Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-25T07:24:46.292Z Has data issue: false hasContentIssue false
  • English
  • Français

Measuring T Tauri star magnetic fields

Published online by Cambridge University Press:  01 November 2008

Christopher M. Johns–Krull
Christopher M. Johns–Krull*
Affiliation:
Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA 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.

Stellar magnetic fields including a strong dipole component are believed to play a critical role in the early evolution of newly formed stars and their circumstellar accretion disks. It is currently believed that the stellar magnetic field truncates the accretion disk several stellar radii above the star. This action forces accreting material to flow along the field lines and accrete onto the star preferentially at high stellar latitudes. It is also thought that the stellar rotation rate becomes locked to the Keplerian velocity near the radius where the disk is truncated. This paper reviews recent efforts to measure the magnetic field properties of low mass pre-main sequence stars, focussing on how the observations compare with the theoretical expectations. A picture is emerging indicating that quite strong fields do indeed cover the majority of the surface on these stars; however, the dipole component of the field appears to be alarmingly small. The current measurements also suggest that given their strong magnetic fields, T Tauri stars are somewhat faint in X-rays relative to what is expected from simple main sequence star scaling laws.

Keywords

Accretion – accretion disks – stars: formation – stars: magnetic fields – stars: pre-main-sequence
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. 345 - 356
Copyright
Copyright © International Astronomical Union 2009

References

Alencar, S. & Basri, G. 2000, AJ 119, 1881CrossRefGoogle Scholar
Bouvier, J., Alencar, S. H. P., Harries, T. J., Johns–Krull, C. M., & Romanova, M. M. 2007, Protostars and Planets V, 479Google Scholar
Brown, D. N. & Landstreet, J. D. 1981, ApJ 246, 899CrossRefGoogle Scholar
Camenzind, M. 1990, Rev. Mod. Ast. 3, 234CrossRefGoogle Scholar
Collier Cameron, A. & Campbell, C. G. 1993, A&A 274, 309Google Scholar
Daou, A. G., Johns–Krull, C. M., & Valenti, J. A. 2006, AJ 131, 520CrossRefGoogle Scholar
Donati, J.-F., Paletou, F., Bouvier, J., & Ferreira, J. 2005, Nature 438, 466CrossRefGoogle Scholar
Donati, J.-F., Semel, M., Carter, B. D., Rees, D. E., & Collier Cameron, A. 1997, MNRAS 291, 658CrossRefGoogle Scholar
Donati, J.-F., et al. 2007, MNRAS 380, 1297CrossRefGoogle Scholar
Donati, J.-F., et al. 2008, MNRAS 386, 1234CrossRefGoogle Scholar
Edwards, S., Hartigan, P., Ghandour, L., & Andrulis, C. 1994, AJ 108, 1056CrossRefGoogle Scholar
Feigelson, E. D., Gaffney, J. A., Garmire, G., Hillenbrand, L. A., & Townsley, L. 2003, ApJ 584, 911CrossRefGoogle Scholar
Gregory, S. G., Jardine, M., Simpson, I., & Donati, J.-F. 2006, MNRAS 371, 999CrossRefGoogle Scholar
Guenther, E. W. & Emerson, J. P. 1996, A&A 309, 777Google Scholar
Guenther, E. W., Lehmann, H., Emerson, J. P., & Staude, J. 1999, A&A 341, 768Google Scholar
Johns-Krull, C. M. 2007, ApJ 664, 975CrossRefGoogle Scholar
Johns-Krull, C. M. & Valenti, J. A. 1996, ApJ 459, L95CrossRefGoogle Scholar
Johns-Krull, C. M., Valenti, J. A., & Koresko, C. 1999b, ApJ 516, 900CrossRefGoogle Scholar
Johns-Krull, C. M., Valenti, J. A., Hatzes, A. P., & Kanaan, A. 1999a, ApJL 510, L41CrossRefGoogle Scholar
Johns-Krull, C. M., Valenti, J. A., & Saar, S. H. 2004, ApJ 617, 1204CrossRefGoogle Scholar
Johnstone, R. M. & Penston, M. V. 1986, MNRAS 219, 927CrossRefGoogle Scholar
Johnstone, R. M. & Penston, M. V. 1987, MNRAS 227, 797CrossRefGoogle Scholar
Königl, A. 1991, ApJL 370, L39CrossRefGoogle Scholar
Luhmann, J. G., Gosling, J. T., Hoeksema, J. T., & Zhao, X. 1998, JGR 103, 6585CrossRefGoogle Scholar
Mathys, G. 2004, The A-Star Puzzle: Proc. IAUS 224, 225Google Scholar
Muzerolle, J., Calvet, N., & Hartmann, L. 2001, ApJ 550, 944CrossRefGoogle Scholar
Pevtsov, A. A., et al. 2003, ApJ 598, 1387CrossRefGoogle Scholar
Rüedi, I., Solanki, S. K., & Livingston, W. 1995, A&A 302, 543Google Scholar
Saar, S. H. & Linsky, J. L. 1985, ApJL 299, L47CrossRefGoogle Scholar
Shu, F. H., Najita, J., Ostriker, E., Wilkin, F., Ruden, S., & Lizano, S. 1994, ApJ 429, 781CrossRefGoogle Scholar
Smirnov, D. A., Fabrika, S. N., Lamzin, S. A., & Valyavin, G. G. 2003, A&A 401, 1057Google Scholar
Smirnov, D. A., Lamzin, S. A., Fabrika, S. N., & Chuntonov, G. A. 2004, Astronomy Letters 30, 456CrossRefGoogle Scholar
Stassun, K. G., Mathieu, R. D., Mazeh, T., & Vrba, F. J. 1999, AJ 117, 2941CrossRefGoogle Scholar
Symington, N. H., Harries, T. J., Kurosawa, R., & Naylor, T. 2005, MNRAS 358, 977CrossRefGoogle Scholar
Valenti, J. A., Basri, G., & Johns, C. M. 1993, AJ 106, 2024CrossRefGoogle Scholar
Valenti, J. A. & Johns-Krull, C. M. 2004, Ap&SS 292, 619Google Scholar
Valenti, J. A., Marcy, G. W., & Basri, G. 1995, ApJ 439, 939CrossRefGoogle Scholar
Vogt, S. S. 1980, ApJ 240, 567CrossRefGoogle Scholar
Uchida, Y. & Shibata, K. 1984, PASJ 36, 105Google Scholar
Yang, H., Johns-Krull, C. M., & Valenti, J. A. 2005, ApJ 635, 466CrossRefGoogle Scholar
Yang, H., Johns-Krull, C. M., & Valenti, J. A. 2007, AJ 133, 73CrossRefGoogle Scholar
Yang, H., Johns-Krull, C. M., & Valenti, J. A. 2008, AJ 136, 2286CrossRefGoogle Scholar