Hostname: page-component-78c5997874-mlc7c Total loading time: 0 Render date: 2024-11-03T03:41:27.108Z Has data issue: false hasContentIssue false
  • English
  • Français

The role of magnetic fields for planetary formation

Published online by Cambridge University Press:  01 November 2008

Anders Johansen
Anders Johansen*
Affiliation:
Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands email: [email protected]
Rights & Permissions [Opens in a new window]

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 role of magnetic fields for the formation of planets is reviewed. Protoplanetary disc turbulence driven by the magnetorotational instability has a huge influence on the early stages of planet formation. Small dust grains are transported both vertically and radially in the disc by turbulent diffusion, counteracting sedimentation to the mid-plane and transporting crystalline material from the hot inner disc to the outer parts. The conclusion from recent efforts to measure the turbulent diffusion coefficient of magnetorotational turbulence is that turbulent diffusion of small particles is much stronger than naively thought. Larger particles – pebbles, rocks and boulders – get trapped in long-lived high pressure regions that arise spontaneously at large scales in the turbulent flow. These gas high pressures, in geostrophic balance with a sub-Keplerian/super-Keplerian zonal flow envelope, are excited by radial fluctuations in the Maxwell stress. The coherence time of the Maxwell stress is only a few orbits, where as the correlation time of the pressure bumps is comparable to the turbulent mixing time-scale, many tens or orbits on scales much greater than one scale height. The particle overdensities contract under the combined gravity of all the particles and condense into gravitationally bound clusters of rocks and boulders. These planetesimals have masses comparable to the dwarf planet Ceres. I conclude with thoughts on future priorities in the field of planet formation in turbulent discs.

Keywords

Diffusion – instabilities – MHD – planetary systems: protoplanetary disks – solar system: formation – turbulence
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Symposium S259: Cosmic Magnetic Fields: From Planets, to Stars and Galaxies , November 2008 , pp. 249 - 258
Copyright
Copyright © International Astronomical Union 2009

References

Balbus, S. A. & Hawley, J. F. 1991, ApJ 376, 21CrossRefGoogle Scholar
Blum, J. & Wurm, G. 2008, ARA&A 46, 21Google Scholar
Brauer, F., Henning, T., & Dullemond, C. P. 2008, A&A 487, L1Google Scholar
Brandenburg, A., Nordlund, Å., Stein, R.F., & Torkelsson, U. 1995, ApJ 446, 741CrossRefGoogle Scholar
Carballido, A., Stone, J. M., & Pringle, J. E. 2005, MNRAS 358, 1055CrossRefGoogle Scholar
Carballido, A., Fromang, S., & Papaloizou, J. 2006, MNRAS 373, 1633CrossRefGoogle Scholar
Carballido, A., Stone, J. M., & Turner, N. J. 2008, MNRAS 386, 145CrossRefGoogle Scholar
Cuzzi, J. N., Dobrovolskis, A. R., & Champney, J. M. 1993, Icarus 106, 102CrossRefGoogle Scholar
Dubrulle, B., Morfill, G., & Sterzik, M. 1995, Icarus 114, 237Google Scholar
Dullemond, C. P., Apai, D., & Walch, S. 2006, ApJ 640, L67CrossRefGoogle Scholar
Fromang, S. & Nelson, R. P., 2005, MNRAS 364, L81CrossRefGoogle Scholar
Fromang, S. & Nelson, R. P. 2006, A&A 457, 343Google Scholar
Fromang, S. & Papaloizou, J. 2006, A&A 452, 751Google Scholar
Gail, H.-P. 2002, A&A 390, 253Google Scholar
Gammie, C. F. 1996, ApJ 457, 355CrossRefGoogle Scholar
Goldreich, P. & Ward, W. R., 1973, ApJ 183, 1051CrossRefGoogle Scholar
Goodman, J. & Pindor, B. 2000, Icarus 148, 537CrossRefGoogle Scholar
Haghighipour, N., & Boss, A. P., 2003, ApJ 598, 1301CrossRefGoogle Scholar
Hawley, J. F., Gammie, C. F., & Balbus, S. A. 1996, ApJ 464, 690CrossRefGoogle Scholar
Hodgson, L. S. & Brandenburg, A. 1998, A&A 330, 1169Google Scholar
Inaba, S. & Barge, P. 2006, ApJ 649, 415CrossRefGoogle Scholar
Johansen, A. & Klahr, H. 2005, ApJ 634, 1353Google Scholar
Johansen, A., Klahr, H., Henning, Th. 2006, ApJ 636, 1121CrossRefGoogle Scholar
Johansen, A., Klahr, H., & Mee, A. J. 2006c, MNRAS 370, L71CrossRefGoogle Scholar
Johansen, A., Oishi, J. S., Low, M.-M. M., Klahr, H., Henning, T., & Youdin, A. 2007, Nature 448, 1022CrossRefGoogle Scholar
Johansen, A. & Youdin, A. 2007, ApJ 662, 627CrossRefGoogle Scholar
Johansen, A., Youdin, A., & Klahr, H. 2009, ApJ, submittedGoogle Scholar
Klahr, H. H. & Lin, D. N. C., 2001, ApJ 554, 1095CrossRefGoogle Scholar
Kretke, K. A. & Lin, D. N. C. 2007, ApJ 664, L55CrossRefGoogle Scholar
Levy, E. H. & Sonett, C. P. 1978, in: Gehrels, T. (ed.), IAU Colloqium 52: Protostars and Planets (The University of Arizona Press), p. 516Google Scholar
Lubow, S. H., Papaloizou, J. C. B., & Pringle, J. E. 1994, MNRAS 267, 235Google Scholar
Lyra, W., Johansen, A., Klahr, H., & Piskunov, N. 2008, A&A 479, 883Google Scholar
Lyra, W., Johansen, A., Klahr, H., & Piskunov, N. 2008, A&A 491, L41Google Scholar
Safronov, V. S. 1969, Evoliutsiia doplanetnogo oblaka (Nakua)Google Scholar
Sano, T., Miyama, S. M., Umebayashi, T., & Nakano, T. 2000, ApJ 543, 486CrossRefGoogle Scholar
Sano, T., Inutsuka, S.-i., Turner, N. J., & Stone, J. M. 2004, ApJ 605, 321CrossRefGoogle Scholar
Turner, N. J., Willacy, K., Bryden, G., & Yorke, H. W. 2006, ApJ 639, 1218CrossRefGoogle Scholar
van Boekel, R., et al. 2004, Nature 432, 479CrossRefGoogle Scholar
Varnière, P. & Tagger, M. 2006, A&A 446, 13Google Scholar
Völk, H. J., Morfill, G. E., Roeser, S., & Jones, F. C. 1980, A&A 85, 316Google Scholar
Weidenschilling, S. J. 1977, MNRAS 180, 57CrossRefGoogle Scholar
Whipple, F. L. 1972, in: Elvius, A. (ed.), From Plasma to Planet (Wiley Interscience Division), p. 211Google Scholar
Wurm, G., Paraskov, G., & Krauss, O. 2005, Icarus 178, 253Google Scholar
Youdin, A. N. & Goodman, J. 2005, ApJ 620, 459CrossRefGoogle Scholar
Youdin, A. N. & Johansen, A. 2007, ApJ 662, 613CrossRefGoogle Scholar
Youdin, A. N. & Lithwick, Y. 2007, Icarus 192, 588Google Scholar