SDSS-based taxonomic classification and orbital distribution of main belt asteroids

Abstract

Aims. The present paper aims to derive a new classification scheme for SDSS MOC asteroid colors that is compatible with previous taxonomies based on spectroscopic data. The distribution of these can give important clues to the formation and evolution of this region of the Solar System, as well as to locate candidates with mineralogically interesting spectra for detailed observations. Methods. The methodology is based on the large database SDSS MOC4. Templates of the main taxonomic classes are derived and then used to classify the asteroid observations in the SDSS MOC4. The derived taxonomic scheme is compatible with the Bus taxonomy and is suitable to the peculiarities of the SDSS observations, in particular, the low spectral resolution. Results. Density maps of the seven classes defined by the method reproduce classical results for the background which is mainly dominated by the S p class in the inner belt and by the X p and the C p classes beyond 2.8 AU. It also shows new structures, such as the fact that the X p and C p seem evenly distributed in the inner belt while in the outer belt the S p class increase in density only at the location of asteroid families. Although their overall distribution is similar, the X p class seems less frequently associated with large families than do the C p class asteroids. Although only clustering around the Vesta family, the V p class asteroidsnappear scattered all around the main belt. Besides the lack satisfactory explanations of most of the highlighted features, they may provide strong constraints on the models of the formation and evolution of the Solar System.

Basalt or Not? Near-infrared Spectra, Surface Mineralogical Estimates, and Meteorite Analogs for 33 Vp-type Asteroids

“…The asteroid classification system of Carvano et al (2010) is based on SDSS broadband filter observations of a relatively large number of asteroids (63,468), but with that useful and large number of taxonomic classifications come some unique characteristics. SDSS primarily obtains photometric data of stars, galaxies, and quasars, but the data have also been applied to study asteroids (Adelman-McCarthy et al 2006).…”

“…First, the five SDSS colors (u′g′r′i′z′) are solar-corrected and used to create very low-resolution, five-element, visible wavelength spectra that are the primary criterion used to define the different asteroid taxonomic classes. Second, the median spectra that define a given taxonomic class (Figure 2 of Carvano et al 2010) have associated limits on color gradient (i.e., spectral slope) that define the range of acceptability of observations that fit a given taxonomic class (Figure 1 of Carvano et al 2010). The limits on color gradient are the largest for the V p class for the (i -r) and (z -i) color indices (Carvano et al 2010).…”

“…Second, the median spectra that define a given taxonomic class (Figure 2 of Carvano et al 2010) have associated limits on color gradient (i.e., spectral slope) that define the range of acceptability of observations that fit a given taxonomic class (Figure 1 of Carvano et al 2010). The limits on color gradient are the largest for the V p class for the (i -r) and (z -i) color indices (Carvano et al 2010). In addition, the ranges of color gradient for the different classes exhibit some overlap, and Figure 2 from Carvano et al (2010) shows that the V p class overlaps with the Q p class and slightly with the O p class for the (z -i) color index.…”

“…The present work builds upon, and expands, the nearinfrared (NIR: 0.7 to 2.5 μm) spectral and mineralogical characterization of the V p taxonomic class of asteroids (Carvano et al 2010), which began with the work of Hardersen et al (2014Hardersen et al ( , 2015. The primary goals of this research are to: (1) identify those inner-belt V p asteroids that have a significant likelihood of having a basaltic surface composition and deriving from (4) Vesta (as Vestoids), (2) better constrain the abundance and distribution of outer-belt basaltic asteroids, and (3) test the predictive ability of the V p taxonomic class to accurately identify basaltic asteroids.…”

“…The predictive test of the V p class is an important component of this work because this taxonomy uses an average five-color spectrum derived from Sloan Digital Sky Survey (SDSS) colors to define its asteroid taxonomic classes (Carvano et al 2010). The connection between asteroid taxonomic classes, the parameters that define those classes, and the geological nature of asteroids is not direct nor guaranteed.…”