DYNAMICDYNAMIC OF ELECTROMAGNETIC OF ELECTROMAGNETIC

EMISSION DURING THE PERIOD EMISSION DURING THE PERIOD

OF SOLAR EXTREME EVENTSOF SOLAR EXTREME EVENTS

M.S.Durasova, M.S.Durasova, V.M.FridmanV.M.Fridman, T.S.Podstrigach, , T.S.Podstrigach, O.A.SheinerO.A.Sheiner, S.D.Snegirev, Yu.V.Tikhomirov, S.D.Snegirev, Yu.V.Tikhomirov

Radiophysical Research Institute, Nizhny Novgorod, Russiarfj@nirfi.sci-nnov.ru

The work is carried out with the support of Russian Fund for Basic Research (grant 03-02-16691) and FPSTP (Astronomy).

This work is devoted to study the behavior This work is devoted to study the behavior of solar emission during the period of of solar emission during the period of January 2005. The analysis is based upon January 2005. The analysis is based upon observations made with Radio telescopes in observations made with Radio telescopes in the out-of-town observatory NIRFI the out-of-town observatory NIRFI “Zimenki”.“Zimenki”.

These are monitoring observations of solar These are monitoring observations of solar radio emission in cm-dm frequency range: radio emission in cm-dm frequency range: 9114 MHz, 2950 MHz, and 900 MHz.9114 MHz, 2950 MHz, and 900 MHz.

Processes leading to main solar events start Processes leading to main solar events start to be visible in solar radio emission during 2-to be visible in solar radio emission during 2-3 days 3 days

before the events.before the events.

• Effect of the growth of long-period pulsations with a period of more than 20 minutes in the cm solar radio emission 2-3 days before proton flares has been discovered before proton flares in the events of August 1972 (Kobrin, et al. 1973) and later was confirmed, using specially developed equipment in observations (Semenova, 1987).

• The possibilities of this procedure realization with the use of routine solar observational data are examined for 4 powerful flares of January, 2005.

• Figures 1, 2, and 6 ─ behaviour of solar radio emission during calm periods far away from solar flares, presented in different scales. There are no distinctive pulsation in radio emission.

• Figures 3, 4, and 5 present the growth of amplitude of long-period pulsations with a period of more than 20 minutes before main flares (the scale is the same as in Fig.2).

Fig.1

Fig.2

Fig.6

Fig.3

Fig.4

Fig.5

• The interval following the previous one coincide with periods preceding CMEs and flare registration. It was established earlier that sporadic events in solar radio emission accompanied CMEs formation.

• Tables 1 and 2 contain the list of sporadic components of radio emission called microwave precursors for January 17 and 19, 2005.

• As we see from the Tables during the time interval of 1.5h on January 17 and 1h on January 19 one can see such small events as simple impulsive C, simultaneous numerous frequencies GRF, RF or SER.

• Most of sporadic events are broad-band, because of they are observed in all used frequencies.

• This fact is the confirmation of preliminary formulated rules.

January 17,January 17, 200 20055

January 19,January 19, 200 20055

• Both of these events (January 17 and 19, 2005) are accompanied by Halo type CMEs. There were events with extremely high speed: more than 2000 km/s.

• On January 19 the burst is ahead the CMEs registration on 30 min, and on January 17 this interval is about 48 min. The last fact cannot be explained as initial CMEs propagation in solar atmosphere because of very high speed of CMEs. The phenomenon of CMEs’ output seems to be during sharp growth of radioemission.

Fig.1

Fig.3

Fig.2

Fig.5

Fig.4

Fig.6

Figures 1-6 present power spectrum of solar radio flux in different time before the main energy release. Figs. 1 and 2 ─ in 100 min;Figs. 3 and 4 ─ in 60 min;Figs. 5 and 6 ─ in 50 min.As it is seen from the pictures the earlier observations the noisy behavior of spectrum. Whereas the closer to the main phase of the burst the bigger amplitude of spectral component with observing allocated periods of about 14-22 s. To compare the behavior of components analogous results are presented in Figs.7 and 8 obtained during the falling part of burst.

Fig.7 Fig.8Fig.9

ConclusionConclusion

Obtained results illustrates long-term (several days) dynamics of solar radio emission connected with developing preflare activity using the possibilities of the stationary routine observations.

• Kobrin M.M., A.I. Korshunov, S.D. Snegirev, B. V. Timofeev, On a Sharp Increase of Quasi-Periodic Components of Inclination of the Solar Radio Emission Spectrum at 3 cm Before the Active Events in August 1972, Solnechnye dannye [in Russian], N 10, 79, 1973.

• Semenova S.V., V.M.Fridman, O.A.Sheiner, et al. About the Possibility of Creation the Methodic of Short-Term Prediction for Solar Proton Flares on the Base of Long-Period Pulsations of Solar Radio Emission, Preprint NIRFI[in Russian], N228, Gorky, 1987.