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Star formation and the circumstellar matter of young stellar objects

Published online by Cambridge University Press:  04 August 2017

Frank H. Shu  and
Fred C. Adams
Frank H. Shu
Affiliation:
Astronomy Department, University of California, Berkeley CA 94720, USA
Fred C. Adams
Affiliation:
Astronomy Department, University of California, Berkeley CA 94720, USA

Abstract

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We propose that the formation of low mass stars in molecular clouds takes place in four stages. The first stage is the formation of slowly rotating cloud cores through the slow leakage of magnetic (and turbulent) support by ambipolar diffusion. These cores asymptotically approach quasistatic states resembling singular isothermal spheres, but such end states cannot actually be reached because they are unstable. The second phase begins when a condensing cloud core passes the brink of instability and collapses dynamically from “inside-out,” building up a central protostar and nebular disk. The emergent spectral energy distributions of theoretical models in the infall stage are in close agreement with those of recently found infrared sources with steep spectra. As the rotating protostar gains mass, deuterium will eventually ignite in the central regions and drive the star nearly completely convective if its mass is less than about 2 M ⊙. This initiates the next step of evolution - the bipolar outflow phase - in which a stellar wind pushes outward and breaks through the infalling envelope. The initial breakout is likely to occur along the rotational poles, leading to collimated jets and bipolar outflows. The intense stellar wind eventually widens to sweep out gas in nearly all 4π steradian, revealing the fourth stage - a T Tauri star with a surrounding remnant nebular disk. Radiation from a disk adds an infrared excess to the expected spectral energy distribution of the revealed source. The detailed shape of this infrared excess depends on whether the disk is largely passive and merely reprocesses stellar photons, or is relatively massive and actively accreting. Both extremes of spectral shapes are observed in T Tauri stars; the amount of circumstellar material in the form of disks around nearly formed stars may be related to the dual issues of the origins of binary-star and planetary systems.

Type
Bipolar Flows, Jets and Protostars
Information
Symposium - International Astronomical Union , Volume 122: Circumstellar Matter , 1987 , pp. 7 - 22
Copyright
Copyright © Reidel 1987 

