Semiempirical photospheric models of a solar flare on May 28, 2012

Andriets, E. S.; Kondrashova, N.

doi:10.1016/j.asr.2014.07.026

Cited by 3 publications

(2 citation statements)

References 31 publications

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“…In reality, it was shown that the magnetic field distribution versus height may be non-monotonous, with a narrow peak in the range of the upper photosphere [3,7]. In other flares such nonmonotonous changes were not observed [8][9][10]. A possible reason for this disagreement is that the character of the altitude distribution of the magnetic field in the area of a flare can depend on the phase of the development of the flare.…”

Section: Introductionmentioning

confidence: 99%

Magnetic fields and thermodynamical conditions at photospheric layers of X17.2/4B solar flare of 28 October 2003

Lozitsky¹,

Baranovsky²,

Lozitska³

et al. 2017

J. Phys. Stud.

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We present the magnetic field measurements and data of semi-empirical modeling for the exclusively powerful solar flare of 28 October 2003 of X17.2/4B class, which was in active region NOAA 0486. Observations were made with the Echelle spectrograph of the horizontal solar at telescope the Astronomical Observatory of the Taras Shevchenko National University of Kyiv. Our data relate to the peak phase of the flare and to a place of the photosphere outside sunspots.Nine spectral lines were selected for analysis, including such well known lines as FeI 5247.052, 5250.212, 6301.515, 6302.507Å, etc. Three "non-split" lines FeI 5123.723, 5434.527 and 5576.097Å were studied too (their effective Lande factors are, in fact, −0.013, −0.014 and −0.012, respectively).Magnetic field strengths in the flare were determined by three methods: (1) by splitting of the "center of gravity" of I ± V profiles; (2) by the amplitude of Stokes V profiles using "weak field approximation" and (3) using the PANDORA code, which allows to create the semi-empirical model of the flare.We found that in the brightes places of the flare the effective magnetic field B eff was 0-200 G in the middle photosphere (FeI 6302.5 and 5250.2 lines), 600-1200 G in the upper photosphere and temperature minimum zone (FeII 4923.9 and 5234.6 lines), and had S polarity.In the FeI 5434.527 line, the weak splitting of emission peaks near its core was observed; its value was 10-20 mÅ. If this splitting is interpreted as a manifestation of the Zeeman effect, then the corresponding magnetic field is about 25-50 kG. The magnetic polarity of this "superstrong" field should be N , i.e. opposite to the polarity of other FeI lines with greater Lande factors.A semi-empirical model of the flare was build with the PANDORA code, which allows to determine the magnetic field and thermodynamical conditions on both photospheric and chromospheric levels using non-LTE approximation. It was found that the magnetic field in the middle photosphere was 1000-1200 G. The temperature in the flare increased up to 1000 K for lg τ5 ≈ −3. Turbulent velocity vt is almost the same as in an undisturbed atmosphere, but in the range from lg τ5 = 1 to lg τ5 = −1; from lg τ5 = −1 to lg τ5 = −3 a sharp increase vt was found where vt reaches about 3.5 km/s.

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Section: Introductionmentioning

confidence: 99%

Magnetic fields and thermodynamical conditions at photospheric layers of X17.2/4B solar flare of 28 October 2003

Lozitsky¹,

Baranovsky²,

Lozitska³

et al. 2017

J. Phys. Stud.

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“…Напруженість магнітного поля зменшується з 0,12-0,18 Тл (log  = 0) до 0,055-0,11Тл (log  = -3). Низхідні потоки існували у фазі загасання спалаху [14]. спалахом швидкість висхідних потоків у верхній хромосфері змінювалася від 25 до 0 км/с.…”

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Joint studies of solar flares at the Astronomical observatory of Taras Shevchenko National University of Kyiv and the Main Astronomical observatory of the Academy of Science of Ukraine

Kondrashova¹

2021

BTSNUA

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Joint studies of changes in the photosphere and chromosphere before and during solar flares at the Astronomical Observatory of Taras Shevchenko Kyiv University and the Main Astronomical Observatory of the National Academy of Sciences of Ukraine are described. Observations of flaring-active regions were performed at solar horizontal telescopes of the GAO NASU Ernest Gurtovenko’s ATsU-5 in Kyiv, ACU-26 on the Terskol peak and at the French-Italian solar tower telescope THEMIS with the spectropolarimeter in the Canary Islands in Spain. Significant variations in the spectral lines formed in the photosphere due to flares have been detected. Some results of modeling of the photosphere and chromosphere before and during flares of different classes are given. Conclusions are made regarding the important role of the photosphere in the flare process, the sequence of propagation of flare perturbation in the lower layers of the solar atmosphere.

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Spectropolarimetric investigation of an Ellerman bomb: 1. Observations

Kondrashova

2016

Kinemat. Phys. Celest. Bodies

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Semiempirical photospheric models of a solar flare on May 28, 2012

Cited by 3 publications

References 31 publications

Magnetic fields and thermodynamical conditions at photospheric layers of X17.2/4B solar flare of 28 October 2003

Magnetic fields and thermodynamical conditions at photospheric layers of X17.2/4B solar flare of 28 October 2003

Joint studies of solar flares at the Astronomical observatory of Taras Shevchenko National University of Kyiv and the Main Astronomical observatory of the Academy of Science of Ukraine

Spectropolarimetric investigation of an Ellerman bomb: 1. Observations

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