SDSS Observations of Kuiper Belt Objects: Colors and Variability

Eran O. Ofek

Published 2012-02-07Version 1

Colors of Trans Neptunian Objects (TNOs) are used to study the evolutionary processes of bodies in the outskirts of the Solar System, and to test theories regarding their origin. Here I describe a search for serendipitous Sloan Digital Sky Survey (SDSS) observations of known TNOs and Centaurs. I present a catalog of SDSS photometry, colors and astrometry of 388 measurements of 42 outer Solar-System objects. I find a weak evidence, at the ~2-sigma level (per trial), for a correlation between the g-r color and inclination of scattered disk objects and hot classical KBOs. I find a correlation between the g-r color and the angular momentum in the z direction of all the objects in this sample. Light curves as a function of phase angle are constructed for 13 objects. The steepness of the slopes of these light curves suggests that the coherent backscatter mechanism plays a major role in the reflectivity of outer Solar-System small objects at small phase angles. I find a weak evidence for an anti-correlation, significant at the 2-sigma confidence level (per trial), between the g-band phase angle slope parameter and the semi-major axis, as well as the aphelion distance, of these objects. I discuss the origin of this possible correlation and argue that if this correlation is real it probably indicates that "Sedna"-like objects have a different origin than other classes of TNOs. Finally, I identify several objects with large variability amplitudes (abridged).