Abnormal Stokes profiles of the photospheric lines in the region of chromospheric dual flows in the surroundings of a solar pore. II. Photospheric models
|1Kondrashova, NN |
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
|Kinemat. fiz. nebesnyh tel (Online) 2018, 34(4):30-52|
|Start Page: Solar Physics|
The thermodynamic parameters and parameters of the photospheric magnetic field in the region of chromospheric dual flows in the vicinity of a small pore in the active region NOAA 11024 are presented. Dual chromospheric flows have appeared in the region of anomalous Stokes V profiles of the photospheric lines and were associated with the emergence of a new small-scale magnetic flux of positive polarity. Semi-empirical photospheric models were obtained by inversion using the SIR program (Stokes Inversion based on Response functions) [Ruiz Cobo, del Toro Iniesta. Astrophys. J. 1992. 398. P. 375]. Each model contains two components: two thin magnetic flux tubes of different polarity. In the first component, the magnetic flux has a negative polarity, in the second component it is positive. Stokes profiles of the photospheric lines Fe I λ 630.15, 630.25 nm, 630.35 nm and Ti I λ 630.38 nm from spectropolarimetric observations with the French-Italian telescope THEMIS (Tenerife, Spain) were used for modeling. The height dependences of the temperature, the line-of-sight velocity, the angle of inclination of the magnetic field vector and the azimuth angle in the tubes, as well as the values of the magnetic field strength and the macroturbulent velocity are obtained. Time variations in all parameters of the photosphere are revealed. The new magnetic flux emerged in the region of mixed polarities and was accompanied by the warming of the photosphere and the chromosphere. The inferred flux tube models show the temperature enhancement up to 400 K in the upper photospheric layers relative to the quiet-Sun model temperature. They indicate a complex, inhomogeneous small-scale structure of the magnetic field and the velocity field. The magnetic field strength in the tubes varies from 0.03 to 0.13 T during the period under consideration. The angles of the inclination of the magnetic field vector and the azimuth angles strongly differ in magnetic flux tubes and vary in time. The line-of-sight velocity does not exceed 2 km/s. The downflows in the lower layers of the photosphere and the upflows in the upper layers are dominated in the first component of the models. In the second component of the model, the material is lifted in the upper photosphere. The macroturbulent velocity in most cases exceeds its value for the unperturbed photosphere. The velocity is greater in the second component of the models. The emergence of the new magnetic flux could lead to the magnetic reconnection and occurrence of a microflare.
|Keywords: active regions, magnetic fields, photosphere, spectropolarimetry, the Sun|
1.P. N. Bernasconi, S. U. Keller, S. K. Solanki, and J. O. Stenflo, “Complex magnetic fields in an active region,” Astron. Astrophys. 329, 704–720 (1998).
2.J. J. Brants, “High-resolution spectroscopy of active regions. III — Relations between the intensity, velocity, and magnetic structure in an emerging flux region,” Sol. Phys. 98, 197–217 (1985).
3.D. Buöhler, A. Lagg, S. K. Solanki, and M. van Noort, “Properties of solar plage from a spatially coupled inversion of Hinode SP data,” Astron. Astrophys. 576, A27 (2015).
4.T. A. Carroll and M. Kopf, “The meso-structured magnetic atmosphere. A stochastic polarized radiative transfer approach,” Astron. Astrophys. 468, 323–339 (2007).
5.R. Centeno, J. Blanco Rodríguez, J. C. Del Togo Iniesta, et al., “A tale of two emergences: Sunrise II observations of emergence sites in a solar active region,” Astrophys. J. Suppl. Ser. 229, 3 (2017).
6.R. Centeno, H. Socas-Navarro, B. Lites, et al., “Emergence of small-scale magnetic loops in the quiet-Sun internetwork,” Astrophys. J. 666, L137–L140 (2007).
7.D. P. Choudhary and K. S. Balasubramaniam, “Multiheight properties of moving magnetic features,” Astrophys J. 664, 1228–1233 (2007).
