Galin Borisov, Stefano Bagnulo, Plamen Nikolov, Tanyu Bonev

Imaging polarimetry and spectropolarimetry of comet C/2013 R1 (Lovejoy)

Figure 5. Enhanced coma structure in IF684 (top panel) and colour map (bottom panel) compared with polarisation (overplayed contours).


We have obtained imaging polarimetry of the comet C/2013 R1 (Lovejoy) with 2-Channel-Focal-Reducer Rozhen instrument at 2m Ritchey–Chrétien–Coudé telescope of the Bulgarian National Astronomical Observatory Rozhen in two dust continuum filters covering wavelength intervals clear from molecular emissions and centred at 4430 Å in blue filter and at 6840 Å in red filter. In imaging mode we measured the degree of linear polarisation 17.0170.09% in the blue and 18.8170.02% in the red, which is in a very good agreement with measurements of other comets at the similar phase angle. We have also obtained polarisation maps in both filters. We found a strong correlation between the spatial distribution of the polarisation and the dust colour. Spectropolarimetry of the nucleus region shows an increase of the polarisation with wavelength, and a depolarisation in the spectral regions with gas emission lines, most noticeable in C2 emission band, which shows a polarisation of 6.071.1%.

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Last Revised: 2015 August 3rd