The Canada-France-Hawaii Telescope Legacy Survey, specifically the Very Wide segment of data, is used to search for possible main-belt comets. In the first data set, 952 separate objects with asteroidal orbits within the main-belt are examined using a three-level technique. First, the full-width-half-maximum of each object is compared to stars of similar magnitude, to look for evidence of a coma. Second, the brightness profiles of each object are compared with three stars of the same magnitude, which are nearby on the image to ensure any extended profile is not due to imaging variations. Finally, the star profiles are subtracted from the asteroid profile and the residuals are compared with the background using an unpaired Ttest. No objects in this survey show evidence of cometary activity. The second survey includes 11438 objects in the main-belt, which are examined visually. One object, an unknown comet, is found to show cometary activity. Its motion is consistent with being a main-belt asteroid, but the observed arc is too short for a definitive orbit calculation. No other body in this survey shows evidence of cometary activity. Upper limits of the number of weakly and strongly active main-belt comets are derived to be 630±77 and 87±28, respectively. These limits are consistent with those expected from asteroid collisions. In addition, data extracted from the Canada-France-Hawaii Telescope image archive of main-belt comet 176P/LINEAR is presented.
Spectral data are presented for comets 2006 VZ13 (LINEAR), 2006 K4 (NEAT), 2006 OF2 (Broughton), 2P/Encke and 93P/Lovas I, obtained with the Cerro Tololo Inter‐American Observatory 1.5‐m telescope in 2007 August. Comet 2006 VZ13 is a new Oort cloud comet and shows strong lines of CN (3880 Å), the Swan band sequence for C2 (4740, 5160 and 5630 Å), C3 (4056 Å) and other faint species. Lines are also identified in the spectra of the other comets. Flux measurements of the CN, C2(Δv=+1, 0) and C3 lines are recorded for each comet and production rates and ratios are derived. When considering the comets as a group, there is a correlation of C2 and C3 production with CN, but there is no conclusive evidence that the production rate ratios depend on heliocentric distance. The continuum is also measured, and the dust production and dust‐to‐gas ratios are calculated. There is a general trend, for the group of comets, between the dust‐to‐gas ratio and heliocentric distance, but it does not depend on dynamical age or class. Comet 2006 VZ13 is determined to be in the carbon‐depleted (or Tempel 1 type) class.
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