Two Color Populations of Kuiper Belt and Centaur Objects and the Smaller Orbital Inclinations of Red Centaur Objects

Abstract

We present new optical colors for 28 Kuiper Belt objects (KBOs) and 35 Centaur objects measured with the 1.8 m Vatican Advanced Technology Telescope and the 4.3 m Discovery Channel Telescope. By combining these new colors with our previously published colors, we increase the sample size of our survey to 154 objects. Our survey is unique in that the uncertainties in our color measurements are less than half the uncertainties in the color measurements reported by other researchers in the literature. Small uncertainties are essential for discerning between a unimodal and a bimodal distribution of colors for these objects as well as detecting correlations between colors and orbital elements. From our survey, it appears red Centaurs have a broader color distribution than gray Centaurs. We find red Centaurs have a smaller orbital inclination angle distribution than gray Centaurs at the 99.3% confidence level. Furthermore, we find that our entire sample of KBOs and Centaurs exhibits bimodal colors at the confidence level. KBOs and Centaurs with H V > 7.0 have bimodal colors at the 99.96% confidence level and KBOs with H V < 6.0 have bimodal colors at the 96% confidence level.

Col-OSSOS: z-Band Photometry Reveals Three Distinct TNO Surface Types

“…Given the size of our sample, unsurprisingly, we do not find statistically significant evidence of bi-modality. As this topic is discussed quite thoroughly in other works with samples more appropriate to test the existence of bi-modality, we adopt the accepted conclusion that the excited populations possess two compositional classes as evidenced by their bimodal optical colors (Tegler & Romanishin 1998;Peixinho et al 2003Peixinho et al , 2012Peixinho et al , 2015Tegler et al 2003Tegler et al , 2016Doressoundiram et al 2007;Wong & Brown 2017). However, Figure 1 indicates that dividing these objects requires more than a simple optical color cut; we use a surface model based on to describe the color range occupied by two dynamically excited TNOs compositional classes.…”

“…TNOs, in general, have red optical colors in g-, r-, and i-bands; even the "neutral" TNO surfaces, sometimes referred to as "blue" in the literature, are slightly redder than solar. It is well accepted that the small dynamically excited TNOs and Centaurs exhibit a bimodal color distribution, with red and neutral classes (e.g., Tegler & Romanishin 1998;Peixinho et al 2003Peixinho et al , 2012Peixinho et al , 2015Tegler et al 2003Tegler et al , 2016Wong & Brown 2017).…”

Light curves of ten Centaurs from K2 measurements

“…Peixinho et al, 2012Peixinho et al, , 2015 and the two colour groups correspond to two different average albedos (Lacerda et al, 2014;Farkas-Takács et al, 2018). For our targets we have colour information for 2012 VU 85 and 2002 KY 14 (Tegler et al, 2016;Wong et al, 2019), but as mentioned above, 2002 KY 14 has a reliable size estimate from radiometry. For 2012 VU 85 Tegler et al (2016) obtained V-R = 0.63±0.04 mag, and with this colour 2012 VU 85 is in the 'bright-red' group identified by Lacerda et al (2014) which has a mean albedo of p V = 0.16±0.08.…”

“…For our targets we have colour information for 2012 VU 85 and 2002 KY 14 (Tegler et al, 2016;Wong et al, 2019), but as mentioned above, 2002 KY 14 has a reliable size estimate from radiometry. For 2012 VU 85 Tegler et al (2016) obtained V-R = 0.63±0.04 mag, and with this colour 2012 VU 85 is in the 'bright-red' group identified by Lacerda et al (2014) which has a mean albedo of p V = 0.16±0.08. We used this value to obtain the effective diameter of 2012 VU 85 from the absolute magnitude.…”

Cometary Activity Discovered on a Distant Centaur: A Nonaqueous Sublimation Mechanism

“…We compared our colors of g−r = 0.80±0.024 and r−i = 0.39±0.024 to SDSS reported Solar colors of g−r = 0.44±0.02 and r−i = 0.11±0.02 1 . Centaur colors are often reported in Johnson B-R colors (see e.g., Tegler et al 2016), so we computed the B − R color for 2014 OG 392 via Jester et al (2005) transformations. We found B-R = 1.64 ± 0.4 which is about one magnitude redder than the Sun, and red according to the classification system of Tegler et al (2016) (see discussion in Section 9).…”