<br />Tegler, S. C., Romanishin, W., Consolmagno, G. J., & J., S. 2016, AJ, 152, 210</p>