Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000
We present the semi-empirical model of a powerful solar flare on July 19, 2000 based on spectral observations in the Fe I, Fe II, Cr I, and Ti II lines. Our calculations show the existence of a very narrow (≤ 100 km) and sharp magnetic field peak at photospheric level (log τ5 ≈ −2). It is possible t...
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| Zitieren: | Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 / E.V. Kurochka, V.G. Lozitsky // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 143-145. — Бібліогр.: 8 назв. — англ. |
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irk-123456789-796272015-04-04T03:02:06Z Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 Kurochka, E.V. Lozitsky, V.G. MS2: Physics of Solar Atmosphere We present the semi-empirical model of a powerful solar flare on July 19, 2000 based on spectral observations in the Fe I, Fe II, Cr I, and Ti II lines. Our calculations show the existence of a very narrow (≤ 100 km) and sharp magnetic field peak at photospheric level (log τ5 ≈ −2). It is possible that this peculiarity is indicative of the local magnetic field amplification due to specific process during the flare. Yet another interesting detail of the model is two discrete hot flare layers related to the middle photosphere and temperature minimum zone. 2005 Article Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 / E.V. Kurochka, V.G. Lozitsky // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 143-145. — Бібліогр.: 8 назв. — англ. 0233-7665 http://dspace.nbuv.gov.ua/handle/123456789/79627 en Кинематика и физика небесных тел Головна астрономічна обсерваторія НАН України |
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MS2: Physics of Solar Atmosphere MS2: Physics of Solar Atmosphere |
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MS2: Physics of Solar Atmosphere MS2: Physics of Solar Atmosphere Kurochka, E.V. Lozitsky, V.G. Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 Кинематика и физика небесных тел |
| description |
We present the semi-empirical model of a powerful solar flare on July 19, 2000 based on spectral observations in the Fe I, Fe II, Cr I, and Ti II lines. Our calculations show the existence of a very narrow (≤ 100 km) and sharp magnetic field peak at photospheric level (log τ5 ≈ −2). It is possible that this peculiarity is indicative of the local magnetic field amplification due to specific process during the flare. Yet another interesting detail of the model is two discrete hot flare layers related to the middle photosphere and temperature minimum zone. |
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Article |
| author |
Kurochka, E.V. Lozitsky, V.G. |
| author_facet |
Kurochka, E.V. Lozitsky, V.G. |
| author_sort |
Kurochka, E.V. |
| title |
Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 |
| title_short |
Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 |
| title_full |
Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 |
| title_fullStr |
Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 |
| title_full_unstemmed |
Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 |
| title_sort |
magnetic fields and thermodynamical conditions in the m6.4/3n solar flare on july 19, 2000 |
| publisher |
Головна астрономічна обсерваторія НАН України |
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2005 |
| topic_facet |
MS2: Physics of Solar Atmosphere |
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http://dspace.nbuv.gov.ua/handle/123456789/79627 |
| citation_txt |
Magnetic fields and thermodynamical conditions in the M6.4/3N solar flare on July 19, 2000 / E.V. Kurochka, V.G. Lozitsky // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 143-145. — Бібліогр.: 8 назв. — англ. |
| series |
Кинематика и физика небесных тел |
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2025-07-06T03:39:24Z |
| last_indexed |
2025-07-06T03:39:24Z |
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1836867298462269440 |
| fulltext |
MAGNETIC FIELDS AND THERMODYNAMICAL CONDITIONS
IN THE M6.4/3N SOLAR FLARE ON JULY 19, 2000
E. V. Kurochka, V. G. Lozitsky
Astronomical Observatory, National Taras Shevchenko University of Kyiv
3 Observatorna Str., 04053 Kyiv, Ukraine
e-mail: jane@observ.univ.kiev.ua, lozitsky@observ.univ.kiev.ua
We present the semi-empirical model of a powerful solar flare on July 19, 2000 based on spectral
observations in the Fe I, Fe II, Cr I, and Ti II lines. Our calculations show the existence of a very
narrow (≤ 100 km) and sharp magnetic field peak at photospheric level (log τ5 ≈ −2). It is possible
that this peculiarity is indicative of the local magnetic field amplification due to specific process
during the flare. Yet another interesting detail of the model is two discrete hot flare layers related
to the middle photosphere and temperature minimum zone.
INTRODUCTION
Solar flares are very attractive but complicated objects for magnetic field measurements. Due to essential
non-magnetic changes of the spectral lines during the flares, ordinary magnetographic measurements could give
unreliable data [7]. In order to obtain sufficiently reliable measurements, methods based on the full pictures of
the Stokes profiles are needed. Some of the following methods were proposed earlier in [2, 6, 7] for observations of
the 22nd solar activity cycle flares. In this work we analyse new data related to a flare of the current 23th cycle.
OBSERVATIONAL DATA AND SELECTED SPECTRAL LINES
Observational data were derived with the horizontal solar telescope of the Astronomical Observatory of the Kyiv
National Taras Shevchenko University. Table 1 gives selected spectral lines used in our investigation.
