Cometary spectroscopy

LESIA, UMR8109 du CNRS, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France

e-mail: nicolas.biver@obspm.fr

Abstract

Cometary spectroscopy from the ultraviolet to the radio wavelength domain provides us with insights on the composition of the gases that are released by the cometary nuclei. While infrared to millimeter spectroscopy give access to the parent molecules that are released directly from the nucleus, visible spectroscopy enables observation of daughter species. Those “radicals” observable in the visible domain have more complex spectroscopic band-like structures and are mainly CN, C₂, C₃, NH₂. Their spectroscopic signatures are easily accessible to amateur astronomers class equipment. Provided that carefully calibrated data are acquired, some simple calculation can readily be done to convert the line intensities into comet molecular outgassing rates and thus provide interesting physical data on comets. In addition to broadband dust measurements, the interested amateur can produce valuable scientific data on comets that will always be welcome from the professional community and certainly useful as the monitoring of comets activity is always essential.