TRACE and RHESSI observations of failed eruption of magnetic flux rope

and oscillating coronal loops

Tomasz MrozekAstronomical InstituteUniversity of Wrocław

The flare

M6.2 GOES classN14 W61

RHESSI: entire event

TRACE: 171 Å (several seconds

cadence)1600 Å (several cadence,

decay phase)

GOES SXI: several, saturated images

SOHO LASCO:no CME reported

The flare

GOES class M6.2 event connected with small (less than 104 km) arcade of loops.

Clearly associated with the eruption of the magnetic structure.

Evolution of the eruption

Initial phase connected with small brightenings in the HXRs

1Fast evolutionfollowing the strongest HXR peak visible in 25-50 keVrange

2

Deceleration phase. Main front changes its shape. Side eruptions areobserved

3

25-50 keV

H[k

m]

Higher in the corona…

Above the erupting structure we observed the system of loops.

These loops changes their height as the eruption evolves.

The shape of the eruption front shows that „something”stopped the ejection.

Side eruptions suggestthat such breaking does not take place on theboth sides of the high-lying loops

Interaction

High-lying loops started to rise

The end of the foremost eruption(and the end of the force driving the movement of the high-lying loops)

Oscillating loops

Oscillating loops

The same height before and after oscillations

Global oscillations of coronal loops

Radial, transversalChange of radius

One observation (Wang & Solanki 2004)

Tangential, horizontalNo change of radius

About 20 observations reported by several authors

14 Jul 2004 event

0

t

HetP

2sinA)t(H

Observed oscillations are well described with the use of dumped sine function.

Similar parameters to these obtained by Wang and Solanki (2004)

Using method describedby Nakariakov et al. (2001)we estimated magnetic field strength in the loop top to be equal 10-30 G

CONCLUSIONS

1. Interesting events happen in the Bastille Day (14 Jul).

2. Relatively strong flare was not associated with a CME due to failed eruption ofthe magnetic structure. Can be this a rule for old active regions with well developed, high-lying systems of loops?

3. The main agent of the deceleration was the magnetic tension of loops lying aboveerupting structure. Estimated magnetic field in the loop top is 10-30 G.

4. The second ever observation of radial oscillations of coronal loops was made. In this case we observed „the finger” that pulled loops – the magnetic structure ejected from below these loops.