Radio wavelength molecular observations of comets C/1999 T1 (McNaught-Hartley), C/2001 A2 (LINEAR), C/2000 WM1(LINEAR) and 153P/Ikeya-Zhang

• Published in: Astronomy and astrophysics (Berlin) 2006-04, Vol.449 (3), p.1255-1270
• Main Authors: Biver, N., Bockelée-Morvan, D., Crovisier, J., Lis, D. C., Moreno, R., Colom, P., Henry, F., Herpin, F., Paubert, G., Womack, M.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics; comets: general; Cosmology and Extra-Galactic Astrophysics; Earth, ocean, space; Exact sciences and technology; Physics; radio lines: solar system; Sciences of the Universe; submilimetre
• ISSN: 0004-6361; 1432-0746; 1432-0756
• DOI: 10.1051/0004-6361:20053849

We present a comparative study of the relative abundances of CO, CH3OH, H2CO, HCN, HNC, CS, H2S, CH3CN, SO and HNCO in comets C/1999 T1 (McNaught-Hartley), C/2001 A2 (LINEAR), C/2000 WM1 (LINEAR) and 153P/Ikeya-Zhang, four of the brightest comets seen in 2001–2002. This investigation is based on millimetre/submillimetre observations made with the IRAM 30-m, SEST, CSO and Kitt Peak 12-m telescopes. Although these four comets are expected to originate from the Oort cloud, they present significant differences in molecular abundances, especially as regards to the most volatile species: CO and H2S. In particular comet C/2000 WM1 looks quite depleted in these volatiles, suggesting it may have a different origin than the others. Heliocentric variations of molecular relative abundance in the coma are also investigated. Significant increases in the CS/HCN and HNC/HCN production rate ratios with decreasing heliocentric distances are observed.