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Direct detection of a magnetic field in the innermost regions of an accretion disk


Models1,2,3,4,5 predict that magnetic fields play a crucial role in the physics of astrophysical accretion disks and their associated winds and jets6,7. For example, the rotation of the disk twists around the rotation axis the initially vertical magnetic field, which responds by slowing down the plasma in the disk and by causing it to fall towards the central star. The magnetic energy flux produced in this process points away from the disk, pushing the surface plasma outwards, leading to a wind from the disk and sometimes a collimated jet. But these predictions have hitherto not been supported by observations. Here we report the direct detection of the magnetic field in the core of the protostellar accretion disk FU Orionis8. The surface field reaches strengths of about 1 kG close to the centre of the disk, and it includes a significant azimuthal component, in good agreement with recent models5. But we find that the field is very filamentary and slows down the disk plasma much more than models predict, which may explain why FU Ori fails to collimate its wind into a jet.

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Figure 1: Magnetic field detection in the protostellar accretion disk FU Ori.
Figure 2: Disk and wind contribution to the LSD profiles of FU Ori.
Figure 3: Modelling the LSD profiles of FU Ori.


  1. Shakura, N. I. & Sunyaev, R. A. Black holes in binary systems. Observational appearance. Astron. Astrophys. 24, 337–355 (1973)

    ADS  Google Scholar 

  2. Pringle, J. E. Accretion discs in astrophysics. Annu. Rev. Astron. Astrophys. 19, 137–162 (1981)

    Article  ADS  Google Scholar 

  3. Blandford, R. D. & Payne, D. G. Hydromagnetic flows from accretion discs and the production of radio jets. Mon. Not. R. Astron. Soc. 199, 883–903 (1982)

    Article  ADS  Google Scholar 

  4. Pelletier, G. & Pudritz, R. E. Hydromagnetic disk winds in young stellar objects and active galactic nuclei. Astrophys. J. 394, 117–138 (1992)

    Article  ADS  Google Scholar 

  5. Ferreira, J. Magnetically-driven jets from Keplerian accretion discs. Astron. Astrophys. 319, 340–359 (1997)

    ADS  CAS  Google Scholar 

  6. Bridle, H. A. & Perley, A. R. Extragalactic radio jets. Annu. Rev. Astron. Astrophys. 22, 319–358 (1984)

    Article  ADS  CAS  Google Scholar 

  7. Ray, T. P., Mundt, R., Dyson, J. E., Falle, S. & Raga, A. C. HST observations of jets from young stars. Astrophys. J. 468, L103–L106 (1996)

    Article  ADS  CAS  Google Scholar 

  8. Hartmann, L. & Kenyon, S. J. The FU Orionis phenomenon. Annu. Rev. Astron. Astrophys. 34, 207–240 (1996)

    Article  ADS  CAS  Google Scholar 

  9. Hutawarakorn, B. & Cohen, R. J. Magnetic structure in the bipolar outflow source G 35.2–0.74N: MERLIN spectral line results. Mon. Not. R. Astron. Soc. 303, 845–854 (1999)

    Article  ADS  CAS  Google Scholar 

  10. Hutawarakorn, B. & Cohen, R. J. OH maser disc and magnetic field structure. Mon. Not. R. Astron. Soc. 357, 338–344 (2005)

    Article  ADS  CAS  Google Scholar 

  11. Donati, J.-F., Semel, M., Carter, B. D., Rees, D. E. & Cameron, A. C. Spectropolarimetric observations of active stars. Mon. Not. R. Astron. Soc. 291, 658–682 (1997)

    Article  ADS  Google Scholar 

  12. Donati, J.-F. et al. Dynamo processes and activity cycles of AB Dor, LQ Hya and HR 1099. Mon. Not. R. Astron. Soc. 345, 1145–1186 (2003)

    Article  ADS  Google Scholar 

  13. Malbet, F. et al. New insights on the AU-scale circumstellar structure of FU Orionis. Astron. Astrophys. 437, 627–636 (2005)

    Article  ADS  CAS  Google Scholar 

  14. Donati, J.-F. ESPaDOnS: An Echelle SpectroPolarimetric Device for the Observation of Stars at CFHT. ASP Conf. Proc. 307, 41–50 (2003)

    ADS  Google Scholar 

  15. Reipurth, B. & Aspin, C. The FU Orionis binary system and the formation of close binaries. Astrophys. J. 608, L68–L68 (2004)