8.S. Danilovic, B. Beeck, A. Pietarila, et al., “Transverse component of the magnetic field in the solar photosphere observed by SUNRISE,” Astrophys. J. Lett. 723, L149–L153 (2010).
9.D. Degenhardt, “Stationary siphon flows in thin magnetic flux tubes. II — Radiative heat exchange with the surroundings,” Astron. Astrophys. 248, 637–646 (1991).
10.W. Deinzer, G. Hensler, M. Schüssler, and E. Weisshaar, “Model calculations of magnetic flux tubes. I. Equations and method,” Astron. Astrophys. 139, 426–434 (1984).
11.W. Deinzer, G. Hensler, M. Schussler, and E. Weisshaar, “Model calculations of magnetic flux tubes. II. Stationary results for solar magnetic elements,” Astron. Astrophys. 139, 435–449 (1984).
12.I. Dominguez Cerdeña, J. Sánchez Almeida, and F. Kneer, “Quiet Sun magnetic fields from simultaneous inversions of visible and infrared spectropolarimetric observations,” Astrophys. J. 646, 1421–1435 (2006).
13.C. E. Fischer, C. U. Keller, F. Snik, et al., “Unusual Stokes V profiles during flaring activity of a delta sunspot,” Astron. Astrophys. 547, A34 (2012).
14.M. Franz, M. Collados, C. Bethge, et al., “Magnetic fields of opposite polarity in sunspot penumbrae,” Astron. Astrophys. 596, A4 (2016).
15.M. Franz and R. Schlichenmaier, “The velocity field of sunspot penumbrae. II. Return flow and magnetic fields of opposite polarity,” Astron. Astrophys. 550, A97 (2013).
16.E. N. Frazier and J. O. Stenflo, “On the small-scale structure of solar magnetic fields,” Sol. Phys. 27, 330–346 (1972).
17.A. S. Gadun, S. K. Solanki, V. A. Sheminova, and S. R. O. Ploner, “A formation mechanism of magnetic elements in regions of mixed polarity,” Sol. Phys. 203, 1–7 (2001).
18.O. Gingerich, R. W. Noyes, W. Kalkofen, and Y. Cuny, “The Harvard–Smithsonian Reference Atmosphere,” Sol. Phys. 18, 347–365 (1971).
19.P. Gomory, C. Beck, H. Balthasar, et al., “Magnetic loop emergence within a granule,” Astron. Astrophys. 511, A14 (2010).
20.U. Grossmann-Doerth, M. Schussler, M. Sigwarth, and O. Steiner, “Strong Stokes V asymmetries of photospheric spectral lines: What can they tell us about the magnetic field structure?,” Astron. Astrophys. 357, 351–358 (2000).
21.S. L. Guglielmino, V. Martinez Pillet, J. A. Bonet, et al., “The frontier between small-scale bipoles and ephemeral regions in the solar photosphere: emergence and decay of an intermediate-scale bipole observed with SUNRISE/IMaX,” Astrophys. J. 745, 160 (2012).
22.S. S. Hasan, “Convective instability in a solar flux tube. II. Nonlinear calculations with horizontal radiative heat transport and finite viscosity,” Astron. Astrophys. 143, 39–45 (1985).
23.R. Ishikawa and S. Tsuneta, “Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun,” Astron. Astrophys. 495, 607–612 (2009).
24.R. Ishikawa, S. Tsuneta, K. Ichimoto, et al., “Transient horizontal magnetic fields in solar plage regions,” Astron. Astrophys. 481, 25–28 (2008).
25.E. V. Khomenko, M. Collados, S. K. Solanki, et al., “Quiet-Sun inter-network magnetic fields observed in the infrared,” Astron. Astrophys. 408, 1115–1135 (2003).
26.E. V. Khomenko, S. Shelyag, S. K. Solanki, and A. Vögler, “Stokes diagnostics of simulations of magnetoconvection of mixed-polarity quiet-Sun regions,” Astron. Astrophys. 442, 1059–1078 (2005).
