Polarimetric and spectroscopic observations of a dynamically new comet C/2012 J1 (Catalina)

Abstract

Abstract. We present the analysis of the polarimetric and spectral data obtained for the dynamically new comet C/2012 J1 (Catalina) when it was at a distance of 3.17 AU from the Sun. The observations were made at the prime focus of the 6-m BTA telescope using the SCORPIO-2 focal reducer. The map of the distribution of linear polarization in the cometary coma was constructed. The calculated value of linear polarization was on average about −2%. Spectral analysis of the cometary coma allowed us to detect the emission of the CN molecule in the (0-0) band. The gas production rate was derived using the Haser model and amounted to 3.7 × 10 23 molecules per second.

Spectra of comet C/2002 T7 (LINEAR)

“…Bonev et al [4] and Ivanova et al [9] obtained slightly lower than previous results, but significantly higher than our results: 15% and 17% per 1000 Å for the comets C/2000 WM1 (LINEAR) and C/2012 J1 (Catalina), respectively. Meanwhile, the reflectivity gradient for the comet C/2004 Q2 (Machholz) varied from 0.6% to 9% per 1000 Å [14].…”

Comet 2P/Encke in apparition of 2017: II. Polarization and color

“…The correction for the zero point of instrumental position angle ΔPA was found from observations of standard stars with large interstellar polarization (Hsu and Breger, 1982). The image processing, reduction, errors estimation, and the method of calculation of polarization parameters with SCORPIO-2 are described in more details by Afanasiev and Amirkhanyan (2012), Afanasiev et al (2014), Ivanova et al (2015, 2017a, 2017b), and Rosenbush et al (2017.…”

Retrieval of microphysical characteristics of particles in atmospheres of distant comets from ground-based polarimetry

“…The first results of such observations have been published in Refs. [8,9]. In particular, they show a deeper branch of negative polarization at small phase angles in comparison with that observed for comets close to the Sun.…”

“…A detailed description of the procedure used to process polarimetric images is given in Refs. [9,22]. Table 1 provides the following information: the date of an observation (the mid-cycle time); the respective heliocentric, r, and geocentric, Δ, distances; the phase angle α; the spectral filter and its effective wavelength λ eff ; the total exposure time T exp ; the degree of linear polarization P; and the name of the comet.…”