ISSN:
1573-0794
Keywords:
Comet Hale–Bopp
;
ions
;
HCO+
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract On-the-Fly maps of emission from the HCO+ J = 3-2 transition at 267.6 GHz were obtained of C/1995 O1 (Hale-Bopp) on 1997 Mar 15.6 UT using the NRAO 12-m telescope with high spatial resolution. Unlike the relatively symmetric and centralized maps of the neutral species CO, HCN and H2CO, the spatial extent of HCO+ emission is very diffuse with a complex structure characterized by at least two physically different regions. The bulk of the HCO+ emission peaks in intensity ∼175,000 km anti-sunward from the nuclear position. This peak emission does not fall directly along the anti-sunward direction, but is rotated by ∼10 degrees toward the east from the anti-sunward direction. A substantial void, or decrease, of HCO+ emission is observed within ∼ 55,000 km of the nucleus. The HCO+ emission in this void is roughly half the intensity of the emission observed 100,000 km away. This decrease of HCO+ emission near the nucleus may indicate that production or excitation of HCO+ is inhibited, or perhaps that HCO+ is easily destroyed in the inner coma, especially within ∼50,000 km of the nucleus. This void roughly coincides with the approximate location and size of the so-called “diamagnetic cavity” in the coma and may mark a significant transition region in the inner coma of Hale-Bopp
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006289820359