27.N. N. Kondrashova, “Abnormal Stokes profiles of the photospheric lines in the region of chromospheric dual flows in the surroundings of a solar pore,” Kinematics Phys. Celestial Bodies 34, 53–67 (2018).
28.M. Kubo, B. Chye Low, and B. W. Lites, “Unresolved mixed polarity magnetic fields at flux cancellation site in solar photosphere at 0.3'' spatial resolution,” Astrophys. J. Lett. 793, L9 (2014).
29.A. Lagg, S. K. Solanki, H.-P. Doerr, et al., “Probing deep photospheric layers of the quiet Sun with high magnetic sensitivity,” Astron. Astrophys. 596, A6 (2016).
30.U. M. Leiko and N. N. Kondrashova, “The chromospheric line-of-sight velocity variations in a solar microflare,” Adv. Space Res. 55, 886–890 (2015).
31.U. M. Leiko and N. N. Kondrashova, “Dual chromospheric flows in the vicinity of a small pore,” Kinematics Phys. Celestial Bodies 33, 111–121 (2017).
32.B. W. Lites, A. Skumanich, and V. Martínez Pillet, “Vector magnetic fields of emerging solar flux. I. Properties at the site of emergence,” Astron. Astrophys. 333, 1053–1068 (1998).
33.M. J. Martínez González and L. R. Bellot Rubio, “Emergence of small-scale magnetic loops through the quiet solar atmosphere,” Astrophys. J. 700, 1391–1403 (2009).
34.M. J. Martínez González, L. R. Bellot Rubio, S. K. Solanki, et al., “Resolving the internal magnetic structure of the solar network,” Astrophys. J. Lett. 758, L40 (2012).
35.G. Narayan, “Transient downflows associated with the intensification of small-scale magnetic features and bright point formation,” Astron. Astrophys. 529, A79 (2011).
36.V. A. Osherovich, “A new magneto-hydrostatic theory of sunspots,” Sol. Phys. 77, 63–68 (1982).
37.S. R. O. Ploner, M. Schüssler, S. K. Solanki, et al., “The formation of one-lobed Stokes V profiles in an inhomogeneous atmosphere,” in Proc. Advanced Solar Polarimetry — Theory, Observation, and Instrumentation, Ed. by M. Sigwarth (Astronomical Society of the Pacific, San Francisco, 2001) in Ser.: ASP Conference Proceedings, Vol. 236, pp. 371–378.
38.C. Quintero Noda, J. M. Borrero, D. Orozco Suarez, and B. Ruiz Cobo, “High speed magnetized flows in the quiet Sun,” Astron. Astrophys. 569, A73 (2014).
39.R. Rezaei, R. Schlichenmaier, W. Schmidt, and O. Steiner, “Opposite magnetic polarity of two photospheric lines in single spectrum of the quiet Sun,” Astron. Astrophys. 469, L9–L12 (2007).
40.I. Rüedi, S. K. Solanki, W. Livingston, and J. O. Stenflo, “Infrared lines as probes of solar magnetic features. III. Strong and weak magnetic fields in plages,” Astron. Astrophys. 263, 323–338 (1992).
41.I. Rüedi, S. K. Solanki, and D. Rabin, “Infrared lines as probes of solar magnetic features. IV. Discovery of a sifon flows,” Astron. Astrophys. 261, L21–L24 (1992).
42.B. Ruiz Cobo and J. C. del Toro Iniesta, “Inversion of Stokes profiles,” Astrophys. J. 398, 375–385 (1992).
43.A. Sainz Dalda, J. Martinez-Sykora, L. Bellot Rubio, and A. Title, “Study of single-lobed circular polarization profiles in the quiet Sun,” Astrophys. J. 748, 38 (2012).
44.J. Sánchez Almeida, E. Landi Degl’Innocenti, V. Martínez Pillet, and B. W. Lites, “Line asymmetries and the microstructure of photospheric magnetic fields,” Astrophys. J. 466, 537–548 (1996).
45.J. Sánchez Almeida and B. W. Lites, “Physical properties of the solar magnetic photosphere under the MISMA hypothesis. II. Network and internetwork fields at the disk center,” Astrophys. J. 532, 1215–1229 (2000).
