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.
This is a preview of subscription content, access via your institution
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Shakura, N. I. & Sunyaev, R. A. Black holes in binary systems. Observational appearance. Astron. Astrophys. 24, 337–355 (1973)
Pringle, J. E. Accretion discs in astrophysics. Annu. Rev. Astron. Astrophys. 19, 137–162 (1981)
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)
Pelletier, G. & Pudritz, R. E. Hydromagnetic disk winds in young stellar objects and active galactic nuclei. Astrophys. J. 394, 117–138 (1992)
Ferreira, J. Magnetically-driven jets from Keplerian accretion discs. Astron. Astrophys. 319, 340–359 (1997)
Bridle, H. A. & Perley, A. R. Extragalactic radio jets. Annu. Rev. Astron. Astrophys. 22, 319–358 (1984)
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)
Hartmann, L. & Kenyon, S. J. The FU Orionis phenomenon. Annu. Rev. Astron. Astrophys. 34, 207–240 (1996)
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)
Hutawarakorn, B. & Cohen, R. J. OH maser disc and magnetic field structure. Mon. Not. R. Astron. Soc. 357, 338–344 (2005)
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)
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)
Malbet, F. et al. New insights on the AU-scale circumstellar structure of FU Orionis. Astron. Astrophys. 437, 627–636 (2005)
Donati, J.-F. ESPaDOnS: An Echelle SpectroPolarimetric Device for the Observation of Stars at CFHT. ASP Conf. Proc. 307, 41–50 (2003)
Reipurth, B. & Aspin, C. The FU Orionis binary system and the formation of close binaries. Astrophys. J. 608, L68–L68 (2004)
Wang, H., Apai, D., Henning, T. & Pascucci, I. FU Orionis: a binary star? Astrophys. J. 601, L83–L86 (2004)
Preston, G. A statistical investigation of the orientation of magnetic axes in the periodic magnetic variables. Astrophys. J. 150, 547–550 (1967)
Johns-Krull, C. M. & Gafford, A. D. New tests of magnetospheric accretion in T Tauri stars. Astrophys. J. 573, 685–698 (2002)
Herbig, G. H. Eruptive phenomena in early stellar evolution. Astrophys. J. 217, 693–715 (1977)
Herbig, G. H., Petrov, P. P. & Duemmler, P. High-resolution spectroscopy of FU Orionis stars. Astrophys. J. 595, 384–411 (2003)
Hartmann, L. & Calvet, N. Observational constraints on FU Ori winds. Astron. J. 109, 1846–1855 (1995)
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)
Ferreira, J. & Pelletier, G. Magnetized accretion-ejection structures III. Stellar and extragalactic jets as weakly dissipative disk outflows. Astron. Astrophys. 295, 807–832 (1995)
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)
von Rekowski, B., Brandenburg, A., Dobler, W. & Shukurov, A. Structured outflow from a dynamo active accretion disc. Astron. Astrophys. 398, 825–844 (2003)
Dubrulle, B. et al. An hydrodynamic shear instability in stratified disks. Astron. Astrophys. 429, 1–13 (2005)
Balbus, S. A. & Hawley, J. F. A powerful local shear instability in weakly magnetised discs. Astrophys. J. 376, 214–233 (1991)
Keppens, R., Casse, F. & Goedbloed, J. P. Waves and instabilities in accretion disks: magnetohydrodynamic spectroscopic analysis. Astrophys. J. 569, L121–L126 (2002)
Horne, K. An optimal extraction algorithm for CCD spectroscopy. Publ. Astron. Soc. Pacif. 98, 609–617 (1986)
Kurucz, R. L. Atlas 9 Stellar Atmospheres and Programs [CD set] (Smithsonian Astrophysical Observatory, Cambridge, USA, 1993)
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.
Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.
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)
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)
Text to accompany the Supplementary Figures. (DOC 21 kb)
About this article
Cite this article
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). https://doi.org/10.1038/nature04253
This article is cited by
General Relativity and Gravitation (2018)
Astrophysics and Space Science (2018)
Space Science Reviews (2015)
Astrophysics and Space Science (2014)