Gas and dust release rates and color of dust in comets P/Halley (1986 III), P/Giacobini-Zinner (1985 XIII), and P/Hartley-Good (1985 XVII)

Abstract

CN, C 2, and C 3 emission fluxes observed at wavelengths of 388, 516, and 405 nm in the spectra of the comae of comets P/Halley (1986 III), P/Giacobini-Zinner (1985 XIII), and P/Hartley-Good (1985 XVII) were analyzed within the framework of the Haser model (Haser, Bull. Acad. R. Belg., Classe de Sciences 43, 740, 1957). Column densities and production rates of these gaseous species are determined and compared with those from other observations. For pre-perihelion heliocentric distances it is found that production rates/expansion velocity ( Q ν ) for species vary proportional to r − n , where n is 3.7 ± 0.8, 1.7 ± 0.7, and 4.7 ± 1.4 for CN, C 2, and C 3, respectively. Continuum fluxes measured at wavelengths of 484.5 and 412.0 nm were analyzed, and dust release rates in the coma of these comets are determined. The dust release rates decrease with increase of heliocentric distance for comet Halley, and follow a r −3.0±0.7 power law. Color excesses of grains were determined in comets P/Halley (1986 III), P/Giacobini-Zinner (1985 XIII), and P/Hartley-Good (1985 XVII).