THE CANADA-FRANCE ECLIPTIC PLANE SURVEY—L3 DATA RELEASE: THE ORBITAL STRUCTURE OF THE KUIPER BELT

Abstract

We report the orbital distribution of the trans-Neptunian comets discovered during the first discovery year of the Canada–France Ecliptic Plane Survey (CFEPS). CFEPS is a Kuiper Belt object survey based on observations acquired by the Very Wide component of the Canada–France–Hawaii Telescope Legacy Survey (LS-VW). The first year's detections consist of 73 Kuiper Belt objects, 55 of which have now been tracked for three years or more, providing precise orbits. Although this sample size is small compared to the world-wide inventory, because we have an absolutely calibrated and extremely well-characterized survey (with known pointing history) we are able to de-bias our observed population and make unbiased statements about the intrinsic orbital distribution of the Kuiper Belt. By applying the (publically available) CFEPS Survey Simulator to models of the true orbital distribution and comparing the resulting simulated detections to the actual detections made by the survey, we are able to rule out several hypothesized Kuiper Belt object orbit distributions. We find that the main classical belt's so-called 'cold' component is confined in semimajor axis (a) and eccentricity (e) compared to the more extended "hot" component; the cold component is confined to lower e and does not stretch all the way out to the 2:1 resonance but rather depletes quickly beyond a = 45 AU. For the cold main classical belt population we find a robust population estimate of N(Hg < 10) = 50 ± 5 × 103 and find that the hot component of the main classical belt represents ∼60% of the total population. The inner classical belt (sunward of the 3:2 mean-motion resonance) has a population of roughly 2000 trans-Neptunian objects with absolute magnitudes Hg < 10, and may not share the inclination distribution of the main classical belt. We also find that the plutino population lacks a cold low-inclination component, and so, the population is somewhat larger than recent estimates; our analysis shows a plutino population of N(Hg < 10)∼ 25+25−12 × 103compared to our estimate of the size of main classical Kuiper Belt population of N(Hg < 10) ∼ (126+50−46) × 103.