HCO+ Imaging of Comet Hale-Bopp (C/1995 O1)

The HCO+ J = 1-0 rotational transition at 89.189 GHz has been mapped in comet Hale-Bopp (C/1995 O1) over a total of 38 individual days spanning the period 1997 March 10-June 20 with the Five College Radio Astronomy Observatory 14 m antenna. HCO+ is detectable over an extended region of the comet, wi...

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Bibliographic Details
Published in:The Astrophysical journal 1998-04, Vol.497 (2 Pt 2), p.L117-L121
Main Authors: Lovell, Amy J, Schloerb, F. Peter, Dickens, James E, DeVries, Christopher H, Senay, Matthew C, Irvine, William M
Format: Article
Language:English
Subjects:
Astronomy - instrumentation
Astronomy - methods
Extraterrestrial Environment
Hydrocarbons - chemistry
Ions
Lunar And Planetary Science And Exploration
Meteoroids
Models, Theoretical
Solar System
Space life sciences
Spectrum Analysis
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Summary:The HCO+ J = 1-0 rotational transition at 89.189 GHz has been mapped in comet Hale-Bopp (C/1995 O1) over a total of 38 individual days spanning the period 1997 March 10-June 20 with the Five College Radio Astronomy Observatory 14 m antenna. HCO+ is detectable over an extended region of the comet, with the peak emission commonly located 50,000-100,000 km in the antisolar direction. Maps made throughout the apparition show significant variability in the structure of the HCO+ coma, sometimes on timescales of several hours. The HCO+ brightness is usually depressed at the nucleus position, and on some occasions, the emission is spread into a ring around the position of the nucleus. Individual spectra within the maps display broad (approximately 4 km s-1) lines redshifted by 1-2 km s-1 or more from the nominal velocity of the nucleus, with the redshift typically increasing in the antisolar direction. The spectra and maps may be generally explained by models in which the ions are accelerated tailward at a rate on the order of 10 cm s-2, provided that HCO+ is destroyed within 50,000-100,000 km of the nucleus.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1086/311288