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Infrared emission lines of Mg II in B stars

Published online by Cambridge University Press:  26 May 2016

T. A. Aaron Sigut  and
J. B. Lester
T. A. Aaron Sigut
Affiliation:
Department of Astronomy, University of Toronto 60 St. George Street, Toronto, Ontario Canada M5S 1A7
J. B. Lester
Affiliation:
Department of Astronomy, University of Toronto 60 St. George Street, Toronto, Ontario Canada M5S 1A7

Extract

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Recently, Chang et. al. (1992) and Carlsson, Rutten and Shchukina (1992) (CRS) demonstrated the non-LTE formation mechanism behind the 12 μm Mg I emission lines (6g–7h, 6h–7i) observed in the solar spectrum (Murcray et. al., 1981). CRS stress the generality of this mechanism showing that it is a natural consequence of the recombination flow from the large Mg II reservoir through the Rydberg levels of Mg I. We have noted the close parallel between Mg I in the solar atmosphere and Mg II in the atmospheres of B stars (where Mg III plays the role of the reservoir) and investigated the operation of this mechanism in high-ℓ infrared transitions of Mg II. We have employed a 58 level Mg II atom including all energy levels through n = 25 and a total of 491 linearized radiative transitions. The coupled equations of radiative transfer and statistical equilibrium were solved with the MULTI code in its local operator form (Carlsson, 1992).

Type
6. Be Stars: Circumstellar Environment
Information
Symposium - International Astronomical Union , Volume 162: Pulsation, Rotation and Mass Loss in Early-Type Stars , 1994 , pp. 414 - 415
Copyright
Copyright © Kluwer 1994 

References

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Carlsson, M.: 1992, ‘The MULTI non-LTE program’ in Giampapa, M. S. and Bookbinder, J. A., ed(s)., Cool Stars, Stellar Systems and the Sun , A.S.P. Conf. Ser. Vol. 26, 499 Google Scholar
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Murcray, F.J., Goldman, A., Murcray, F.H., Bradford, C.M., Murcray, D.G., Coffey, M.T., Mankin, W.G.: 1981, Ap. J.(Letters) 247, L97 Google Scholar