    Article  ADS  Google Scholar 

  16. Wang, H., Apai, D., Henning, T. & Pascucci, I. FU Orionis: a binary star? Astrophys. J. 601, L83–L86 (2004)

    Article  ADS  Google Scholar 

  17. Preston, G. A statistical investigation of the orientation of magnetic axes in the periodic magnetic variables. Astrophys. J. 150, 547–550 (1967)

    Article  ADS  Google Scholar 

  18. Johns-Krull, C. M. & Gafford, A. D. New tests of magnetospheric accretion in T Tauri stars. Astrophys. J. 573, 685–698 (2002)

    Article  ADS  Google Scholar 

  19. Herbig, G. H. Eruptive phenomena in early stellar evolution. Astrophys. J. 217, 693–715 (1977)

    Article  ADS  CAS  Google Scholar 

  20. Herbig, G. H., Petrov, P. P. & Duemmler, P. High-resolution spectroscopy of FU Orionis stars. Astrophys. J. 595, 384–411 (2003)

    Article  ADS  CAS  Google Scholar 

  21. Hartmann, L. & Calvet, N. Observational constraints on FU Ori winds. Astron. J. 109, 1846–1855 (1995)

    Article  ADS  CAS  Google Scholar 

  22. Kenyon, S. J., Hartmann, L. & Hewett, R. Accretion disk models for FU Orionis and V1057 Cygni: detailed comparisons between observations and theory. Astrophys. J. 325, 231–251 (1988)

    Article  ADS  CAS  Google Scholar 

  23. Ferreira, J. & Pelletier, G. Magnetized accretion-ejection structures III. Stellar and extragalactic jets as weakly dissipative disk outflows. Astron. Astrophys. 295, 807–832 (1995)

    ADS  Google Scholar 

  24. Brandenburg, A., Nordlund, A., Stein, R. F. & Torkelsson, U. Dynamo-generated turbulence and large-scale magnetic fields in a Keplerian shear flow. Astrophys. J. 446, 741–754 (1995)

    Article  ADS  Google Scholar 

  25. von Rekowski, B., Brandenburg, A., Dobler, W. & Shukurov, A. Structured outflow from a dynamo active accretion disc. Astron. Astrophys. 398, 825–844 (2003)

    Article  ADS  Google Scholar 

  26. Dubrulle, B. et al. An hydrodynamic shear instability in stratified disks. Astron. Astrophys. 429, 1–13 (2005)

    Article  ADS  Google Scholar 

  27. Balbus, S. A. & Hawley, J. F. A powerful local shear instability in weakly magnetised discs. Astrophys. J. 376, 214–233 (1991)

    Article  ADS  Google Scholar 

  28. Keppens, R., Casse, F. & Goedbloed, J. P. Waves and instabilities in accretion disks: magnetohydrodynamic spectroscopic analysis. Astrophys. J. 569, L121–L126 (2002)

    Article  ADS  Google Scholar 

  29. Horne, K. An optimal extraction algorithm for CCD spectroscopy. Publ. Astron. Soc. Pacif. 98, 609–617 (1986)

    Article  ADS  CAS  Google Scholar 

  30. Kurucz, R. L. Atlas 9 Stellar Atmospheres and Programs [CD set] (Smithsonian Astrophysical Observatory, Cambridge, USA, 1993)

    Google Scholar 

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We thank the CFHT staff for help during the engineering runs of ESPaDOnS. We are grateful to F. Rincon and A. C. Cameron for comments on earlier versions of the manuscript. This Letter is based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

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Correspondence to Jean-François Donati.

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Supplementary information

Supplementary Figure 1

LSD Stokes V profiles of FU Ori in the blue and red spectral regions, demonstrating that the disc regions producing the detected Zeeman signature are at the same temperature as those generating the bulk of optical lines. (PDF 14 kb)

Supplementary Figure 2

Portions of the ESPaDOnS spectra of FU Ori showing weak, relatively unblended, features, demonstrating that LSD captures well the average shape of weak spectral features. (PDF 25 kb)

Supplementary Figure Legends

Text to accompany the Supplementary Figures. (DOC 21 kb)

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Donati, JF., Paletou, F., Bouvier, J. et al. Direct detection of a magnetic field in the innermost regions of an accretion disk. Nature 438, 466–469 (2005).

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