Hostname: page-component-5c6d5d7d68-txr5j Total loading time: 0 Render date: 2024-09-01T11:08:53.720Z Has data issue: false hasContentIssue false

Molecular Cloud Cores and Protostars: Offsprings of Gravity and Cosmic Magnetism

Published online by Cambridge University Press:  19 July 2016

Telemachos Ch. Mouschovias*
Affiliation:
University of Illinois at Urbana-Champaign Departments of Physics and Astronomy 1011 West Springfield Avenue Urbana, IL 61801, U. S. A.

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The formation of cloud cores (or fragments) and their evolution into protostars are the inevitable outcome of the struggle between gravity and magnetic fields, with ambipolar diffusion as the agent employed to weaken gravity's fierce opponent. The very specific and crucial role of magnetic fields in star formation deduced from detailed quantitative calculations is summarized. Criteria for collapse against magnetic and thermal-pressure forces are given. Magnetic braking time scales for both aligned and perpendicular rotators, and ambipolar diffusion time scales in both quasistatically and dynamically contracting cores are presented, and their implications are discussed. The possible role of magnetic fields in the determination of the initial (stellar) mass function (IMF) is beginning to emerge. New calculations on the axisymmetric collapse of clouds due to ambipolar diffusion reveal that the relation Bcρc1/2 between the magnetic field strength and the gas density in typical cloud cores holds even in the presence of ambipolar diffusion up to densities ~ 109 cm−3. Small masses, high densities, and strong fields observed in H2O masers are consistent with theoretical calculations.

Type
6. Magnetic Fields in Molecular Clouds, Dark Globules and in the Pre-Stellar and Circumstellar Environment
Copyright
Copyright © Kluwer 1990 

