1. ASYMMETRY IN TEMPERATURE OF SOLAR POLES SOLAR PHYSICS January 18th, 2013 Pilar Herrero Sinovas SOLAR PHYSICS January 18th, 2013 Pilar Herrero Sinovas

2. Introduction: How was the asymmmetry discovered?

3. Ulysses:Trajectory  The ESA-NASA Ulysses robotic probe was launched in October 1990.  Jupiter would accelerate Ulysses out of the ecliptic plane to high latitudes.  The ESA-NASA Ulysses robotic probe was launched in October 1990.  Jupiter would accelerate Ulysses out of the ecliptic plane to high latitudes.

4. Ulysses:Overflying the Poles Three times overflew the solar poles:  1994-1995 Solar minimum  2000-2001 Solar maximum  2007-2008 Solar minimum Three times overflew the solar poles:  1994-1995 Solar minimum  2000-2001 Solar maximum  2007-2008 Solar minimum

5. Ulysses: SWICS The Solar Wind Ion Composition Spectrometer (SWICS): - Temperatures - Mean speeds of solar-wind ions The Solar Wind Ion Composition Spectrometer (SWICS): - Temperatures - Mean speeds of solar-wind ions

6. Ulysses: SWICS  First orbit: SWICS measured the ratio O7+/O6+  Lower in the North Pole Continuity equation: n, u: densidad y velocidad R: Tasa de recombinación C: Tasa de ionización Lower T in North Pole!  First orbit: SWICS measured the ratio O7+/O6+  Lower in the North Pole Continuity equation: n, u: densidad y velocidad R: Tasa de recombinación C: Tasa de ionización Lower T in North Pole!

7. SWICS: Results  Average temperature of the Sun's polar wind is about one million degrees C.  But over North Pole the wind is about 44.000 degrees cooler than over South!  Average temperature of the Sun's polar wind is about one million degrees C.  But over North Pole the wind is about 44.000 degrees cooler than over South!

8. Magnetic Field  The "cool spot" follows the north magnetic pole when the sun's poles flip.

9. What are the causes? UNKNOWN!  But related asymmetries have been studied for Polar Coronal Holes (PCH): - Area - Magnetic Flux Density - Wind Speed - Expansion Factor UNKNOWN!  But related asymmetries have been studied for Polar Coronal Holes (PCH): - Area - Magnetic Flux Density - Wind Speed - Expansion Factor

10. What are the causes?  All data from first flight over the poles (minimum)

11. Asymmetry in Area  1996 large polar coronal holes extend to or below 50º  North larger than the South: N = 8% S = 7%  1996 large polar coronal holes extend to or below 50º  North larger than the South: N = 8% S = 7%

12. Asymmetry in Area Different Areas! North Larger Different Areas! North Larger

13. Asymmetry in magnetic flux densities North: Magnetic Flux Density Twice lower! North: Magnetic Flux Density Twice lower!

14. Expansion Factor and Velocity Expansion factor: Compares the magnitude of the photospheric magnetic field at the footpoint of the tube with its magnitude at 2.5 solar radii. North:  Higher velocity: 15-20 km/s  Lower expansion factor: 5% Expansion factor: Compares the magnitude of the photospheric magnetic field at the footpoint of the tube with its magnitude at 2.5 solar radii. North:  Higher velocity: 15-20 km/s  Lower expansion factor: 5%

15. Summary North Pole: Lower: - Temperature - Magnetic Flux - Expansion Factor Higher: - Area - Velocity North Pole: Lower: - Temperature - Magnetic Flux - Expansion Factor Higher: - Area - Velocity But no definitive answer exists!! But no definitive answer exists!!