Abstract
We discuss the distribution of dust and atomic hydrogen in and around a small dark cloud nearρ 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.
Similar content being viewed by others
References
Allen, C. W.: 1963,Astrophysical Quantities (2nd ed.), The Athlone Press, London, p. 252.
Bok, B. J.: 1956,Astrophys. J. 61, 309.
Bok, B. J., Lawrence, R. S., andMenon, T. K. 1955,Publ. Astron. Soc. Pacific 68, 249.
Christiansen, W. N. andHindman, J. V.: 1952,Australian J. Sci. Res. A5, 437.
Field, G. B., Rather, J. D. G., Aanestad, P. A., andOrszag, S. A. 1968,Astrophys. J. 151, 953.
Field, G. B., Sommerville, W. B., andDressler, K. 1966,Ann. Rev. Astron. Astrophys. 4, 207.
Garzoli, S. L. andVarsavsky, C. M. 1966,Astrophys. J. 145, 79.
Gould, R. J. andSalpeter, E. E. 1963,Astrophys. J. 138, 408.
Heeschen, D. S.: 1955,Astrophys. J. 121, 569.
Heiles, C. E.: 1968,Astrophys. J. 151, 919.
Khavtassi, D. Sh.: 1960,Atlas of Galactic Dark Nebulae, Tbilis.
Knapp, H. F. P., Van den Meijdenberg, C. J. N., Beenakker, J. J. M., andVan de Hulst, H. C.: 1966,Bull. Astron. Inst. Neth. 18, 256.
Lilley, A. E.: 1955,Astrophys. J. 121, 559.
McCrea, W. H. andMcNally, D. 1960,Monthly Notices Roy. Astron. Soc. 121, 238.
McGee, R. X., Murray, J. D., andMilton, J. A.: 1963,Australian J. Phys. 16, 136.
Ross, F. E. andCalvert, M. R.: 1934–1936,Atlas of the Northern Milky Way, chart #5.
Stecher, T. P. andWilliams, D. A. 1966,Astrophys. J. 146, 88.
Stecher, T. P. andWilliams, D. A. 1967,Astrophys. J. (Letters) 149, L29.
Van de Hulst, H. C., Muller, C. A., andOort, J. H.: 1954,Bull. Astron Inst. Neth. 12, No. 452, 117.
Varsavsky, C. M.: 1968,Astrophys. J. 153, 627.
Author information
Authors and Affiliations
Additional information
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.
Rights and permissions
About this article
Cite this article
Mészáros, P. Dust and atomic hydrogen nearρ Ophiuchi. Astrophys Space Sci 2, 510–519 (1968). https://doi.org/10.1007/BF02175926
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02175926