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Measurements of Horizontal Flows in 1.6 μm Granulation

Published online by Cambridge University Press:  03 August 2017

Tron A. Darvann
Tron A. Darvann*
Affiliation:
Institute of Theoretical Astrophysics, University of Oslo, P. O. Box 1029 Blindern, N-0315 Oslo, Norway National Solar Observatory,* Sunspot, NM 88349, U.S.A.

Abstract

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We report on a first analysis of the horizontal motions in a 45 minute (32 × 22 arcsec2 field of view) granulation time series (movie presented at the present IAU Symposium) obtained at 1.6 μm with the Vacuum Tower Telescope (VTT) of the National Solar Observatory at Sacramento Peak (NSO/SP). High signal/noise flow maps are obtained by use of the local cross correlation technique (November 1986) which incorporates efficient attenuation of seeing and 5-min oscillations. The flow pattern, showing a (≈ 30 arcsec diameter) supergranule with (≈ 8-15 arcsec) mesogranules superposed, is long lived compared to the 45 min of observations. The computed flows (velocity, divergence, vorticity) resemble the ones obtained at visible wavelengths (e.g., by Brandt et al. 1991, November 1989, November and Simon 1988, Simon et al. 1988). The high quality of the the flow maps (due to a large number of selected images (1500), and (supposedly) smaller 5-min oscillations and better seeing conditions at 1.6 μm) allows us to study time evolution (resolution ≈ 15 min) of the details of the flow (spatial resolution ≈ 3 arcsec). An interesting new finding is the short lifetime (< 45 min) of vorticity as opposed to the long lived (≫ 45 min) divergence of the flow. Our study demonstrates the possibility of using the 1.6 μm window to the opacity minimum region to study the horizontal flows at these deep layers of the photosphere.

Keywords

infrared: starsSun: granulationSun: photosphere
Type
Part 3: Infrared Perspectives on Atmospheric Dynamics
Information
Symposium - International Astronomical Union , Volume 154: Infrared Solar Physics , 1994 , pp. 259 - 264
Copyright
Copyright © Kluwer 1994 

References

Brandt, P.N., Ferguson, S., Scharmer, G.B., Shine, R.A., Tarbell, T.D., Title, A.M., Topka, K.: 1991, Astron. Astrophys. 241, 219.Google Scholar
Darvann, T.A.: 1991, Cand. Scient. , Google Scholar
Keil, S.L.: 1980, Ap. J. 237, 1024.CrossRefGoogle Scholar
Keil, S.L., Kuhn, J.R., Lin, H., Reardon, K.: 1993, these proceedings.Google Scholar
Koutchmy, S.: 1993, these proceedings.Google Scholar
Koutchmy, O., Koutchmy, S.: 1989, in von der Lühe, O. (ed.), High Resolution Solar Observations, National Solar Observatory, p. 217.Google Scholar
Muller, R., Roudier, Th., Vigneau, J., Frank, Z., Shine, R., Tarbell, T., Title, A., Simon, G.W.: 1990, in Dezso, L. (ed.), The Dynamic Sun, Debrecen, p. 44.Google Scholar
November, L.J.: 1986, Appl. Opt. 25, 391.CrossRefGoogle Scholar
November, L.J.: 1989, Ap. J. 344, 494.CrossRefGoogle Scholar
November, L.J., Simon, G.W.: 1988, Ap. J. 333, 427.CrossRefGoogle Scholar
Simon, G.W., Title, A.M., Topka, K.P., Tarbell, T.D., Shine, R.A., Ferguson, S.H., Zirin, H., and The SOUP Team: 1988, Ap. J. 327, 964.CrossRefGoogle Scholar
Title, A.M., Tarbell, T.D., Simon, G.W., and the SOUP Team: 1986, Adv. Space Res. 6, 253.CrossRefGoogle Scholar
Title, A.M., Tarbell, T.D., Topka, K.P.: 1987, Ap. J. 317, 892.CrossRefGoogle Scholar
Title, A.M., Tarbell, T.D., Topka, K.P., Ferguson, S.H., Shine, R.A., and the SOUP Team: 1989, Ap. J. 336, 475.CrossRefGoogle Scholar
von der Lühe, O.: 1983, Astron. Astrophys. 119, 85.Google Scholar
Yi, Z.: 1992, Quiescent Filaments, Magnetic Field, and Flows in the Photosphere, Chapter 4 of , Google Scholar