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17 - Velocity fields in stellar photospheres

Published online by Cambridge University Press:  05 March 2015

David F. Gray
David F. Gray
Affiliation:
University of Western Ontario
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Summary

Motions of the photospheric gases introduce Doppler shifts that shape the profiles of most spectral lines. Doppler shifts arising from the rotation of the star are equally significant, and often dominate the shaping process. (We concentrate on rotation in the next chapter.) In a very general sense, the shape of the distribution of Doppler shifts will be the shape taken on by the spectral lines. Our job is to make this quantitative, to work backward from the line profiles and deduce the nature of the velocity fields. The first task is to separate rotational broadening from the photospheric-velocities broadening. For the photosphere, we would like to know the geometry of the motion, whether we are dealing with wave motion, convective motion, prominence-like geysers, or some other kinds of flow. Measurements of the characteristic sizes and any temperature heterogeneities would help us discern what physics we are dealing with and whether or not the dynamics affects the ionization equilibrium, the excitation, and the transfer of radiation.

For the Sun we have a wealth of information with considerable spatial resolution, and there the velocity fields are dominated by granulation (the top of the convection zone) with a smaller contribution from non-radial oscillations. Since we have no spatial resolution for most other stars, we are fundamentally handicapped in having to deal with disk-integrated line profiles.

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Chapter
Information
The Observation and Analysis of Stellar Photospheres , pp. 423 - 457
Publisher: Cambridge University Press
Print publication year: 2005

