T. Pieniluoma

Asteroid taxonomic signatures from photometric phase curves

Abstract We explore the correlation between an asteroid’s taxonomy and photometric phase curve using the H , G 12 photometric phase function, with the shape of the phase function described by the single parameter G 12 . We explore the usability of G 12 in taxonomic classification for individual objects, asteroid families, and dynamical groups. We conclude that the mean values of G 12 for the considered taxonomic complexes are statistically different, and also discuss the overall shape of the G 12 distribution for each taxonomic complex. Based on the values of G 12 for about half a million asteroids, we compute the probabilities of C, S, and X complex membership for each asteroid. For an individual asteroid, these probabilities are rather evenly distributed over all of the complexes, thus preventing meaningful classification. We then present and discuss the G 12 distributions for asteroid families, and predict the taxonomic complex preponderance for asteroid families given the distribution of G 12 in each family. For certain asteroid families, the probabilistic prediction of taxonomic complex preponderance can clearly be made. In particular, the C complex preponderant families are the easiest to detect, the Dora and Themis families being prime examples of such families. We continue by presenting the G 12 -based distribution of taxonomic complexes throughout the main asteroid belt in the proper element phase space. The Nysa–Polana family shows two distinct regions in the proper element space with different G 12 values dominating in each region. We conclude that the G 12 -based probabilistic distribution of taxonomic complexes through the main belt agrees with the general view of C complex asteroid proportion increasing towards the outer belt. We conclude that the G 12 photometric parameter cannot be used in determining taxonomic complex for individual asteroids, but it can be utilized in the statistical treatment of asteroid families and different regions of the main asteroid belt.

Asteroid phase curves from Lowell observatory photometric database

We present results obtained from processing large photometric data base. We make use of low-precision (generally rounded to 0.1 mag) and low-accuracy (rms magnitude uncertainties of ±0.2 to 0.3 mag) data obtained from the Minor Planet Center and modified at Lowell Observatory. We explore first correlations between slope parameter(s) and albedo, and second distributions of slope parameter(s) in asteroid families and taxa.