What are solar faculae?

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1Kostyk, RI
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2013, 29(1):50-57
Start Page: Solar Physics
Language: Russian
Abstract: 

We present some results of observations of a facula area located near the solar disc center. The observations were performed at the German Vacuum Tower Telescope of the Observatorio del Teide (Tenerife) with the simultaneous use of two instruments: TESOS in the Ba II λ 455.4 nm line to measure intensity variations along the photosphere and TIP in the Fe I (λλ1564.3—1565.8 nm) line to measure Stokes parameters. Using the Fourier filtering procedure, we separated the convective and oscillatory components of intencity field. The Stokes parameters of the Fe I λ 1564.8 nm and λ 1565.2 nm lines were inverted using SIR inversion code to estimate the magnetic field intencity. We found that continuum facular contrast of intergranular lines was nearly constant as a function of magnetic field intencity (from 300 to 1600 gauss). This result casts some suspicion on the assertion that solar faculae are an accumulation of small magnetic flux tubes, but rather indicates that hot granular walls are seen due to some decrease of the matter transparency in the presence of strong (about 1 kgauss) magnetig field.

Keywords: magnetic field, solar faculae, Sun
References: 

1.T. E. Berger, L. H. M. Rouppe van der Voort, M. G. Lofdahl, et al., “Solar Magnetic Elements at 0.1” Resolution. General Appearance and Magnetic Structure,” Astron. Astrophys. 428, 613–628 (2004).
https://doi.org/10.1051/0004-6361:20040436

2.T. E. Berger, A. M. Title, T. D. Tarbell, et al., in Proc. ASP Conf. Ser, Kyoto, Japan, 2005, Ed. by K. Shibata, S. Nagata, and T. Sakurai (ASP, San Francisco, 2007), Vol. 369, pp. 103–111.

3.R. B. Dunn and J. B. Zirker, “The Solar Filigree,” Solar Phys. 33, 281–304 (1973).

4.E. N. Frazier, “Mult-Channel Magnetograph Observations. II Faculae,” Solar Phys. 21, 42–53 (1971).
https://doi.org/10.1007/BF00155772

5.U. Grossmann-Doerth, M. Knolker, M. Schussler, et al., “The Deep Layers of Solar Magnetic Elements, Astron. Astrophys. 285, 648–654 (1994).

6.E. Khomenko, R. I. Kostik, and N. G. Shchukina, “Five-Minute Oscillations above Granules and Intergranular Lanes,” Astron. Astrophys. 369(2), 660–671 (1994).
https://doi.org/10.1051/0004-6361:20010129

7.M. Knolker, M. Schuessler, and E. Weisshaar, “Model Calculations of Magnetic Flux Tubes. III. Properties of Solar Magnetic Elements,” Astron. Astrophys. 194, Nos. 1–2, 257–267 (1988).

8.P. Kobel, S. K. Solanki, and J. M. Borrero, “The Continuum Intensity as a Function of Magnetic Field. I. Active Region and Quiet Sun Magnetic Elements,” Astron. Astrophys. 531, A112–A124 (2011).
https://doi.org/10.1051/0004-6361/201016255

9.R. I. Kostik and E. Khomenko, “Observations of a Bright Plume in Solar Granulations,” Astron. Astrophys. 476(2), 341–347 (2007).
https://doi.org/10.1051/0004-6361:20077163

10.R. Kostik, E. Khomenko, and N. Shchukina, “Solar Granulation from Photosphere to Low Chromosphere Observed in Ba II 4554 Å Line,” Astron. Astrophys. 506(4), 1405–1415 (2009).
https://doi.org/10.1051/0004-6361/200912441

11.B. W. Lites, G. B. Sharmer, T. E. Berger, et al., “Three-Dimensional Structure of the Active Region Photosphere as Revealed by High Angular Resolution,” Solar Phys. 221(1), 65–84 (2004).
https://doi.org/10.1023/B:SOLA.0000033355.24845.5a

12.M. Montagne, R. Muller, and J. Vigneau, “The Photosphere of the Sun: Statistical Correlations between Magnetic Field, Intensity and Velocity,” Astron. Astrophys. 311, 304–310 (1996).

13.G. Narayan and G. B. Scharmer, “Small-Scale Convection Signatures Associated with a Strong Plage Solar Magnetic Field,” Astron. Astrophys. 524, A3–A19 (2010).
https://doi.org/10.1051/0004-6361/201014956

14.O. V. Okunev and F. Kneer, “Numerical Modeling of Solar Faculae Close to the Limb,” Astron. Astrophys. 439, 323–334 (2005).
https://doi.org/10.1051/0004-6361:20052879

15.B. Ruiz Cobo and J. C. del Toro Iniesta, “Inversion of Stokes Profiles,” Astrophys. J. 398(1), 375–385 (1992).
https://doi.org/10.1086/171862

16.E. H. Schroter, D. Soltau, and E. Wiehr, “The German Solar Telescopes at the Observatorio del Teide,” Vistas Astron. 28(3), 519–525 (1985).
https://doi.org/10.1016/0083-6656(85)90073-X

17.H. C. Spruit, “Pressure Equilibrium and Energy Balance of Small Photospheric Fluxtubes,” Solar Phys. 50, 269–295 (1976).
https://doi.org/10.1007/BF00155292

18.R. T. Stebbins and P. R. Goode, “Waves in the Solar Photosphere,” Solar Phys. 110(2), 237–253 (1987).
https://doi.org/10.1007/BF00206421

19.O. Steiner, “Radiative Properties of Magnetic Elements. II. Center to Limb Variation of the Appearance of Photospheric Faculae,” Astron. Astrophys. 430, 691–700 (2005).
https://doi.org/10.1051/0004-6361:20041286

20.J. O. Stenflo, “Magnetic-Field Structure of the Photospheric Network,” Solar Phys. 32(1), 41–63 (1973).
https://doi.org/10.1007/BF00152728

21.A. M. Title, K. P. Topka, T. D. Tarbell, et al., “On the Differences between Plage and Quiet Sun in the Solar Photosphere,” Astrophys. J. 393, 782–794 (1992).
https://doi.org/10.1086/171545

22.K. P. Topka, T. D. Tarbell, and A. M. Title, “Properties of the Smallest Solar Magnetic Elements. I. Facular Contrast near Sun Center,” Astrophys. J. 396, 351–363 (1992).
https://doi.org/10.1086/171721

23.K. P. Topka, T. D. Tarbell, and A. M. Title, “Properties of the Smallest Solar Magnetic Elements. II. Observations Versus Hot Wall Models of Faculae,” Astrophys. J. 484, 479–486 (1997).
https://doi.org/10.1086/304295