Physical conditions in the chromosphere of a solar two-ribbon flare accompanied by a surge. I

1Baranovskii, EA, 2Kondrashova, NN, 2Pasechnik, MN, 1Tarashchuk, VP
1Crimean Astrophysical Observatory, Nauchny, Ukraine
2Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2013, 29(4):18-30
Start Page: Solar Physics
Language: Russian

We study some variations of chromospheric thermodynamic parameters at the initial stage of the two-ribbon flare occurred on 4 September 1990 and accompanied by a surge. Nonhomogeneous semiempirical models of the flare chromosphere and surge were built for four moments of the flare observations. The spectra were obtained with the solar horizontal telescope ATsU-26 at the Terskol Peak Observatory. Two bright kernels of one of the ribbons and the surge were studied. Our comparison of the observed Нα line profiles with the quiet-Sun region line profile in the same position on the solar disk as the active region revealed some significant emission in the Нα line wings (up to 1...1.2 nm) at the residual intensity 0.6...0.77 in the Нα line centre. Our calculations in the framework of two-component chromospheric models point to a possible existence of some details with deep heating chromospheric layers. These details occupy 5...12 % of the total area and can not be resolved with a telescope. A strong asymmetry of the line profiles and the shift with respect to the quiet-Sun line profile can be interpreted by height distribution peculiarities of line-of-sight velocities. It is derived that for the majority of the active region outs under investigation the motion is directed to the observer in the upper chromosphere (10...30 km/s) and from the observer in the lower chromosphere (5...20 km/s). The models calculated for the surge give the value of line-of-sight velocities up to 70 km/s.

Keywords: chromosphere, solar flares, Sun

1.N. N. Kondrashova and M. N. Pasechnik, “Radial velocities of the photospheric matter in a solar flare with matter ejection,” Kinemat. Phys. Celest. Bodies 26, 26 (2010).

2.N. N. Kondrashova and M. N. Pasechnik, “Radial velocity field in the lower atmosphere of the solar active region during a flare with an ejection: The initial phase of the flare,” Kinemat. Phys. Celest. Bodies 27, 224 (2011).

3.M. N. Pasechnik, “Motion of chromospheric matter in the active region during a flare with ejection,” (Visn. Kiv. Nats. Un-Tu Im. Tarasa Shevchenka. Astronomiya, Kiev, 2003) [In Ukrainian].

4.G. A. Porfir’eva, G. V. Yakunina, and A. B. Delone, “Flares and filament activation in active regions on the Sun,” Solnechno-Zemnaya Fizika, No. 12-1, 6 (2008).

5.E. Priest, Solar magnetohydrodynamics (Reidel, Dordrecht, Netherlands, 1982; Mir, Moscow, 1985).

6.E. H. Avrett and R. Loeser, “Formation of line and continuous spectra. I. Source-function calculations,” Spec. Report SAO, No. 303 (1969).

7.D. H. Brooks, H. Kurokawa, and T. E. Berger, “An Hα surge provoked by moving magnetic features near an emerging flux region,” Astrophys. J. 656(2), 1197–1207 (2007).

8.R. C. Canfield, K. P. Reardon, K. D. Leka, et al., “Hα-Surges and X-Ray Jets in AR 7260,” Astrophys. J. 464(2), 1016–1029 (1996).

9.J. Chae, J. Qiu, H. Wang, and P. R. Goode, “Extreme-ultraviolet jets and Hα surges in solar microflares,” Astrophys. J. 513, L75–L78 (1999).

10.J. Y. Ding, M. S. Madjarska, J. G. Doyle, et al., “Magnetic reconnection resulting from flux emergence: implications for jet formation in the lower solar atmosphere?,” Astron. Astrophys. 535, 1–10 (2011).

11.V. S. Gorbachev and B. V. Somov, “Photospheric vortex flows as a cause for two-ribbon flares. A topological model,” Solar Phys. 117(1), 77–88 (1988).

12.X. M. Gu, J. Lin, K. J. Li, et al., “Kinematic characteristics of the surge on March 19, 1989,” Astron. Astrophys. 282, 240–251 (1994).

