Spectrophotometric differences of gas-dust environment of selected Jupiter's family comets and long-period comets with retrograde motion

Abstract The physical parameters of selected comets of the Jupiter family (22P/Kopff, 81P/Wild 2, 103P/Hartley 2) and the long-period comets with retrograde motion C/2006 W3 (Christensen), C/2009 K5 (McNaught), C/2009 P1 (Garradd) were obtained on the basis of optical spectra with resolution ((λ/Δλ) = 1500 and (λ/Δλ) = 14000). The spectra of comets were obtained in 2009–2012 at the mountain observatory « Peak Теrskоl» (Russian Federation, North Caucasus) with the help of the reflecting telescope Zeiss-2000 ( D  = 2.0 m; F 2  = 16 m). Based on the Haser model some physical parameters of gas-and-dust coma of comets (energy fluxes, molecule number, gas productivity, relative dust productivity) were estimated. The physical parameters of the neutral gas and dusty atmospheres of comets indicate that, at equal heliocentric distances, the gas and dust productivity of the considered long-period comets is higher than the productivity of Jupiter-family comets. The average values for gas productivity for the considered LPC are Q CN  = 6.99 × 10 25  mol/s, Q C3  = 5.35 × 10 24  mol/s, Q C2  = 3.17 × 10 26  mol/s, Q NH2  = 4.64 × 10 26  mol/s. The average values for gas productivity for the considered Jupiter-family comets are Q CN  = 1.52 × 10 25  mol/s, Q C3  = 1.54 × 10 24  mol/s, Q C2  = 2.12 × 10 25  mol/s, Q NH2  = 1.75 × 10 25  mol/s. The average values for dust productivity for the considered long-period comets is lg Afρ  = 4.241; for the considered Jupiter-family comets is lg Afρ  = 2.922. This can be explained by age-old disintegration or differences in the origin of different types of comets. Relative dust productivity ( Afρ ) of long-period comets with the retrograde motion before the perihelion is higher (taking into account the heliocentric distance). The doublet Na (D 1  = 588.9 nm, D 2  = 589.6 nm) at the considerable heliocentric distance in the spectra of comets 22Р/Kopff ( r  = 1.8 AU), 103Р/Hartley 2 ( r  = 1.06 AU), C/2009 K5 (McNaught) ( r  = 1.5 AU) was identified. The detailed identification of emission spectral lines for comets 103P/Hartley 2 and C/2009 K5 (McNaught) was carried out. The spectra of Hartley 2 have a much smaller number of molecular emission lines.