Comet C/2002 T7 (LINEAR): Polarimetric and photometric studies

• Published in: Solar system research 2006-05, Vol.40 (3), p.230-238
• Main Authors: Rosenbush, V K, Velichko, F P, Kiselev, N N, Velichko, S F, Shakhovskoy, N M, Efimov, Yu S, Antonyuk, K A, Kolesnikov, S V, Shakhovskoy, D N
• Format: Article
• Language: English
• Subjects: Astronomy; Comets; Dust; Filters; Polarization; Telescopes
• ISSN: 0038-0946; 1608-3423
• DOI: 10.1134/S0038094606030075

We present the results of polarimetric and photometric observations of dynamically new comet C/2002 T7 (LINEAR) at phase angles from 6° to 26°. During the observations, the comet was at a distance of 2.7-1.3 AU from the Sun and 1.7-2.0 AU from the Earth. The aperture polarimetry was made with the 2.6-m Shain telescope and the 1.25-m AZT-11 telescope of the Crimean Astrophysical Observatory and with the 0.7-m telescope of the Astronomical Institute of the Kharkiv National University during the period from November 21, 2003, to February 21, 2004. The wideband UBVRI and WRC (λ7228/1142 Å) filters and the narrowband GC (λ5260/56 Å) filter were used. The photometric observations of the comet were carried out on February 21, 2004, with narrowband filters isolated the BC (λ4845/65 Å) and RC (λ6840/90 Å) continuum and the C^sub 2^ emission (λ5140/90 Å). The phase-angle dependence of linear polarization of the comet has been obtained, and its parameters, such as the minimal polarization P^sub min^ = -1.63%, the phase angle of the minimal polarization α^sub min^ = 10.6°, the inversion angle α^sub inv^ = 22.7°, and the slope of the phase curve at the inversion angle h = 0.24% per degree, were found. From the photometric observations, the following quantities have been obtained: the column density of molecules C^sub 2^ in the line of sight logN (C^sub 2^) = -9.15 mol/cm^sup 2^ and their production rate log Q (C^sub 2^) = 27.11 mol/s, the spectral gradient of reflectivity for the dust S'(BC, RC) [asymptotically =] 3%/1000 Å, and the dust production parameter Afρ equal to 371 and 273 cm for the blue and red continuum ranges, respectively. According to these results, the physical parameters of comet C/2002 T7 are close to the average characteristics of typical dusty comets.[PUBLICATION ABSTRACT]