Publication Date:
2016-12-29
Description:
Comet 67P/Churyumov-Gerasimenko (67P) was imaged with the 2 m telescope at Mt. Wendelstein Observatory in the Alps. Coma and tail monitoring was performed during 51 nights between 2015 August 22 and 2016 May 9. The images through r and i Sloan Digital Sky Survey (SDSS) filters show the dust distribution around the comet, while images in the SDSS g filter also indicate the presence of coma gas in early 2015 September. The dust colour of 67P implies intrinsic reddening of 9 per cent/100 nm. After maximum, shortly after perihelion passage, the dust activity decreased with a heliocentric exponent of 4.1–4.2 from late 2015 September until 2016 May. The opposition surge during early 2016 can be explained by a linear light scattering phase function (β ~ 0.04) or an asteroid-like HG-type phase function ( G ~ 0.15). The radial brightness profile indicates a ‘quasi-steady-state’ dust coma from late September to the end of 2015. Dust fragmentation during about a month after perihelion may be responsible for radial coma profiles with slopes below unity, while dust accumulation due to very slow dust expansion velocity may result in steeper than unity profiles during 2016. Three fan-shape dust structures are characterized in the coma of 67P. A short dust ejection event on 2015 August 22–23 has produced a dust arc-let and jet feature in the coma. In 2015 September, the appearance of cometary dust tail is dominated by the young dust produced around perihelion. The older dust dominates the tail appearance as of 2015 mid-November.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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