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References

Abt, H.A. 1958. Ap. J. 127, 658.CrossRef
Asplund, M., Å., Nordlund, R., Trampedach, & R.F., Stein 1999. Ast. Ap. Lett. 346, L17.
Asplund, M., Å., Nordlund, R., Trampedach, C. Allende, Prieto, & R.F., Stein 2000. Ast. Ap. 359, 729.
Beckers, J.M. 1981. The Sun as a Star, NASA SP-450, ed. S., Jordan. (Washington: CNRS/NASA), p. 11.Google Scholar
Brandt, P.N. & S.K., Solanki 1990. Ast. Ap. 231, 221.
Bray, R.J., R.E., Loughhead, & C. J., Durrant 1984. The Solar Granulation, 2nd edn. (Cambridge: Univ. Cambridge).Google Scholar
Bray, R.J., R.E., Loughhead, & E.J., Tappere 1976. Solar Phys. 49, 3.CrossRef
Cavallini, F., G., Ceppatelli, & A., Righini 1985a. Ast. Ap. 143, 116.
Cavallini, F., G., Ceppatelli, & A., Righini 1985b. Ast. Ap. 150, 256.
Cavallini, F., G., Ceppatelli, & A., Righini 1988. Ast. Ap. 205, 278.
Claret, A. 2000. Ast. Ap. 363, 1081.
de Loore, C. 1970. Ap. Space Sci. 6, 60.CrossRef
Dravins, D. 1982. Ann. Rev. Ast. Ap. 20, 61.CrossRef
Dravins, D. 1987. Ast. Ap. 172, 200 & 211.
Dravins, D. 1990. Ast. Ap. 228, 218.
Dravins, D. & Å., Nordlund 1990a. Ast. Ap. 228, 184.
Dravins, D. & Å., Nordlund 1990b. Ast. Ap. 228, 203.
Dravins, D., L., Lindegren, & Å., Nordlund 1981. Ast. Ap. 96, 345.
Durrant, C.J. 1979. Ast. Ap. 76, 208.
Fensl, R.M. 1995. Ast. Ap. Suppl. 112, 191.
Freytag, B. & M., Mizuno-Wiedner 2002. Modeling of Stellar Atmospheres, ed. N., Piskunov, IAU Symp. 210, W. W., Weiss, & D. F., Gray, poster paper C4.Google Scholar
Gadun, A.S., S.K., Solanki, & A., Johannesson 1999. Ast. Ap. 350, 1018.
Gray, D.F. 1973. Ap. J. 184, 461.CrossRef
Gray, D.F. 1975. Ap. J. 202, 148.CrossRef
Gray, D.F. 1977. Ap. J. 218, 530.CrossRef
Gray, D.F. 1978. Solar Phys. 59, 193.CrossRef
Gray, D.F. 1980. Ap. J. 235, 508.CrossRef
Gray, D.F. 1981. Ap. J. 251, 583.CrossRef
Gray, D.F. 1982. Ap. J. 255, 200.CrossRef
Gray, D.F. 1986. Pub. Ast. Soc. Pacific 98, 319.CrossRef
Gray, D.F. 1988. Lectures on Spectral-Line Analysis: F, G, and K Stars, (Arva, Ontario: The Publisher).Google Scholar
Gray, D.F. 1989. Pub. Ast. Soc. Pacific 101, 832.CrossRef
Gray, D.F. 2002. Modeling of Stellar Atmospheres, IAU Symp. 210, ed. N., Piskunov, W.W, Weiss, & D. F., Gray. (San Franciso: Ast. Soc. Pacific), p. 287.Google Scholar
Gray, D.F. & J.L., Linsky, eds. 1980. Stellar Turbulence, IAU. Coll. No. 51, ed. D.F., Gray & J.L., Linsky. (Heidelberg: Springer-Verlag).CrossRefGoogle Scholar
Gray, D.F. & C.G., Toner 1985. Pub. Ast. Soc. Pacific 97, 543.CrossRef
Gray, D.F. & C.G., Toner 1986. Pub. Ast. Soc. Pacific 98, 499.CrossRef
Gray, D.F., S.L., Baliunas, G.W., Lockwood, & B.A., Skiff 1996. Ap. J. 456, 365.CrossRef
Huang, S.-S. & O., Struve 1953. Ap. J. 118, 463.CrossRef
Huang, S.-S. & O., Struve 1960. Stellar Atmospheres, ed. J.L., Greenstein. (Chicago: Univ. Chicago), Chapter 8.Google Scholar
Ichimoto, K., E., Hiei, & Y., Nakagomi 1989. Pub. Ast. Soc. Japan 41, 333.
Keil, S.L., ed. 1984. Small Scale Dynamical Processes in Quiet Stellar Atmospheres. (Sacramento: Sacramento Peak Obs.).Google Scholar
Keil, S.L. & R.C., Canfield 1978. Ast. Ap. 70, 169.
Keil, S.L. & F.H., Yackovich 1981. Solar Phys. 69, 213.CrossRef
Kraft, R.P. 1969. Stellar Astronomy, ed. H.-Y., Chiu, R.L., Warasila, & J.L., Remo. (New York: Gordon and Breach), p. 317.Google Scholar
Livingston, W.C. 1982. Nature 297, 208.CrossRef
Madsen, S., D., Dravins, & L., Lindegren 2002. Ast. Ap. 381, 446.
Magnan, C. 1976. J. Quan. Spect. Rad. Trans. 16, 281.CrossRef
Manduca, A., R.A., Bell, & B., Gustafsson 1977. Ast. Ap. 61, 809.
McMath, R.R., O.C., Mohler, A.K., Pierce, & L., Goldberg 1956. Ap. J. 124, 1.CrossRef
Nesis, A., A., Hanslmeier, R., Hammer, R., Komm, W., Mattig, & J., Staiger 1992. Ast. Ap. 253, 561.
Nordlund, Å. & D., Dravins 1990. Ast. Ap. 228, 155.
Orosz, J.A. & P.H., Hauschildt 2000. Ast. Ap. 364, 265.
Parker, E.N. 1982a. Ap. J. 256, 292.CrossRef
Parker, E.N. 1982b. Ap. J. 256, 302.CrossRef
Piskunov, N., W.W., Weiss, & D.F., Gray, eds. 2003. Modelling of Stellar Atmospheres, I.A.U. Symp. 210. (San Francisco: Ast. Soc. Pacific).Google Scholar
Renzini, A., C., Cacciari, P., Ulmschneider, & F., Schmitz 1977. Ast. Ap. 61, 39.
Rosseland, S. 1928. Mon. Not. Roy. Ast. Soc. 89, 49.CrossRef
Rutten, R.J. & G., Severino, eds. 1989. Solar and Stellar Granulation, NATO ASI Series, Vol. 263. (Dordrecht: Kluwer)CrossRefGoogle Scholar
Schröter, E.H. 1957. Z. f. Ap. 41, 141.
Slettebak, A. 1956. Ap. J. 124, 173.CrossRef
Smith, M.A. & D. F., Gray 1976. Pub. Ast. Soc. Pacific 88, 809.CrossRef
Spruit, H.C., Å., Nordlund, & A. M., Title 1990. Ann. Rev. Ast. Ap. 28, 263.CrossRef
Stathopoulou, M. & C. E., Alissandrakis 1993. Ast. Ap. 274, 555.
Stein, R.F. & Å., Nordlund 1998. Ap. J. 499, 914.CrossRef
Stencel, R. E. 1977. Ap. J. 215, 176.CrossRef
Struve, O. & C. T., Elvey 1934. Ap. J. 79, 409.CrossRef
Takeda, Y. 1995. Pub. Ast. Soc. Japan 47, 337.
Thomas, R. N. 1960. Aerodynamic Phenomena in Stellar Atmospheres, IAU Symp. 12, Fourth Symposium on Cosmic Gas Dynamics, Nuovo Cimento Suppl. 22, Series 10, No. 1, p. 9.
Toner, C. G. & D. F., Gray 1988. Ap. J. 334, 1008.CrossRef
Voigt, H.H. 1956. Z.f. Ap. 40, 157.
Voigt, H.H. 1959. Z. f. Ap. 47, 144.
Worrall, G. & A. M., Wilson 1972. Nature 236, 15.CrossRef
Worrall, G. & A. M., Wilson 1973. Vistas in Astronomy, Vol. 15. (London: Pergamon), p. 39.Google Scholar

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