Mosaicked images and spectra of J=1 -> 0 HCN and HCO+ emission from comet Hale-Bopp (1995 O1)

Citation
Mch. Wright et al., Mosaicked images and spectra of J=1 -> 0 HCN and HCO+ emission from comet Hale-Bopp (1995 O1), ASTRONOM J, 116(6), 1998, pp. 3018-3028
Citations number
47
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMICAL JOURNAL
ISSN journal
00046256 → ACNP
Volume
116
Issue
6
Year of publication
1998
Pages
3018 - 3028
Database
ISI
SICI code
0004-6256(199812)116:6<3018:MIASOJ>2.0.ZU;2-#
Abstract
We used the BIMA array to map comet Hale-Bopp (1995 O1) in HCN and HCO+ emi ssion at 89 GHz with 10 " angular resolution. The mosaicked images with sev en pointing centers were combined with single-dish data to form completely sampled images of a region similar to 4' in diameter. The HCN image is roug hly compatible with a Haser model in which most of the HCN comes from the n ucleus. However, clear deviations from circular symmetry are present, and r oughly 20% of the HCN does not appear to come from the nuclear source. Freq uently, the HCN has an asymmetric, double-peaked profile. The double peak i s expected from the Haser model, and the asymmetry observed on April 3 coul d come from an increased gas production toward the Sun and facing the obser ver. The abundance of HCN relative to H2O is similar to 0.3%. The HCO+, in contrast, is smooth, almost completely resolved in the interferometer obser vations, and offset toward the ion tail by about 1'. This behavior is compa tible with expectations from a simple scaling of previous work.