HCO/sup +/emission in the galactic center region. I. observations

Journal Article · Wed Oct 01 04:00:00 EDT 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158325· OSTI ID:6918667

Fukui, Y; Kaifu, N; Morimoto, M; Miyaji, T

HCO/sup +/ emission (3.4 mm, J=1--0) in the galactic center region has been observed toward the dense molecular clouds near Sgr A and Sgr B2 at over 20 points. The profiles are asymmetric, and are very widely extended in velocity like the /sup 12/CO line in spite of the high excitation requirements of the HCO/sup +/ line. A position-velocity map along the galacitc plane including the galactic nucleus was obtained. Comparison with the HCN emission leads us to the conclusion that the number density ratio (HCO/sup +/)/(HCN) is higher by an order of magnitude in the diffuse region. This behavior is discussed in terms of the ion-molecule reaction scheme. A dip of 0 km s/sup -1/, which is probably due to self-absorption by foreground cold molecular gas, was found in the HCO/sup +/ profiles as well as in spectra of HCN. The abundance of HCO/sup +/ relative to H/sub 2/ in the cold cloud is estimated to be > or approx. =10/sup -9.5/, which is remarkable large for such a low density cloud.

• Research Organization: Department of Astronomy, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
• OSTI ID: 6918667
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 241:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

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640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
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EMISSION SPECTRA
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GALAXY NUCLEI
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HYDROGEN COMPOUNDS
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