13.S. L. Guglielmino, L. R. Bellot Rubio, F. Zuccarello, et al., “Multiwavelength observations of small-scale reconnection events triggered by magnetic flux emergence in the solar atmosphere,” Astrophys. J. 724, 1083–1098 (2010).

14.J. Heyvaerts, E. R. Priest, and D. M. Rust, “An emerging flux model for the solar flare phenomenon,” Astrophys. J. 216(1), 123–137 (1977).

15.D. E. Innes and G. Toth, “Simulations of small-scale explosive events on the Sun,” Solar. Phys 185(1), 127–141 (1999).

16.Y. C. Jiang, H. D. Chen, K. J. Li, et al., “The Hα surges and EUV jets from magnetic flux emergences and cancellations,” Astron. Astrophys. 469, 331–337 (2007).

17.P. Jibben and R. C. Canfield, “Twist propagation in Hα surges,” Astrophys. J. 610, 1129–1135 (2004).

18.R. A. Kopp and G. W. Pneuman, “Magnetic reconnection in the corona and the loop prominence phenomenon,” Solar Phys. 50(1), 85–98 (1976).

19.H. Kurokawa and G. Kawai, “Hα surge activity at the first stage of magnetic flux emergence,” in The magnetic and velocity fields of solar active regions, Ed. by H. Zirin, G. Ai, and H. Wang, (ASP Conf. Ser., San Francisco, 1993), Vol. 46, P. 507.

20.K. Li, J. Li, X. Gu, and S. H. Zhong, “A quantitative analysis of the surge on March 19, 1989,” Solar. Phys 168(1), 91–103 (1996).

21.Y. E. Litvinenko and J. Chae, “Signatures of Sweet-Parker magnetic reconnection in the solar chromosphere,” Astron. Astrophys. 495(3), 953–957 (2009).

22.W. Liu, T. E. Berger, A. M. Title, et al., “Chromospheric jet and growing ‘loop’ observed by Hinode: New evidence of fan-spine magnetic topology resulting from flux emergence,” Astrophys. J. 728(103), 1–16 (2011).

23.Yu. Liu and H. Kurokawa, “On a surge: properties of an emerging flux region,” Astrophys. J. 610, 1136–1147 (2004).

24.S. Morita, K. Shibata, S. Ueno, et al., “Observations of chromospheric anemone jets with Hinode Ca II broad band filtergraph and Hida Ca II spectroheliograph,” Publs Astron. Soc. Jap 62, 901–920 (2010).

25.G. Roumeliotis and R. L. Moore, “A linear solution for magnetic reconnection driven by converging or diverging footpoint motions,” Astrophys. J. 416(1), 386–391 (1993).

26.B. Schmieder, L. Golub, and S. K. Antiochos, “Comparison between cool and hot plasma behaviors of surges,” Astrophys. J. 425, 326–330 (1994).

27.Solar Geophys. Data 559, 2 (1991).

28.B. V. Somov, T. Kosugi, H. S. Hudson, et al., “Magnetic reconnection scenario of the Bastille day 2000 flare,” Astrophys. J. 579(2), 863–873 (2002).

29.K. Tziotziou, G. Tsiropoula, and P. Sitterlin, “DOT tomography of the solar atmosphere. V. Analysis of a surge from AR 10489,” Astron. Astrophys. 444, 265–274 (2005).

30.W. Uddin, B. Schmieder, R. Chandra, et al., “Observations of multiple surges associated with magnetic activities in AR 10484 on 25 October 2003,” Astrophys. J. 752(1), 1–10 (2012).

31.J. E. Vernazza, E. H. Avrett, and R. Loeser, “Structure of the solar chromosphere. III. Models of the EUV brightness components of the quiet Sun,” Astrophys. J., Suppl. Ser. 45(4), 635–725 (1981).

32.K. Yoshimura, H. Kurokawa, M. Shimojo, and R. Shine, “Close correlation among Hα surges, magnetic flux cancellations, and UV brightenings found at the edge of an emerging flux region,” Publs Astron. Soc. Jap 55(1), 312–320 (2003).

33.J. Zhang, J. Wang, and Y. Liu, “An Hβ surge and X-ray jet magnetic properties and velocity patterns,” Astron. Astrophys. 361, 759–765 (2000).