Long-Term Monitoring of Comet 103P/Hartley 2

TL;DR

This study provides a comprehensive long-term observational analysis of comet 103P/Hartley 2, revealing jet features, dust properties, and chemical composition changes over several months, enhancing understanding of cometary activity and morphology.

Contribution

First detailed long-term monitoring of comet 103P/Hartley 2's dust and gas activity, including jet features and compositional analysis, from multiple observatories over eight months.

Findings

Detection of sunward dust feature from September to December 2010.

Observation of two distinct sunward jet features in October and November.

Comet's chemical ratio suggests typical cometary chemistry.

Abstract

We reported the monitoring results on spectrophotometry, photometry and imaging of comet 103P/Hartley 2 obtained at Lulin (1m), Calar Alto (2.2m) and Beijing Astronomical (2.16m) Observatory from April to December 2010. We found that a dust feature at sunward direction was detected starting from the end of September until the beginning of December (our last observation from the Lulin and Calar Alto observatory). Two distinct sunward jet features in the processed images were observed on October 11 and after October 29 until November 2. In parallel, the CN images reveal two asymmetrical jet features which are nearly perpendicular to the Sun-nucleus direction and this asymmetrical features implies that the comet was in a nearly side-on view in late-October and early-November. Additional to the jet features, the average result of the C2-to-CN production rate ratio ranges from 0.7 to 1.5 which places 103P/Hartley 2 as being of typical cometary chemistry. We found that the $r_h$ dependence for the dust production rate, Afrho (5,000 km), is -3.75+-0.45 before perihelion and is -3.44 +-1.20 during post-perihelion period. We detected the higher dust reddening is around the optocenter and getting bluer outward along the sunward jet feature and concluded that the former one, higher dust reddening, could be associated with strong jet activity and the latter one, the lowering of the reddening, might imply the optical properties changed or could be associated with outburst. The average dust color did not appear to vary significantly as the comet passed through perihelion.