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Stellar to Substellar Model Atmospheres

Published online by Cambridge University Press:  23 April 2012

France Allard
Affiliation:
Centre de Recherche Astrophysique de Lyon, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d'Italie, F-69364 Lyon Cedex 07, France, email: france.allard@ens-lyon.fr
Derek Homeier
Affiliation:
Centre de Recherche Astrophysique de Lyon, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d'Italie, F-69364 Lyon Cedex 07, France, email: france.allard@ens-lyon.fr
Bernd Freytag
Affiliation:
Centre de Recherche Astrophysique de Lyon, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d'Italie, F-69364 Lyon Cedex 07, France, email: france.allard@ens-lyon.fr
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Abstract

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The spectral transition from Very Low Mass stars (VLMs) to brown dwarfs (BDs) and planetary mass objects (Planemos) requires model atmospheres that can treat line, molecule, and dust-cloud formation with completeness and accuracy. One of the essential problems is the determination of the surface velocity field throughout the main sequence down to the BD and planemo mass regimes. We present local 2D and 3D radiation hydrodynamic simulations using the CO5BOLD code with binned Phoenix gas opacities, forsterite dust formation (and opacities) and rotation. The resulting velocity field vs depth and Teff has been used in the general purpose model atmosphere code Phoenix, adapted in static 1D spherical symmetry for these cool atmospheres. The result is a better understanding of the spectral transition from the stellar to substellar regimes. However, problems remain in reproducing the colors of the dustiest brown dwarfs. The global properties of rotation can change the averaged spectral properties of these objects. Our project for the period 2011-2015 is therefore to develop scaled down global 3D simulations of convection, cloud formation and rotation thanks to funding by the Agence Nationale de la Recherche in France.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

References

Ackerman, A. S. & Marley, M. S. 2001, ApJ, 556, 872Google Scholar
Allard, F. 1990, Ph.D. thesis, PhD thesis. Ruprecht Karls Univ. Heidelberg, (1990)Google Scholar
Allard, F. & Hauschildt, P. H. 1995, ApJ, 445, 433Google Scholar
Allard, F., Hauschildt, P. H., Alexander, D. R., Tamanai, A., & Schweitzer, A. 2001, ApJ, 556, 357Google Scholar
Allard, F., Hauschildt, P. H., & Schwenke, D. 2000, ApJ, 540, 1005Google Scholar
Asplund, M., Grevesse, N., Sauval, A. J., & Scott, P. 2009, ARAA, 47, 481Google Scholar
Baraffe, I., Chabrier, G., Allard, F., & Hauschildt, P. H. 1997, A&A, 327, 1054Google Scholar
Baraffe, I., Chabrier, G., Allard, F., & Hauschildt, P. H. 1998, A&A, 337, 403Google Scholar
Baraffe, I., Chabrier, G., Barman, T. S., Allard, F., & Hauschildt, P. H. 2003, A&A, 402, 701Google Scholar
Barber, R. J., Tennyson, J., Harris, G. J., & Tolchenov, R. N. 2006, MNRAS, 368, 1087CrossRefGoogle Scholar
Caffau, E., Ludwig, H.-G., Steffen, M., Freytag, B., & Bonifacio, P. 2011, Solar Phys., 268, 255CrossRefGoogle Scholar
Casagrande, L., Flynn, C., & Bessell, M. 2008, MNRAS, 389, 585Google Scholar
Chabrier, G., Baraffe, I., Allard, F., & Hauschildt, P. 2000, ApJ, 542, 464Google Scholar
Freytag, B., Allard, F., Ludwig, H., Homeier, D., & Steffen, M. 2010, A&A, 513, A19Google Scholar
Golimowski, D. A. & collaborators, 2004, AJ, 127, 3516CrossRefGoogle Scholar
Grevesse, N., Noels, A., & Sauval, A. J. 1993, A&A, 271, 587Google Scholar
Hauschildt, P. H., Allard, F., & Baron, E. 1999a, ApJ, 512, 377Google Scholar
Hauschildt, P. H., Allard, F., Ferguson, J., Baron, E., & Alexander, D. R. 1999b, ApJ, 525, 871Google Scholar
Helling, C., Ackerman, A., Allard, F., Dehn, M., Hauschildt, P., Homeier, D., Lodders, K., Marley, M., Rietmeijer, F., Tsuji, T., & Woitke, P. 2008, MNRAS, 391, 1854CrossRefGoogle Scholar
Jørgensen, U. G., Jensen, P., Sørensen, G. O., & Aringer, B. 2001, A&A, 372, 249Google Scholar
Lodders, K. & Fegley, B. Jr. 2006, In Astrophysics Update 2, editor: Mason, J. W.Spinger Verlag, p1.Google Scholar
Ludwig, C. B. 1971, Applied Optics, 10, 1057CrossRefGoogle Scholar
Partridge, H. & Schwenke, D. W. 1997, Journal for Computational Physics, 106, 4618Google Scholar
Rossow, W. B. 1978, ICARUS, 36, 1CrossRefGoogle Scholar
Schryber, J. H., Miller, S., & Tennyson, J. 1995, JQSRT, 53, 373Google Scholar
Seelmann, A. M., Hauschildt, P. H., & Baron, E. 2010, A&A, 522, A102Google Scholar
Steffen, M. & Freytag, B. 2007, AN, 328, 1054Google Scholar
Tsuji, T., Ohnaka, K., & Aoki, W. 1996a, A&A, 305, L1Google Scholar
Tsuji, T., Ohnaka, K., Aoki, W., & Nakajima, T. 1996b, A&A, 308, L29Google Scholar