References

Abt, H. A. 1983, Ann. Rev. Astr. Ap. , 21, 343.CrossRefGoogle Scholar
Blitz, L., and Shu, F. H. 1980, Ap. J. , 238, 148.CrossRefGoogle Scholar
Bregman, J. D., Troland, T. H., Forster, J. R., Schwarz, U. J., Goss, W. M., and Heiles, C. 1983, Astr. Ap. , 118, 157.Google Scholar
Elmegreen, B. G. 1979, Ap. J. , 232, 729.CrossRefGoogle Scholar
Fiedler, R. A., and Mouschovias, T. Ch. 1990, Ap. J., to be submitted. Google Scholar
Field, G. B. 1965, Ap. J. , 142, 531.CrossRefGoogle Scholar
Goldsmith, P. F., and Arquilla, R. 1985, in Protostars & Planets II , eds. Black, D. C., and Matthews, M. S. (Tucson: Univ. of Arizona Press), p. 137.Google Scholar
Heiles, C. 1987, in Physical Processes in Interstellar Clouds , eds. Morfill, G. E. and Scholer, M. (Dordrecht Reidel), p. 429.CrossRefGoogle Scholar
Jeans, J. H. 1928, Astronomy and Cosmogony (Cambridge: Cambridge Univ. Press).Google Scholar
Lizano, S., and Shu, F. H. 1987, in Physical Processes in Interstellar Clouds , eds. Morfill, G. E. and Scholer, M. (Dordrecht Reidel), p. 173.CrossRefGoogle Scholar
McDaniel, E. W., and Mason, E. A. 1973, in The Mobility and Diffusion of Ions in Gases (New York: Wiley).Google Scholar
Mestel, L., and Spitzer, L. Jr. 1956, M. N. R. A. S. , 116, 503.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1974, Ap. J. , 192, 37.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1975a, Astr. Ap. , 40, 191.Google Scholar
Mouschovias, T. Ch. 1975b, Ph.D. Thesis , Univ. of California at Berkeley.Google Scholar
Mouschovias, T. Ch. 1976a, Ap. J. , 206, 753.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1976b, Ap. J. , 207, 141.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1977, Ap. J. , 211, 147.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1978, in Protostars and Planets , ed. Gehrels, T. (Tucson: U. of Ariz. Press), p. 209.Google Scholar
Mouschovias, T. Ch. 1979a, Ap. J. , 228, 159.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1979b, Ap. J. , 228, 475.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1981, in Fundamental Problems in the Theory of Stellar Evolution , eds. Sugimoto, D., Lamb, D. Q., and Schramm, D. N. (Dordrecht Reidel), p. 27.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1983, in Solar and Stellar Magnetic Fields: Origins and Coronal Effects , ed. Stenflo, J. O. (Dordrecht Reidel), p. 479.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1985, Astr. Ap. , 142, 41.Google Scholar
Mouschovias, T. Ch. 1987a, in Physical Processes in Interstellar Clouds , eds. Morfill, G. E. and Scholer, M. (Dordrecht Reidel), p. 453.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1987b, in Physical Processes in Interstellar Clouds , eds. Morfill, G. E. and Scholer, M. (Dordrecht Reidel), p. 491.CrossRefGoogle Scholar
Mouschovias, T. Ch. 1989, in The Physics and Chemistry of Interstellar Molecular Clouds , eds. Winnewisser, G. and Armstrong, J. T. (Berlin: Springer-Verlag), p. 297.Google Scholar
Mouschovias, T. Ch., and Morton, S. A. 1985a, Ap. J. , 298, 190.CrossRefGoogle Scholar
Mouschovias, T. Ch., and Morton, S. A. 1985b, Ap. J. , 298, 205.CrossRefGoogle Scholar
Mouschovias, T. Ch., and Morton, S. A. 1990, Ap. J., to be submitted. Google Scholar
Mouschovias, T. Ch., Morton, S. A., and Ciolek, G. 1990, in preparation. Mouschovias, T. Ch., and Paleologou, E. V. 1979, Ap. J., 230, 204.Google Scholar
Mouschovias, T. Ch., Morton, S. A., and Ciolek, G. 1980, Ap. J. , 237, 877.CrossRefGoogle Scholar
Mouschovias, T. Ch., Morton, S. A., and Ciolek, G. 1986, Ap. J. , 308, 781.CrossRefGoogle Scholar
Mouschovias, T. Ch., Paleologou, E. V., and Fiedler, R. A. 1985, Ap. J. , 291, 772.CrossRefGoogle Scholar
Mouschovias, T. Ch., and Spitzer, L. Jr. 1976, Ap. J. , 210, 326.CrossRefGoogle Scholar
Mouschovias, T. Ch., Shu, F. H., and Woodward, P. R. 1974, Astr. Ap. , 33, 73.Google Scholar
Myers, P. C. 1985, in Protostars & Planets II , eds. Black, D. C., and Matthews, M. S. (Tucson: Univ. of Arizona Press), p. 81.Google Scholar
Nakano, T. 1979, Publ. Astr. Soc. Japan , 31, 697 Google Scholar
Nakano, T., and Umebayashi, T. 1986, M. N. R. A. S. , 218, 663.CrossRefGoogle Scholar
Paleologou, E. V., and Mouschovias, T. Ch. 1983, Ap. J. , 275, 838.CrossRefGoogle Scholar
Parker, E. N. 1966, Ap. J. , 145, 811.CrossRefGoogle Scholar
Pneuman, G. W., and Mitchell, T. P. 1965, Icarus , 4, 494.CrossRefGoogle Scholar
Schwarz, U. J., Troland, T. H., Albinson, J. S., Bregman, J. D., Goss, W. M., and Heiles, C. 1986, Ap. J. , 301, 320.CrossRefGoogle Scholar
Shu, F. H. 1974, Astr. Ap. , 33, 55.Google Scholar
Shu, F. H. 1983, Ap. J. , 273, 202.CrossRefGoogle Scholar
Shu, F. H., Adams, F. C., and Lizano, S. 1987, Ann. Rev. Astr. Ap. , 25, 23.CrossRefGoogle Scholar
Spitzer, L. Jr. 1962, Physics of Fully Ionized Gases , 2nd ed. (New York: Interscience).Google Scholar
Spitzer, L. Jr. 1963, in Origin of the Solar System , eds. Jastrow, R. and Cameron, A. G. W. (New York: Academic Press), p. 39.CrossRefGoogle Scholar
Spitzer, L. Jr. 1978, Physical Processes in the Interstellar Medium (New York: Wiley-Interscience).Google Scholar
Tomisaka, K., Ikeuchi, S., and Nakamura, T. 1988, Ap. J. , 335, 239.CrossRefGoogle Scholar
Wheeler, J. C., Sneden, C., and Truran, J. W. Jr. 1989, Ann. Rev. Astr. A p. , in press.Google Scholar