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Limits on the Magnetic Flux of a Pre-Main Sequence Star

Published online by Cambridge University Press:  12 April 2016

G. Basri  and
G.W. Marcy
G. Basri
Affiliation:
Astronomy Department, University of California, Berkeley
G.W. Marcy
Affiliation:
Dept. of Physics and Astronomy, San Francisco State University

Abstract

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We attempt to detect a magnetic field on the weak T Tauri star, TAP35, via the enhanced equivalent widths of Zeeman-broadened absorption lines. We synthesize 25 Fe I lines, having a range of Zeeman sensitivities, using an LTE Stokes line-transfer calculation. The oscillator strengths of all lines are empirically determined a priori using the same line-transfer code applied to the spectrum of the magnetically quiet star, τ Ceti. The Fe abundance of TAP35 was established by synthesizing lines that are insensitive to Zeeman splitting. We find that the equivalent widths, Weq, of Zeeman-sensitive lines in TAP35 are systematically enhanced relative to the Zeeman-insensitive lines, consistent with the presence of widespread, kilogauss fields. The excess Weq can be explained by a product of field strength and surface filling factor (Bf) of 1 kiloGauss. A strong upper limit can be placed on the product of those two quantities, Bf < 2 kG. This measurement bears on the physics of T Tauri coronae, chromospheres, dynamos, and accretion-disk boundary layers.

Type
Part IV Stellar activity
Information
International Astronomical Union Colloquium , Volume 130: The Sun and Cool Stars: activity, magnetism, dynamos , 1991 , pp. 401 - 406
Copyright
Copyright © Springer-Verlag 1991

References

Arribas, S., Crivellari, L.: 1989, Astron. Astrophys. 210, 211 Google Scholar
Basri, G.: 1990, in High Resolution Spectroscopy in Astrophysics, a special issue of Memorie S.A. Ital., ed. Pallavicini, R. Google Scholar
Basri, G., Marcy, G.W.: 1988, Astrophys. J. 330, 274 Google Scholar
Blackwell, D.E., Petford, A.D., Simmons, G.J.: 1982, Mon. Not. R. Astron. Soc. 210, 595 Google Scholar
Brown, D., Landstreet: 1981, Astrophys. J. 246, 899 CrossRefGoogle Scholar
Cram, L.: 1979, Astrophys. J. 234, 949 CrossRefGoogle Scholar
Calvet, N. et al.: 1984, Astrophys. J. 277, 725 Google Scholar
Cohen, M., Beiging, J.H.: 1986, Astron. J. 92, 1396 Google Scholar
Finkenzeller, U., Basri, G.: 1987, Astrophys. J. 318, 823 Google Scholar
Fuhr, J.R., Martin, G.A., Wiese, W.L.: 1988, J. Phys. and Chem. Ref. Data 17, No. 4 Google Scholar
Gray, D.F.: 1976, in The Observation and Analysis of Stellar Photospheres, Wiley Google Scholar
Hartmann, L., Hewitt, R., Stahler, S., Mathieu, R.D.: 1986, Astrophys. J. 309, 275 Google Scholar
Herbig, G.H.: 1970, Mem. Roy. Soc. Sci. Liege 19, 13 Google Scholar
Holweger, H.: 1967, Z. Astrophys. 65, 365 Google Scholar
Holweger, H., Müller, E.A.: 1974, Solar Phys 39, 19 CrossRefGoogle Scholar
Imhoff, C., Giampapa, M.: 1982, in Advances in Ultraviolet Astronomy: four Years of IUE Res., ed. Kondo, Y., Mead, J.M., Chapman, R.D. (NASA CP 2338), p. 456 Google Scholar
Johnstone, R.M., Penston, M.V.: 1986, Mon. Not. Roy. Ast. Soc. 219, 927 CrossRefGoogle Scholar
Johnstone, R.M., Penston, M.V.: 1987, Mon. Not. Roy. Ast. Soc. 227, 797 Google Scholar
Kurucz, R.L., Furelid, I., Brault, J., Testerman, L.: 1984, Solar Flux Atlas from 269 to 1300 nm, National Solar Observatory Atlas No. 1Google Scholar
Marcy, G.W., Basri, G.: 1989, Astrophys. J. 345, 480 CrossRefGoogle Scholar
Saar, S.: 1988, Astrophys. J. 324, 441 Google Scholar
Shu, F.: 1990, private communicationGoogle Scholar
Vrba, F.J., Rydgren, A.E., Chugainov, P.F., Shakhovskaya, N.I., Weaver, W.B.: 1989, Astron. J. 97, 483 Google Scholar
Walter, F.M.: 1987, Pub. Ast. Soc. Pacific 99, 31 CrossRefGoogle Scholar
Walter, F.M.: 1988, Astron. J. 96, 297 Google Scholar