SOLAR FLARES

Marina Rodríguez Baras1

Solar activity

Why do we study it?

• Close study of the internal processes of a star.

• Preventing the effects on the Earth.

NASA/Steele Hill

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Solar flare: definition

Definition: Big explosions on the surface of the sun.

Effect: They heat material and release energy.

Place: Usually near sunspots.

TRACE satellite. September 5, 20053

Example: 13 Dec 2006 (Hinode)

Hinode's Solar Optical Telescope (SOT) on Dec. 13, 2006 4

Energy released

• Electromagnetic radiation: Across the whole spectrum.

• Flares classified by their X-ray flux. Each class has a tenth of the energy of the superior one.

Class Peak flux [w/m2] in 1-8 Å

X >10-4

M 10-5 to 10-4

C 10-6 to 10-5

B 10-7 to 10-6

A 10-8 to 10-7

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Energy released

Each category has nine subdivisions (X1-X9, M1-M9…)

NOAA satellites, July 2000

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Origin: magnetic shear

• Origin in the structure of the magnetic field around sunspots.

• Magnetic field lines twisted and sheared. • Reconnection of lines provoke release of

energy.

NOAA Active Region AR6659, June 10, 1991 7

Origin: magnetic shear

Hinode's Solar Optical Telescope (SOT), 10th-14th December 2006

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Reconnection of lines

• Tension accumulated causes a reconnection of the lines of magnetic field.

• The reconnection implies releasing a high amount of energy.

Figure of Gordon D. Holman (NASA) 9

Reconnection of linesMagnetic reconnection Reconnection in 3D

Figures of Gordon D. Holman (NASA) 10

Global events

K Schrijver & A (NASA) (solar flare 1st August 2010) 11

Global events

Solar Dynamics Observatory (1st August 2010) 12

It is waiting for us!

Thank you!13

14Solar Dynamics Observatory (NASA), April 19 2010