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Diffusion Models for Magnetic Ap Stars

Published online by Cambridge University Press:  12 April 2016

J. Babel
J. Babel*
Affiliation:
Institut d’Astronomie de l’Université de Lausanne, CH-1290 Chavannesdes-Bois, Switzerland

Abstract

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Progress made in spectroscopy and in the diffusion theory permits now to make severe comparisons, based on line profiles, between theory and observation.

We first review transport processes which are present in the atmospheric layers of Ap stars and discuss their relative importance. We then show that mass loss could play a key role for the creation of abundance maps. A mass loss model is proposed for 53 Cam and is compared, by spectrum synthesis, with visible and IUE high resolutions observations. The model accounts well for the line profiles of several elements with an exception for Ti. Furthermore, the abundance stratification predicted by this model gives close agreement with the large variation of the abundances of Cr and Fe found between the visible and UV domains. The diffusion-mass loss model finally permits to give a simple interpretation of the peculiar Ca II K lines observed in many Ap SrCrEu stars and in particular in 53 Cam, β CrB and HD 191742.

Type
V. Theory of CP Star Photospheres
Information
International Astronomical Union Colloquium , Volume 138: Peculiar versus Normal Phenomena in A-Type and Related Stars , 1993 , pp. 458 - 472
Copyright
Copyright © Astronomical Society of the Pacific 1993

References

Abbott, D.C.:1979, in IAU Symp. 83, Mass loss and Evolution of O-type stars, ed. Conti, P.S. and deLoore, C., (Dordrecht: Reidel), p. 237 Google Scholar
Abbott, D.C.:1982, ApJ, 259, 282 Google Scholar
Babcock, H.W.:1958, ApJS, 3, 141 Google Scholar
Babel, J.:1992, A&A, 258, 449 Google Scholar
Babel, J., Lanz, T.:1992, A&A, in pressGoogle Scholar
Babel, J., Michaud, G.:1991a, ApJ, 366, 560 (BM91a)Google Scholar
Babel, J., Michaud, G.:1991b, A&A, 241, 493 (BM91b)Google Scholar
Babel, J., Michaud, G.:1991c, A&A, 248, 155 (BM91c)Google Scholar
Bohlender, D.A., Landstreet, J.D.:1990, ApJ, 358, L25 Google Scholar
Borsenberger, J., Michaud, G., Praderie, F.:1981, ApJ, 243, 533 Google Scholar
Bürgi, A., Geiss, J.:1986, Solar Phys., 103, 347 Google Scholar
Burgers, J.M.:1969, Flow equations for Composite gases, Academic, New York Google Scholar
Fox, P.A., Theobald, M.L., Sofia, S.:1991, ApJ, 383, 860 Google Scholar
Kurucz, R.L.:1979, ApJS, 40, 1 CrossRefGoogle Scholar
Landstreet, J.D.:1988, ApJ, 326, 967 Google Scholar
Landstreet, J.D.:1992, A&A Rev., 4, 35 Google Scholar
Linsky, J.L., Drake, S.A., Bastian, T.S.:1992, ApJ, 393, 341 Google Scholar
Mégessier, C.:1984, A&A, 138, 267 Google Scholar
Michaud, G., Babel, J.:1991, In Stellar atmospheres: beyond classical models, NATO Advance Workshop, Eds. Crivellari, et al., Kluwer, p. 375 CrossRefGoogle Scholar
Michaud, G., Dupuis, J., Fontaine, G., Montmerle, T.:1987, ApJ, 322, 302 Google Scholar
Michaud, G., Mégessier, C., Charland, Y.:1981, A&A, 103, 244 Google Scholar
Michaud, G., Tarasick, D., Charland, Y., Pelletier, C.:1983, ApJ, 269, 239 Google Scholar
Peterson, D.M., Theys, J.C.:1981, ApJ, 244, 947 Google Scholar
Shore, S.N., Brown, D.N., Sonneborn, G., Landstreet, J.D., Bohlender, D.A.:1990, ApJ, 348, 242 Google Scholar
Unno, W.:1956, PASJ, 8, 108 Google Scholar
Vauclair, S.:1975, A&A, 45, 233 Google Scholar
Vauclair, S., Dolez, N., Gough, D.O.:1991, A&A, 252, 618 Google Scholar
Vauclair, S., Hardrop, J., Peterson, D.M.:1979, ApJ, 227, 526 Google Scholar
Wolff, S.C.:1983, The A-type Stars: Problems and Perspectives, NASA SP-463 Google Scholar