The Distribution of Highly Red-sloped Asteroids in the Middle and Outer Main Belt

Abstract

Red (S > 10%/0.1 micron) spectral slopes are common among Centaurs and trans-Neptunian objects (TNOs) in the outer solar system. Interior to and co-orbital with Jupiter, the red (S approx. = 10%/0.1 micron) slopes of D-type main-belt and Jupiter Trojan asteroids are thought to reflect their hypothesized shared origin with TNOs beyond the orbit of Jupiter. In order to quantify the abundance of red-sloped asteroids within the main belt, we conducted a survey using the NASA Infrared Telescope Facility and the Lowell Discovery Telescope. We followed up on 32 candidate red objects identified via spectrophotometry from the Sloan Digital Sky Survey's Moving Object Catalog to confirm their steep spectral slopes and determine their taxonomic classifications. We find that our criteria for identifying candidate red objects from the Moving Object Catalog result in an approx. 50% confirmation rate for steeply red-sloped asteroids. We also compare our observations of main-belt asteroids to existing literature spectra of the Jupiter Trojans and steeply red-sloped main-belt asteroids. We show that some red-sloped asteroids have linearly increasing reflectance with increasing wavelength, while other red-sloped asteroids show a flattening in slope at longer near-infrared wavelengths, indicating a diversity among the population of spectrally red main-belt asteroids suggestive of a variety of origins among the population of steep-sloped asteroids.

23 pages, 8 figures, draft version accepted to PSJ

References in corpus (8)

• Solar System evolution from compositional mapping of the asteroid belt
• Asteroid Taxonomy from Cluster Analysis of Spectrometry and Albedo
• A hypothesis for the color bimodality of Jupiter Trojans
• The consequences of planetary migration on the minor bodies of the early Solar System
• The differing magnitude distributions of the two Jupiter Trojan color populations
• Twenty years of SpeX: Accuracy limits of spectral slope measurements in asteroid spectroscopy
• The infrared colors of the Sun
• Discovery of two TNO-like bodies in the asteroid belt

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