Fine-scale structure in cometary dust tails II: Further evidence for a solar wind influence on cometary dust dynamics from the analysis of striae in comet C/2011 L4 Pan-STARRS

Striated features, or striae, form in cometary dust tails due to an as-yet not fully constrained process or processes. Using STEREO-B SECCHI HI-1 instrument data, we display the evolution of striae in the tail of C/2011 L4 Pan-STARRS over a period of 8 days. This includes a period of morphological changes on 2013 March 14-15, similar to the reorganisation of striae previously observed in the tail of C/2006 P1 McNaught. This reorganisation is again attributed to Lorentz forces caused by the comet's dust tail crossing the heliospheric current sheet. We further analyse the alignments of reorganised striae at both C/2006 P1 and C/2011 L4 and show these alignments have mixed compatibility with an additional solar wind influence. We also report the discovery of a bright neutral sodium tail at C/2011 L4.