References

Abt, H. 1983, Ann. Rev. Astr. Ap., 21, 343.CrossRefGoogle Scholar
Adams, F. C., and Shu, F. H. 1985, Ap. J., 296, 655.Google Scholar
Adams, F. C., and Shu, F. H. 1986, Ap. J., in press (AS).Google Scholar
Adams, F. C., Lada, C. J. and Shu, F. H. 1987, Ap. J., in press (ALS).Google Scholar
Appenzeller, I., and Tscharnuter, W. 1974, Astr. Ap., 30, 423.Google Scholar
Bally, J., and Lada, C. J. 1983, Ap. J., 265, 824.CrossRefGoogle Scholar
Beckwith, S., Zuckerman, B., Skrutskie, M. F., and Dyck, H. M. 1984, Ap. J., 287, 793.Google Scholar
Bertout, C., and Yorke, H. W. 1978, in Protostars and Planets, ed. Gehrels, T. (Tucson: University of Arizona Press), p. 648.Google Scholar
Bodenheimer, P., and Sweigart, A. 1968, Ap. J., 152, 515.Google Scholar
Bodenheimer, P. 1980, in IAU Symposium No. 93, Fundamental Problems in the Theory of Stellar Evolution, ed. Sugimoto, D., Lamb, D. Q., and Schramm, D. N. (Dordrecht: Reidel), p. 5.Google Scholar
Burton, W. B. 1976, Ann. Rev. Astr. Ap., 14, 275.Google Scholar
Calvet, N., Basri, G., and Kuhi, L. V. 1984, Ap. J., 277, 725.Google Scholar
Cassen, P., Shu, F. H., and Terebey, S. 1985, in Protostars and Planets II, ed. Black, D. C. and Matthews, M. S. (Tucson: University of Arizona Press), p. 448.Google Scholar
Chandrasekhar, S. 1939, An Introduction to Stellar Structure (The University of Chicago Press).Google Scholar
Chini, R. 1981, Astr. Ap., 99, 346.Google Scholar
Cohen, M. 1983, Ap. J. (Letters), 270, L69.Google Scholar
Cohen, M. 1984, Physics Reports, 116, no. 4, 173.Google Scholar
Cohen, M., and Kuhi, L. V. 1979, Ap. J. Suppl., 41, 743.Google Scholar
Cohen, M., Harvey, P. M., Schwartz, R. D., and Wilking, B. A. 1984, Ap. J., 278, 671.CrossRefGoogle Scholar
Cohen, M., and Schwartz, R. D. 1983, Ap. J., 265, 877.Google Scholar
Davidson, and Jaffe, D. T. 1984, Ap. J. (Letters), 277, L13.Google Scholar
Elmegreen, B.G. 1979, Ap. J., 232, 729.Google Scholar
Elmegreen, B.G. 1986, preprint.Google Scholar
Elsasser, H., and Staude, H. J. 1978, Astr. Ap., 70, L3.Google Scholar
Goodman, A. 1986, private communication.Google Scholar
Grasdalen, G. L., Strom, S. E., Strom, K. M., Capps, R. W., Thompson, D., and Castelaz, M. 1984, Ap. J. (Letters), L57.Google Scholar
Hayashi, C., Hoshi, R., and Sugimoto, D. 1962, Prog. Theor. Phys. Suppl. No. 22. CrossRefGoogle Scholar
Herbig, G. 1962, Adv. Astr. Ap. 1, 47.Google Scholar
Klein, R. I., Sandford, M. T., and Shu, F. H. 1986, in preparation.Google Scholar
Klein, R. I., Whitaker, R. W., and Sandford, M. T. 1985, in Protostars and Planets II, ed. Black, D. C. and Matthews, M. S. (Tucson: University of Arizona Press), p. 340.Google Scholar
Konigl, A. 1982, Ap. J., 261, 115.Google Scholar
Kuhi, L. V. 1964, Ap. J., 140, 409.CrossRefGoogle Scholar
Lada, C. J. 1985, Ann. Rev. Astr. Ap., 23, 267.Google Scholar
Lada, C. J., and Wilking, B. A. 1984, Ap. J., 287, 610.Google Scholar
Larson, R. B. 1969, M. N. R. A.S., 145, 271.Google Scholar
Larson, R. B. 1969, M. N. R. A. S., 145, 297.Google Scholar
Lizano, S., and Shu, F. H. 1986, in preparation.Google Scholar
Martin-Pintado, J., Wilson, T. L., Gardner, F. F., and Henkel, C. 1983, Astr. Ap., 117, 145.Google Scholar
Mercer-Smith, J. A., Cameron, A. G. W., and Epstein, R. I. 1984, Ap. J., 287, 445.Google Scholar
Mundt, R., and Fried, J. W. 1983, Ap. J. (Letters), 274, L83.Google Scholar
Mundt, R., Walter, F. M., Feigelson, E. D., Finkenzeller, U., Herbig, G. H., and Odell, A. P. 1983, Ap. J., 269, 229.Google Scholar
Myers, P. C., and Benson, P. J. 1983, Ap. J., 266, 309.Google Scholar
Myers, P. C. 1987, in Star Forming Regions, ed. Peimbert, M. and Jugaku, J. (Dordrecht: Reidel).Google Scholar
Nakano, T., and Umebayashi, T. 1980, Pub. Astr. Soc. Japan, 32, 613.Google Scholar
Nakano, T. 1981, Prog. Theor. Phys. Suppl. No. 70, 54.Google Scholar
Nelson, L. A., Rappaport, S. A., and Joss, P. C. 1986, Ap. J., in press.Google Scholar
Parker, E. N. 1979, Cosmical Magnetic Fields (Oxford University Press).Google Scholar
Sargent, A., and Beckwith, S. 1986, in preparation.Google Scholar
Scoville, N. Z. 1986, in Star Formation in Galaxies, ed. Neugebauer, G. and Scoville, N. Z., in press.Google Scholar
Shu, F. H. 1977, Ap. J., 214, 488.Google Scholar
Shu, F. H. 1985, in The Milky Way, ed. van Woerden, H., Burton, W. B., Allen, R. J. (Dordrecht: Reidel), p. 561.Google Scholar
Shu, F. H. 1986, in Star Formation in Galaxies, ed. Neugebauer, G. and Scoville, N. Z., in press.Google Scholar
Shu, F. H., and Terebey, S. 1984, in Cool Stars, Stellar Systems, and the Sun, ed. Baliunas, S. and Hartmann, L. (Berlin: Springer-Verlag), p. 78.Google Scholar
Shu, F. H., Lizano, S., and Adams, F. C. 1987, in Star Forming Regions, ed. Peimbert, M. and Jugaku, J. (Dordrecht: Reidel).Google Scholar
Solomon, P. M. and Sanders, D. B., in Protostars and Planets II, ed. Black, D. C. and Matthews, M. S. (Tucson: University of Arizona Press), p. 59.Google Scholar
Stahler, S. W. 1983, Ap. J., 274, 822.Google Scholar
Stahler, S. W., Shu, F. H., and Taam, R. E. 1980, Ap. J., 241, 637 (SST).Google Scholar
Stahler, S. W., Shu, F. H., and Taam, R. E. 1980, Ap. J., 242, 226.Google Scholar
Stahler, S. W., Shu, F. H., and Taam, R. E. 1981, Ap. J., 248, 727.Google Scholar
Terebey, S., Shu, F. H., and Cassen, P. 1984, Ap. J., 286, 529.Google Scholar
Vogel, S., and Kuhi, L. 1981, Ap. J., 245, 960.Google Scholar
Wadiak, E. J., Wilson, T. L., Rood, R. T., and Johnston, K. J. 1985, Ap. J. (Letters), 295, L43.Google Scholar
Walter, F. W. 1986, Pub. Astr. Soc. Pac., in preparation.Google Scholar
Walmsley, M. 1987, this volume.Google Scholar
Whitworth, A., and Summers, D. 1985, M. N. R. A. S., 214, 1.Google Scholar
Wilking, B. A., and Lada, C. J. 1983, Ap. J., 274, 698.Google Scholar
Winkler, K. H., and Newman, M. J. 1980, Ap. J., 236, 201.Google Scholar
Yorke, H. W., and Krugel, E. 1977, Astr. Ap., 54, 183.Google Scholar
Yorke, H. W., and Shustov, B. M. 1981, Astr. Ap., 98, 125.Google Scholar
Young, E. T., Lada, C. J., and Wilking, B. A. 1986, Ap. J. (Letters), in press.Google Scholar
Zeng, Q., Batrla, W., and Wilson, T. L. 1984, Astr. Ap., 141, 127.Google Scholar
Zuckerman, B., and Palmer, P. 1974, Ann. Rev. Astr. Ap., 12, 279.Google Scholar