Spectrum of the Short-Period Comet 2P/Encke in the Apparition of 2003

Abstract

Spectra of comet 2P/Encke obtained on November 15 and 22, 2003, in wavelength ranges of λ = 410–580 and 560–720 nm with the Universal Astronomical Grating Spectrograph (UAGS) mounted at the 1-m Zeiss-1000 telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences is analyzed. The spectral resolution is 0.5 nm. In the cometary coma, the emission bands of C₂, CN, CH, and NH₂ molecules were detected. The normalized spectral gradient of the reflectivity is (11.95 ± 3.45) and (7.90 ± 2.81)% per 100 nm in wavelength bands of 450–567 and 565–676 nm, respectively. The values of the parameter Afρ are (77 ± 9), (81 ± 9), and (79 ± 9) cm for the BC, GC, and RC continuum filters, respectively, which is indicative of a very low dust content in comet Encke. With the Haser model, we determined the production rate of gas molecules at (1.12 × 10²⁵) and (3.82 × 10²⁴) mol/s for C₂ (Δν = 0) and NH₂ (0,10,0) molecules, respectively.