Spectroscopic Observations of New Oort Cloud Comet 2006 VZ13 and Four Other Comets

TL;DR

This study presents spectroscopic data for several comets, including a newly identified Oort cloud comet 2006 VZ13, analyzing their molecular emissions, dust properties, and compositional classifications.

Contribution

It provides the first spectral analysis of comet 2006 VZ13, revealing its classification as a carbon-depleted comet and examining molecular production rates across multiple comets.

Findings

Comet 2006 VZ13 is a new Oort cloud comet with strong CN, C_2, and C_3 emissions.

Production rates of C_2 and C_3 correlate with CN among the comets.

Dust-to-gas ratio shows a trend with heliocentric distance, independent of comet class.

Abstract

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 August 2007. Comet 2006 VZ13 is a new Oort cloud comet and shows strong lines of CN (3880 angstroms), the Swan band sequence for C_2 (4740, 5160, and 5630 angstroms), C_3 (4056 angstroms), and other faint species. Lines are also identified in the spectra of the other comets. Flux measurements of the CN, C_2 (Delta v = +1,0), and C_3 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 C_2 and C_3 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.