It has been established that the bursts of the type III decimeter are generated in the upper crown by electron beams. However, there are many questions about their sources to this day. Some associated with the airplanes generated by regular solar flares, but most were associated with weak energy release events. The purpose of this work is to determine the relationship of the bursts of the type of meter and decimeter III with the eruption of plasma in the thermal phase of the Bengal. We analyze in detail the Bengal of June 29, 2012, using multiwave observations. This event is unusual because for a few minutes there is a thermal plasma output with high temperatures up to 12 mk when there is still no response in microwave or hard x -rays.
Observations
The outbreak of June 29, 2012 occurred at 04: 09–04: 16 UT (hereinafter, the universal time is used) in the active region #11515; The class of flashes according to Goes is C4.6. Figure 1 presents light curves of the Bengal in radiographs, decimeter and microwave radiation.
EUV images show that the energy release of the Bengal occurs in low loops (flash nucleus in Figure 2) located at the foot points of a large -scale loop and open field lines. A high loop is observed before the Bengal. At 04:09, compact toasts appeared in the SDO/AIA images on channel 304 Å. A minute later, at 04:10, the plasma began to flow along open field lines from west to this in the plane of the sky (Figure 3). Over time, the brightness of these plasma jets increased. Another stream arose in a high circuit closed and gradually reached the remote western point of the circuit.
Figure 1. Event of June 29, 2012: A-Go, radiation flows (solid curve-0.5–4 Å, Dash-Dot-1–8 Å); B – HXR time profiles on the 25–50 Kev Rossi channels; C, D – Dynamic spectra (Hiras); E – Integral intensity of radius emission from 50 to 550 MHz (solid curve). The speeds of the heat wave fronts are propagated along the open magnetic field lines (see Figure 4) are indicated by asterisks. The dotted lines mark the time of the beginning of the radio explosions, the board points line on both panels indicates the beginning of a hard x -ray explosion (04:13:23).
Figure 2. Large -scale structure of a region of flashes. The background is the difference between the images captured at 04:12:11 and 04:09:35 on the AIA/SDO 131 å channel. The nucleus of the Bengal, the jet (spray) and the high loop, along which another jet moved.
The dynamics of the southern jet, along the trajectory from which the blue white line is drawn, is shown in the sequence of images in channel 304 Å (see figure 3). It can be seen from brightness profiles (Figure 3) that during the spread of hot plasma flow there is no gradual increase characteristic of diffusion, but a soaking of ~ 6“ in size at the beginning of the jet, which can be interpreted as a quasi-stational thermal front. The frontal profiles are seen the brightness distributions along the open magnetic lines (Figure 3). The front speeds reach 300-500 km/s.
Figure 3. Images on the AIA/SDO 304 Å channel for the given time points. The white dashboard lines mark the horizontal cross section of the image. The brightness profile throughout the cross section is highlighted blank at the bottom of each panel. The blue discontinuous line connects fronts (shine jumps) of the propagation jet. Throughout the XEY axes, the values occur in pixels.
Discussion and conclusion
In the case of study, hot plasma with temperatures above 10 mk appears in the initial stage of the Bengal, and an explosion of non -thermal electrons is observed a few minutes later. A characteristic of this event is plasma heating at an abnormally high temperature in the nucleus of the Bengal, as well as close to the foot points of the large -scale loops, which creates favorable conditions to study heat and spread of Plasma in the upper crown.
The SDO/AIA images suggest that part of the heated plasma moves from the hot nucleus along the open field lines, and another part is spread along the high loops (closed in the field of vision) to standing points remote The behavior of EUV-BRIGHTNESS distributions was examined along the open field line aligned by latitude (see Fig. 2). During ~ 5 minutes from the appearance of the jet to the end of the impulsive phase, there were four sequentially propagated toasts with a width front ~ 4–5 thousand km during the plasma output (Fig. 3). The fronts separated from the hot nucleus of the flaws and moved at speeds of 300–500 km/s, which at a 10 mk plasma temperature are 30-40 times lower than the thermal speed of the electrons, but several times more times high than the thermal speed of ions.
The slowdown in the propagation of hot electron clusters in cold plasma was previously observed in laboratory experiments. In Bengala, this effect was first observed in [Batchelor et al., 1985; Rust et al., 1985]. A theoretical explanation was discussed for the formation of a heat leap between hot and cold plasmas at a much lower speed than the thermal speed of electrons [Bardakov 1985]. The electrons dispersed due to the compensation of a outgoing load by the cold electron counter since the ions do not have time to move.
The Bengal of June 29, 2012 did not see any Neupert effect, that is, this flare was a preheating event observed in soft radiographs before the impulsive phase, which was later detected in hard X -rays. When hot density electrons are high enough along the magnetic field in an environmental plasma, quasi-movement are formed periodically in the density of hot electrons, which can be associated with brightness fronts in EUV images. The most energetic electrons exceed the electrical potential Salta and generate the beams and, as results, emission pulses of the decimeter.
The formation of such fronts is not observed when the jet extends along a high loop. This confirms the continuity of the flow of hot electrons of the core of the Bengal. Perhaps the relative flow density of the hot electron along the high circuit is too small to induce a flow of against the electrons of sufficiently high speed.
Based on the recent article: Altyntsev, AT, Meshalkina, NS Manifestation of heating at the beginning of the outbreak of June 29, 2012: 2024, solar-terrestrial physics, 10 (3), p.11-17, doi: 10.12737/STP-103202402.
References
- Batchelor A., Crannell CJ; Wiehl HJ, Magun A. 1985, Astrophys. J. 295, 258.
- Rust M., Simnett GM, Smith DF 1985, Astrophys. J., 288, 401.
- Bardakov VM: 1985, Physika Plasmy, 11 (10), 1223
#Generation #MetroDecimeter #III #type #burst
