The FU orionis outburst as a thermal accretion event: Theoretical and observational implications

  • K. R. Bell
Part II: Disks—Theory
Part of the Lecture Notes in Physics book series (LNP, volume 465)


Detailed calculations of viscous accretion disks suggest that FU Ori outbursts signify the existence of protostellar disks transporting mass at a time-averaged rate of (1–10)×10−6 M/yr around some fraction (≈10%) of young stellar objects. Accretion through the inner parts of these disks is self regulated by the thermal ionization instability such that long periods (≈1000 yr) of low mass flux: (1–10)×10−8 M/yr, are punctuated by short periods (≈100 yr) of high mass flux: (1–10)×10−5 M⊙/yr. The unstable region of the disk extends only to ≈ 1/4 AU. Beyond this region matter is transported stably through the disk at the infall rate, M in .

In systems for which M *=1 M with inner disk edges of 3 R, the critical rate for outburst is 5×10−7 M/yr independent of the magnitude of the viscosity. The magnitude of the alpha parameter may be constrained by global timescale fitting to be 10−4, where hydrogen is neutral, and 10−3 where ionized. This low viscosity has implications for self gravity as a possible mass transport mechanism through much of the disk. Light curves of V1515 Cyg, FU Ori, and V1057 Cyg are reproduced, and model results are compared to observations.


Mass Flux Light Curve Accretion Disk Stellar Mass Ionization Front 
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  1. Adams, F.C. & Shu, F.H. 1986, ApJ, 308, 836CrossRefADSGoogle Scholar
  2. Beckwith, S.V.W., Sargent, A.I., Chini, R.S., & Güsten, R. 1990, AJ 99, 924CrossRefADSGoogle Scholar
  3. Bell, K.R. 1994, in The Nature and Evolutionary Status of the Herbig Ae/Be Stars ed. P.S. Thé, M.P. Pérez, & E.P.J. van den Heuvel (ASP Conf. Series 62), 215Google Scholar
  4. Bell, K.R. & Lin, D.N.C. 1994, ApJ, 427, 987 (BL94)CrossRefADSGoogle Scholar
  5. Bell, K.R., Lin, D.N.C., Hartmann, L.W., & Kenyon, S.J. 1995, ApJ, May 1 (BLHK95)Google Scholar
  6. Bertout, C., Basri, G., & Bouvier, J. 1988, ApJ, 330, 350CrossRefADSGoogle Scholar
  7. Hartigan, Edwards, & Ghandour 1995 ApJ, 452, 736CrossRefADSGoogle Scholar
  8. Hartmann, L. & Kenyon, S.J. 1987, ApJ, 312, 243CrossRefADSGoogle Scholar
  9. Herbig, G.H. 1977, ApJ, 217, 693CrossRefADSGoogle Scholar
  10. Herbig, G.H. 1989, in ESO Workshop on Low Mass Star Formation and Pre-Main Sequence Objects, ed. B. Reipurth (ESO: Garching), No. 33, p. 233Google Scholar
  11. Kenyon, S.J. & Hartmann, L.W. 1991, ApJ, 383, 664CrossRefADSGoogle Scholar
  12. Kenyon, S.J., Hartmann, L., & Hewett, R. 1988, ApJ, 325, 231CrossRefADSGoogle Scholar
  13. Kenyon, S.J., Hartmann, L.W., & Kolotilov, E.A. 1991, PASP, 103, 1069CrossRefADSGoogle Scholar
  14. Lynden-Bell, D. & Pringle, J.E. 1974, MNRAS, 168, 603ADSGoogle Scholar
  15. Różczka, M.N., Bodenheimer, P.H., & Bell, K.R. 1994, ApJ, 423, 736CrossRefADSGoogle Scholar
  16. Ruden, S.P., Papaloizou, J., & Lin, D.N.C. 1988, ApJ, 329, 739CrossRefADSGoogle Scholar
  17. Shakura, N.I. & Sunyaev, R.A. 1973, A&A, 24, 337ADSGoogle Scholar
  18. Shu, F.H., Tremaine, S., Adams, F.C., & Ruden, S.P. 1990 ApJ, 358, 495CrossRefADSGoogle Scholar
  19. Strom, S.E., Edwards, S., & Skrutskie, M.F. 1993, in Protostars and Planets III, eds. E.H. Levy & J. Lunine (Tucson: Univ. of Arizona Press)Google Scholar
  20. Toomre, A. 1964, ApJ, 139, 1217CrossRefADSGoogle Scholar

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© Springer-Verlag 1996

Authors and Affiliations

  • K. R. Bell
    • 1
  1. 1.Space Sciences DivisionNASA Ames Research Center, MS 245-3Moffett FieldUSA

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