Polarimetry of comets 67P/Churyumov-Gerasimenko, 74P/Smirnova-Chernykh, and 152P/Helin-Lawrence

TL;DR

This study presents polarimetric observations of three Jupiter family comets at large heliocentric distances, revealing their activity levels and dust properties through detailed measurements and mapping.

Contribution

It provides new polarimetric data for three comets at large distances, extending understanding of comet dust properties beyond close approaches.

Findings

74P and 152P show detectable activity at large distances.

Polarimetric and colour maps reveal no evidence of dust particle structures.

The data expand knowledge of cometary dust behavior far from the Sun.

Abstract

Aims. Polarimetric characteristics of comets at large heliocentric distances is a relatively unexplored area; we extend the idea by adding and analysing the data for three Jupiter family comets (JFCs). Methods. With the FORS2 instrument of the ESO VLT, we performed quasi-simultaneous photometry and polarimetry of three active JFCs 67P/Churyumov-Gerasimenko, 74P/Smirnova-Chernykh, and 152P/Helin-Lawrence. Results. We obtained in total 23 polarimetric measurements at different epochs, covering a phase-angle range ~1 -16 degrees and heliocentric distances from 3 to 4.6 au. From our observations we obtained both colour and polarimetric maps to look for structures in the comae and tails of the comets. Conclusions. 74P/Smirnova-Chernykh and 152P/Helin-Lawrence exhibit enough activity at large heliocentric distances to be detectable in polarimetric measurements. Polarimetric and colour maps indicate no evidence of dust particle