Table 1. List of spectral lines used and some their parameters
Element, N λ, Å EP, eV geff h, km r0
Fe I 816 6302.51 3.67 2.49 381 0.34
Fe I 816 6301.51 3.65 1.67 489 0.28
Fe I 686 5576.09 3.42 0 – 0.22
Fe I 66 5250.65 2.19 1.50 493 0.20
Fe I 1 5250.21 0.12 3.00 409 0.28
Fe I 1 5247.05 0.09 2.00 415 0.28
Fe II 49 5425.27 3.19 1.25 179 0.57
Fe II 35 5132.67 2.69 1.38 132 0.73
Fe II 42 4923.92 2.88 1.70 – 0.43
Ti II 69 5418.80 1.57 1.03 245 0.49
Cr I 18 5247.56 0.96 2.50 417 0.25
Fe I 16 5123.72 1.01 0 – 0.17
The flare had the coordinates 14◦ S and 15◦ E, and its importance was M6.4/3N. Ten echelle Zeeman-spectro-
grams of the flare were obtained from 6:54 to 8:30 UT, but here we study the spectrogram for 7:21 UT only,
which relates to time close to the flare peak. Many bright emissions in Balmer and metallic lines were observed,
but below we present the data related to the metallic emissions only. The following parameters are listed in
Table 1: N is the multiplet number, geff is effective Lande factor, h is the depth of line formation [5], and r0 is
the central intensity of lines from [4].
c© E. V. Kurochka, V. G. Lozitsky, 2004
143
SEMI-EMPIRICAL MODEL OF FLARE
Magnetic field measurements using the “centre of gravity” method show that an obvious dependence of the ef-
fective magnetic field Beff on magnetic sensitivity factor gλ2 takes place. This in an evidence for unresolved
elements with very strong (kG range) magnetic fields. For more concrete conclusions, model calculations similar
to presented earlier (in papers pointed above [7]) are needed.
The flare model was calculated using Baranovsky’s program [1] and twelve lines listed in Table 1. The model C
(average quiet Sun) from [8] was used as initial undisturbed photosphere. Calculations were made for two cases:
i) taking into account lines both of ionized and neutral atoms and ii) for neutral lines only.
According to the calculations, there are two maxima on the distribution of the flare temperature with
the atmosphere height (Fig. 1). In the first one temperature increased to 6560 K and in the second one to
5500 K. Exactly, if we keep the data for neutral lines only, the flare temperature decreases by 500 K in the first
temperature maximum, which is determined by the Fe II λ 492.39 nm line intensity. The temperature minimum
between them is 4400 K, which is 200 K less than in undisturbed model.
Figure 1. Temperature distribution of the undisturbed photosphere model (thin line), flare (thick line), and flare in case
of contribution of neutral lines only (dashed line)
Other flare parameters, such as hydrogen density and turbulent velocity, are changed as well. The density
does not change in the second case, but decreases in the first temperature maximum region by half order.
Turbulent flare velocity distribution has a maximum of 6.60 km/s, six times more than in undisturbed model.
Flare extent is approximately 450 km, undisturbed model is 650 km. So, the flare is more compact, hot, and
turbulent.
Figure 2 illustrates the most interesting peculiarity of the model. We can see a sharp narrow peak of
magnetic field with scale width about 90 km in the region of the flare temperature minimum. The magnetic
strength peak is 1600 G, and it is determined mainly by the Fe I λ 525.02 nm line width. This value corresponds
to the measurements using the “centre of gravity” method.
Figure 2. Magnetic field distribution of the flare model for the case when the angle between line of sight and field
vector is 30◦
144
CONCLUSIONS
The temperature flare model in comparison with undisturbed photosphere consists of two temperature maxima
and the minimum between them.
The density decrease coexists with the first temperature maximum, and increase with the temperature
minimum.
Turbulent velocity increased to 7 km/s in comparison with undisturbed photosphere model. The velocity
distribution was determined mainly by the Fe II λ 492.3 nm line wings.
Maximum of the magnetic field coexists with the temperature minimum. The magnetic field value reached
160 mT in about 100 km interval and had sudden increase and decrease. Without such sudden changes the Fe II
λ 492.3 nm and Fe I λ 513.22 nm line widths should be very large.
Above presented magnetic field peculiarity on log τ5 ≈ −2 (Fig. 1) is in surprisingly good agreement
with [2, 6, 7] for other flares. As to details, in our case the field peak is more narrow and places deeper in
atmosphere than it was found in [2, 6, 7]. In addition, conclusions 1–3 are in good agreement with the main
features of the flare model considered by Chornogor and Alikaeva [3].
Acknowledgements. We are very grateful to Dr. E. A. Baranovsky for placing his program at our disposal.
[1] Baranovsky E. A. Semiempirical LTE modelling of solar photospheric layers. I. Theoretical background // Contrib.
Astron. Obs. Skalnate Pleso.–1993.–23.–P. 107–117.
[2] Baranovsky E. A., Lozitska N. I., Lozitsky V. G. Magnetic fields and thermodynamical conditions in solar flare of
8 June 1989 // Kinematics and Physics of Celestial Bodies.–1991.–7, N 3.–P. 52–58.
[3] Chornogor S. M. State of the low-temperatures layers in solar flare loops.–Ph. D. Thesis.–Kyiv, 2004.–20 p.
[4] Delbouille L., Neven L., Roland G. Photometric atlas of the solar spectrum from 3000 to 10000.–Liege, 1973.
[5] Gurtovenko E. A., Kostik R. I. Fraunhofer spectrum and system of the solar oscillator strengths.–Kiev: Naukova
Dumka, 1989.–196 p.
[6] Lozitsky V. G., Baranovsky E. A. Determination of magnetic field and thermodynamical parameters of solar flare //
Izv. Krim. Astrofiz. Obs.–1993.–88.–P. 67–72.
[7] Lozitsky V. G., Baranovsky E. A., Lozitska N. I., Leiko U. M. Observations of magnetic field evolution in a solar
flare // Solar Phys.–2000.–191.–P. 171–183.
[8] Vernazza J. E., Avrett E. H., Loesser R. Structure of the solar chromosphere. III. Model of the EUV brightness
components of the quiet Sun // Astrophys. J. Suppl. Ser.–1981.–45.–P. 635–725.
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