Dust and atomic hydrogen nearρ Ophiuchi |
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Authors: | P Mészáros |
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Institution: | (1) Instituto Argentino de Radioastronomía, Buenos Aires, Argentina;(2) Present address: Berkeley Astronomy Department, University of California, 94720 Berkeley, Calif, U.S.A. |
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Abstract: | We discuss the distribution of dust and atomic hydrogen in and around a small dark cloud near Ophiuchi. Although the obscuration reaches values as high as 8 magnitudes, the values ofN
H derived inside the cloud do not differ markedly from those found at nearby, less obscured points. At low values of the obscuration, dust and hydrogen isophotes show satisfactory agreement, i.e.,N
H increases withN
G. However, we find thatN
H starts decreasing for sufficiently large values ofN
G. In the entire range of optical extinctions investigated our observations are satisfied by an expression of the typeN
H=AN
G exp (-BN
G). Interpretation of this relationship suggests that an appreciable part of the hydrogen has been converted to molecular form inside the cloud. A tentative method for calculating the time elapsed since the conversion process began is proposed.Contribution No. 2 from the Argentine-Carnegie Radio Astronomy Station of the Instituto argentino de Radioastronomía and the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. |
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Keywords: | |
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