The cyanogen abundance of comets.
Abstract
Expressions are provided with which the column density of CN molecules can be derived from low-resolution absolute radiance measurements of the (0, 0) band of the violet CN system at 338.3 nm in cometary spectra. Calculations are performed to obtain, as a function of heliocentric distance and heliocentric radial velocity, a conversion factor between the measured radiance (in W/sq m per sr) of the 338.3-nm CN band and the deduced column density (in CN molecules per sq m). Results of such calculations are presented for hypothetical comets at heliocentric distances ranging from 0.2 to 5.0 AU and with heliocentric radial velocities of -50 to +50 km/s. It is concluded that the radiance of the violet CN (0, 0) band will pass through a deep minimum at periheliom due to the presence of strong absorption lines of CN in the Fraunhofer spectrum of the sun.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1977
- DOI:
- 10.1086/155711
- Bibcode:
- 1977ApJ...218..569T
- Keywords:
-
- Abundance;
- Comets;
- Cyanogen;
- Astronomical Spectroscopy;
- Chemical Composition;
- Luminous Intensity;
- Perihelions;
- Radiance;
- Astrophysics