46.K. Sankarasubramanian and T. Rimmele, “Bisector analysis of Stokes profiles: Effects due to gradients in the physical parameters,” Astrophys. J. 576, 1048–1063 (2002).
47.G. B. Scharmer, J. de la Cruz Rodriguez, P. Sütterlin, and V. M. J. Henriques, “Opposite polarity field with convective downflow and its relation to magnetic spines in a sunspot penumbra,” Astron. Astrophys. 553, A63 (2013).
48.N. Shchukina and J. Trujillo Bueno, “The iron line formation problem in three-dimensional hydrodynamic models of solar-like photospheres,” Astrophys. J. 550, 970–990 (2001).
49.V. A. Sheminova, “On the origin of the extremely asymmetric Stokes V profiles in an inhomogeneous atmosphere,” (2005). arXiv 0902.2940
50.T. Shimizu, B. W. Lites, Y. Katsukawa, et al., “Frequent occurrence of high-speed local mass downflows on the solar surface,” Astrophys. J. 680, 1467–1476 (2008).
51.M. Sigwarth, “Properties and origin of asymmetric and unusual Stokes V profiles observed in solar magnetic fields,” Astrophys. J. 563, 1031–1044 (2001).
52.M. Sigwarth, K. S. Balasubramaniam, M. Knölker, and W. Schmidt, “Dynamics of solar magnetic elements,” Astron. Astrophys. 349, 941–955 (1999).
53.H. C. Spruit, “Convective collapse of flux tubes,” Sol. Phys. 61, 363–378 (1979).
54.O. Steiner, G. W. Pneuman, and J. O. Stenflo, “Numerical models for solar magnetic fluxtubes,” Astron. Astrophys. 170, 126–137 (1986).
55.J. O. Stenflo, “Magnetic-field structure of the photospheric network,” Sol. Phys. 32, 41–63 (1973).
56.J. O. Stenflo, “Small-scale solar magnetic fields,” in Proc. Basic Mechanisms of Solar Activity, 71st IAU Symp., Prague, Aug. 25–29, 1975, Ed. by V. Bumba and J. Kleczek (Reidel, Dordrecht, 1976), pp. 69–99.
57.J. H. Thomas, “Siphon flows in isolated magnetic flux tubes,” Astrophys. J. 333, 407–419 (1988).
58.J. H. Thomas and B. Montesinos, “Siphon flows in isolated magnetic flux tubes. IV — Critical flows with standing tube shocks,” Astrophys. J. 375, 404–413 (1991).
59.G. Valori, L. M. Green, P. Démoulin, et al., “Nonlinear force-free extrapolation of emerging flux with a global twist and serpentine fine structures,” Sol. Phys. 278, 73–97 (2012).
60.S. Vargas Domínguez, L. van Driel-Gesztelyi, and L. R. Bellot Rubio, “Granular-scale elementary flux emergence episodes in a solar active region,” Sol. Phys. 278, 99–120 (2012).
61.B. Viticchié, “On the polarimetric signature of emerging magnetic loops in the quiet Sun,” Astrophys. J. Lett. 747, L36 (2012).
62.B. Viticchié and J. Sánchez Almeida, “Asymmetries of the Stokes V profiles observed by HINODE SOT/SP in the quiet Sun,” Astron. Astrophys. 530, A14 (2011).
63.B. Viticchié, J. Sánchez Almeida, D. Del Moro, and F. Berrilli, “Interpretation of HINODE SOT/SP asymmetric Stokes profiles observed in the quiet Sun network and internetwork,” Astron. Astrophys. 526, A60 (2011).
64.Z. Xu, A. Lagg, and S. K. Solanki, “Magnetic structures of an emerging flux region in the solar photosphere and chromosphere,” Astron. Astrophys. 520, A77 (2010).
65.I. Zayer, S. K. Solanki, and J. O. Stenflo, “The internal magnetic field distribution and the diameters of solar magnetic elements,” Astron. Astrophys. 211, 463–475 (1989).