Show 1 -- photosphere & sunspots SUN COURSE - SLIDE SHOW 4 Show 2 -- corona & solar cycle Today: Sun today + waves + prominences +UFO’s Show 3 -- SOHO

Sun today from SoHO Photo sphere

Magnetic Field

Corona (2.0 MK)

LASCO C2

2. Waves on Sun - 4 exs (i) Waves in penumbra of sunspot

(ii) Wave from Flare In photosphere (MDI) (8-100 km/s 70 mins)

(iii) Solar Interior Guitar string can oscillate in different normal modes Sun too Recently SOHO discovered several million !! 3D Schematic

Sound waves -reflected at top/ refracted at bottom Use properties to infer structure interior Helioseismology - trapped in convection zone - different waves sense diff. regions i.e., wave turns !!

(iv) Possibly Important for Heating Corona to few MK 2 mechanisms: Reconnection or Waves Originally suggested sound waves - > generate by turbulence - propagate up - shocks But - not observed - magnetic regions hotter ?? Magnetic waves

From TRACE discovered waves after eruption

3. Prominences On disc in Halpha, see long, thin “filaments”  200 Mm x 6 Mm  Dark - cutting out light from below  Inside a.r. - small Outside - large (feet) At limb - 50 Mm i.e. in corona

On Disc

3D Structure

At Limb

Fine Structure -> transverse magnetic field inclined to axis Large Quiescent Prominence

Active Region Prominence --> Field along prominence --> Magnetic flux tube

In Eclipse

Properties  Immense, dense, cool vertical sheet of plasma in corona  Density m -3 (1000 corona)  Temperature 10, 000 K ( 0.01 corona)  Change slowly in shape --- long-lived (1-200 days)  Much fine structure  Reach down in series of “feet”  Lie along “polarity inversion line”  At some stage, may become unstable - ascend and disappear: An erupting prominence  Generally reform in same place

Polarity inversion line

Erupting Promin ence

Finally - Granpa