Abstract
Results of observations of the solar limb effect in the non-magnetic lines Fei 512.4, 543.4, and 709.0 nm are presented. The detailed form of the limb-effect curves depends on the line strength. The weakest line, 709.0, shows a relative blueshift with respect to heliocentric angle from disc center to μ = 0.8 (μ = cos(heliocentric angle)). With increasing line strength the relative blueshift disappears and the redshift increases monotonically from the disc center to the limb. The strongest line, 543.4, shows a nearly linear redshift with decreasing μ, indicating little influence from horizontal motions.
Small, but systematic differences are found for all three lines between the line-shift measurements along the north-south and east-west diameters. The latitudinal variation of the limb effect is largest for the lines formed lowest in the atmosphere. The observations of the strongest line suggest the existence of a poleward meridional flow of 20–25 m s−1. Based on the measurements of the weaker lines a latitude variation in the granulation is suggested. One explanation is that the size of the granulation is about 5% larger at high latitudes as compared to the equatorial region.
Similar content being viewed by others
References
Albregtsen, F. and Andersen, B. N.: 1985, Solar Phys. 95, 239.
Altrock, R. C., November, L. S., Simon, G. W., Milkey, R. W., and Worden, S.: 1975, Solar Phys. 43, 33.
Andersen, B. N.: 1984a, Institute of Theoretical Astrophysics, Report No. 61.
Andersen, B. N.: 1984b, Solar Phys. 94, 49 (Paper I).
Andersen, B. N.: 1985, Solar Phys. 107, 27.
Balthasar, H.: 1984, Solar Phys. 93, 219.
Beckers, J. M.: 1978, in G. Belevedere and L. Paterno (eds.), Workshop on Solar Rotation, Catania, p. 166.
Beckers, J. M. and Milkey, R.: 1975, Solar Phys. 43, 289.
Beckers, J. M. and Morrison, R. A.: 1970, Solar Phys. 14, 280.
Beckers, J. M. and Nelson, G. D.: 1978, Solar Phys. 58, 243.
Brandt, P. N. and Schröter, E. H.: 1982, Solar Phys. 79, 3.
Dravins, D.: 1982, Ann. Rev. Astron. Astrophys. 20, 61.
Dravins, D., Lindegren, L., and Nordlund, Å.: 1981, Astron. Astrophys. 96, 345.
Durrant, C. J., Mattig, W., Nesis, A., Reiss, G., and Schmidt, W.: 1979, Astron. Astrophys. 61, 251.
Duvall, T. L.: 1979, Solar Phys. 63, 3.
Gilman, P. A. and Foukal, P. V.: 1979, Astrophys. J. 229, 1179.
Glatzmaier, G. A. and Gilman, P. A.: 1982, Astrophys. J. 256, 316.
Howard, R.: 1979, Astrophys. J. 228, L45.
Howard, R. and Harvey, J.: 1970, Solar Phys. 12, 23.
Kaisig, M. and Durrant, C. J.: 1982, Astron. Astrophys. 116, 332.
Kaisig, M. and Schröter, E. H.: 1983, Astron. Astrophys. 117, 305.
Keil, S. L.: 1980, Astrophys. J. 237, 1024.
Kubičela, A. and Karabin, M.: 1977, Solar Phys. 52, 199.
Küveler, G.: 1983, Solar Phys. 88, 13.
LaBonte, B. J. and Howard, R.: 1982, Solar Phys. 80, 361.
Livingston, W.: 1982, Nature 297, 208.
Mattig, W.: 1983, Solar Phys. 87, 187.
Mattig, W., Mehltretter, J., and Nesis, A.: 1981, Astron. Astrophys. 96, 96.
Moore, C. E., Minnaert, M. G. J., and Houtgast, J.: 1966, NBS Monog., No. 145.
Muller, R. and Roudier, T.: 1984, in Proc. Fourth Meeting on Solar Physics, Noordwijkerhout, 1–3 October, 1984.
Nordlund, Å.: 1984, in S. Keil (ed.), Small-Scale Dynamical Processes in Quiet Stellar Atmosphere, Sunspot 25–29 July, 1983, p. 181.
Pérez Garde, M., Vázquez, M., Schwan, H., and Wöhl, H.: 1981, Astron. Astrophys. 93, 67.
Ribes, E., Mein, P., and Mageney, A.: 1985, Nature 318, 170.
Snodgrass, H. B.: 1984, Solar Phys. 94, 13.
Wittman, A.: 1978, in F. L. Deubner, C. J. Durrant, M. Stix, and E. H. Schröter (eds.), Small-Scale Motions in the Sun, Mitt. Kiepenheuer Inst., No. 179, p. 29.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Andersen, B.N. Solar limb effect and meridional flows. Sol Phys 114, 207–222 (1987). https://doi.org/10.1007/BF00167341
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00167341