Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 16, 2004 | Published
Journal Article Open

The composition of ices in comet C/1995 O1 (Hale-Bopp) from radio spectroscopy

Abstract

From radio spectroscopic observations of comets, more than 22 molecules, radicals and ions, plus several isotopologues, were detected, the majority of them being recently revealed in comets C/1996 B2 (Hyakutake) and C/1995 O1 (Hale-Bopp). Among them, 6 molecules were detected for the first time (Bockelée-Morvan et al. [CITE]) in the course of a spectral survey conducted at radio wavelengths in comet Hale-Bopp with the CSO, the IRAM 30-m telescope and Plateau de Bure interferometer. In addition, many species were searched for unsuccessfully, some of them with stringent upper limits. We present here a review of these observations and further analysis of their results. This include: (i) confirmed detection of acetaldehyde (CH_3CHO); (ii) limits on small molecules such as ketene (H_2CCO) or methanimine (CH_2NH); (iii) limits on the abundance ratios in homologous series such as HC_5N/HC_3N, ethanol/methanol, acetic acid/formic acid; (iv) searches for precursors of key cometary species such as atomic Na and HNC; (v) constraints on more exotic species ranging from water dimer (H_2O)_2 to glycine; (vi) detection of the H_2^(34)S isotopic species and independent observations of HDO and DCN; (vii) limits on several other deuterated species; (viii) limits on several radicals and ions and a tentative detection of the C_2H radical; (ix) the presence of unidentified lines. Typical abundance upper limits of 2–5 x 10^(-4) relative to water are achieved for many species. Better upper limits are obtained for some linear molecules with high dipole moments. But more complex molecules such as dimethyl ether or glycine are poorly constrained. These results should give important clues to the chemical composition of cometary ices, to the formation mechanisms of cometary material, and to the chemical processes which occur in the inner coma.

Additional Information

© 2004 ESO. Received: 14 November 2003. Accepted: 26 January 2004. We are grateful to all the persons who participated in these target-of-opportunity observations: R. Bachiller, D. J. Benford, J. K. Davies, E. Gérard, B. Germain, M. Houde, D. Mehringer, R. Moreno, G. Paubert, T. G. Phillips, H. Rauer, & J. E. Wink. We thank L. H. Coudert, J. Demaison, E. Herbst, I. Kleiner & G. Wlodarczak who contributed to this work by providing lists of molecular transitions. The JPL and Cologne databases were crucial for the preparation of the observations, quick-look reduction and final analysis. This research has been supported by the Centre national de la recherche scientifique, the Programme national de planétologie de l'Institut national des sciences de l'univers, and NSF grant AST 2209008 to the Caltech Submillimeter Observatory. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

Attached Files

Published - aa0688.pdf

Files

aa0688.pdf
Files (448.5 kB)
Name Size Download all
md5:5f755a4083286348d634cbfeb85c412b
448.5 kB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023