Molecular ions in comet tails

Abstract

view Abstract Citations (45) References (75) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Molecular ions in comet tails. Wyckoff, S. ; Wehinger, P. A. Abstract The paper presents absolute emission-band intensities of the molecular ions CH(+), CO(+), N2(+), and H2O(+), which were measured using tail spectra of comets Kohoutek (1973f) and Bradfield (1974b). All the spectrograms were obtained with the spectrograph slit parallel to the tail axis of the comet; the observed band intensities and luminosities refer only to emitting ions within a projected radial distance of about 10,000 km centered on the coma. Photoionization and photodissociation rates are computed for the presumed parent molecules (CH, CO, N2, H2O), and emission-rate g-factors for the observed bands are calculated for photoionization plus excitation as well as for resonance fluorescence. The column densities of all the ions in Kohoutek, and of H2O(+) in Bradfield, are estimated for a heliocentric distance of 0.5 AU. It is shown that resonance fluorescence is the dominant production mechanism at about 1 AU, and it is found that CO(+) is approximately 100 times more abundant than any of the other ions in Kohoutek. Possible places of origin and production mechanisms for the neutral parent molecules are briefly considered. Publication: The Astrophysical Journal Pub Date: March 1976 DOI: 10.1086/154209 Bibcode: 1976ApJ...204..604W Keywords: Comet Tails; Kohoutek Comet; Molecular Ions; Molecular Spectra; Photodissociation; Photoionization; Absorption Cross Sections; Abundance; Astronomical Spectroscopy; Gas Density; Photodecomposition; Spectral Energy Distribution; Spectrograms; Astrophysics full text sources ADS |