High Angular Resolution Study of the Ion and Neutral Spectra as a Probe of the Magnetic Field Structure

  • Shih-Ping Lai
  • T. Velusamy
  • W. D. Langer


We present the observations and analysis of the spectral linewidths of neutral and ion species across the DR21(OH) core to investigate the cyclotron interaction as a probe of magnetic fields. It has been suggested that under average interstellar field strengths the cyclotron interaction between ions and magnetic fields is strong enough to narrow the linewidth and suppress the line wings in the ion spectra. We have obtained high spatial resolution spectral line images of H13CN and H13CO+ at 3 mm in DR21(OH) with the Millimeter Array of the Owens Valley Radio Observatory. Our results show that in the eastern parts of the DR21(OH) core the spectral linewidth of the ions is narrower than that of the neutrals. We use our results, along with the existing Zeeman and dust/CO polarization data on small scales, to derive the 3D magnetic field structure. We obtain a field strength of 0.44 ± 0.12 mG with inclination of 36° to the line of sight, directed toward the observer, and a position angle of −75° in the plane of the sky.


star formation magnetic fields 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Crutcher, R.M.: 1999, Api 520, 706.ADSGoogle Scholar
  2. Crutcher, R.M., Troland, T.H., Lazareff, B., Paubert, G. and Kazès, I.: 1999, ApJL 514, L121.ADSCrossRefGoogle Scholar
  3. Dotson, J.L., Davidson, J., Dowell, C.D., Schleuning, D.A. and Hildebrand, R.H.: 2000, ApJS 128, 335.ADSCrossRefGoogle Scholar
  4. Girart, J.M., Crutcher, R.M. and Rao, R.: 1999, ApJL 525, L109.ADSCrossRefGoogle Scholar
  5. Houde, M., Bastien, P., Peng, R., Phillips, T.G. and Yoshida, H.: 2000a, ApJ 536, 857.ADSCrossRefGoogle Scholar
  6. Houde, M., Peng, R., Phillips, T.G., Bastien, P. and Yoshida, H.: 2000b, Api 537, 245.ADSGoogle Scholar
  7. Houde, M., Phillips, T.G., Bastien, P., Peng, R. and Yoshida, H.: 2001, ApJ 547, 311.ADSCrossRefGoogle Scholar
  8. Houde, M., Phillips, T.G., Bastien, P., Peng, R. and Yoshida, H.: 2001, ApJ 547, 311.Google Scholar
  9. Houde, M. et al.: 2002, Api 569, 803.ADSGoogle Scholar
  10. Lai, S.-P., Crutcher, R.M., Girart, J.M. and Rao, R.: 2001, Api 561, 864.ADSGoogle Scholar
  11. Lai, S.-P., Crutcher, R.M., Girart, J.M. and Rao, R.: 2002, Api 566, 925.ADSGoogle Scholar
  12. Lai, S.-P., Crutcher, R.M. and Girart, J.M.: 2003a, Api in press.Google Scholar
  13. Lai, S.-P., Velusamy, T. and Langer, W.D.: 2003b, Api 596, L239.ADSGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2004

Authors and Affiliations

  • Shih-Ping Lai
    • 1
  • T. Velusamy
    • 1
  • W. D. Langer
    • 1
  1. 1.Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaUSA

Personalised recommendations