1. Helio-seismology in 20min Introduction Solar Structure Physics Involved Observing Networks Observing Networks Current Results Summary David Brands Stafford and District Astro. Soc Stafford and District Astro. Soc.

2. What is Helio-Seismology? “Helios” of the sun (all Greek)“Helios” of the sun (all Greek) “Seismos” earthquake“Seismos” earthquake “Logos” knowledge“Logos” knowledge Mis-labled because there is almost no shear activity (s wave), only p waves (like sound)Mis-labled because there is almost no shear activity (s wave), only p waves (like sound) “Study of solar p waves to determine structure and activity of the sun.”“Study of solar p waves to determine structure and activity of the sun.”

3. Earthquake Propogation P wavesP waves –Pressure –Fast S wavesS waves –Shear –Slow

4. Particle displacement parallel to wave directionParticle displacement parallel to wave direction The particles do not move with the wave; simply oscillate back and forthThe particles do not move with the wave; simply oscillate back and forth Wave is seen as the motion of the compressed region (ie, a pressure wave)Wave is seen as the motion of the compressed region (ie, a pressure wave) Pressure “P” Longitudinal wave

5. Particle displacement perpendicular to wave directionParticle displacement perpendicular to wave direction Particles do not move with the wave; they simply oscillate up and down Particles do not move with the wave; they simply oscillate up and down Wave is seen as the motion of the crests and troughsWave is seen as the motion of the crests and troughs Shear “S” Transverse wave

6. Water Waves Example of waves that involve a combination of both longitudinal and transverse motions.Example of waves that involve a combination of both longitudinal and transverse motions. Particles travel in clockwise circles. The radius of the circles decreases as the depth into the water increases.Particles travel in clockwise circles. The radius of the circles decreases as the depth into the water increases. See two particles in blue to show that each particle travels in a clockwise circle as the wave passes.See two particles in blue to show that each particle travels in a clockwise circle as the wave passes.

7. Rayleigh surface waves In a solidIn a solid Elliptical pathsElliptical paths Rayleigh waves different from water waves in one important way.Rayleigh waves different from water waves in one important way. Water wave all particles travel in clockwise circles, but in Raleigh solids:Water wave all particles travel in clockwise circles, but in Raleigh solids: Surface particles counter-clockwise ellipseSurface particles counter-clockwise ellipse Particles at depth clockwise ellispes.Particles at depth clockwise ellispes.

8. Helioseismology Sun – almost no “s” waves, mainly “p”Sun – almost no “s” waves, mainly “p” Disturbances generated in convection zone, near photosphere surfaceDisturbances generated in convection zone, near photosphere surface Propagate to surfacePropagate to surface Study of surface effects reveals interiorStudy of surface effects reveals interior Resonances make the sun “ring” like a bellResonances make the sun “ring” like a bell

9. Internal Structure of Sun ProvenByHelioSeizmology 2.2M Deg C 170K km 500K km 1.6% 170000 Yr 10 Days 50Km 5mins/0.003 Hz 15.6M Deg C 700K km 5000 Deg C 9000 Deg C 2.2M Deg C 0.5 MY

10. Solar Flare causing Quake

11. Mathematical models of oscillations Mirage – light bent by hot airMirage – light bent by hot air Actually hotter air easier / faster path Sound bent in resonance cavities,Sound bent in resonance cavities, Temp gradients, adiabatic regions N no. nodes radially outward M no. nodes around the equator L no. nodes around the azimuth L 20 M 17 IN OUT

12. Vibration Nodes Example 1st Harm 2nd harm 3rd Harm 4th Harm

13. Mathematical models of oscillations Mirage – light bent by hot airMirage – light bent by hot air Actually hotter air easier / faster path Sound bent in resonance cavities,Sound bent in resonance cavities, Temp gradients, adiabatic regions N no. nodes radially outward M no. nodes around the equator L no. nodes around the azimuth L 20 M 17 IN OUT

14. Sounds of the sun Wideband filterWideband filterWideband filterWideband filter All sounds speeded up 42,000 times to become audibleAll sounds speeded up 42,000 times to become audible 0.003 Hz0.003 Hz Human detection starts at 25HzHuman detection starts at 25Hz

15. Bison Network ( Birmingham Solar Oscillations Network) Six-station network – Resonant Scattering Spectrometers

16. Gong Network Global Oscillation Network GroupGlobal Oscillation Network Group Similar to BisonSimilar to Bison GONG is:GONG is: – a six-station network – extremely sensitive velocity imagers – located around the Earth – obtain nearly continuous observations of the Sun's oscillations.

17. Gong Instruments (1994) InterferometerInterferometer 6 unit trial6 unit trial Before shippingBefore shipping

18. Data: Schematic Movie Data: Schematic Movie

19. Gong Far Side Mapping P wave mappingP wave mapping Uses interior modelUses interior model

20. Network Results Global results:Global results: –Confirmed / improved model of sun interior –Eliminated model errors in “missing nuetrino” –Maps activity and sunspots on “far” side –Found “jet stream” in convection layers –Calculated sun age – agrees with meteorites

21. Helio-Seismology Conclusions:Conclusions: –P wave analysis, some S wave, good models –global detector networks –Internal structure revealed / refined –“see” spots and activity on far side –Now looking at nearby stars for similar insight

22. Helio-seismology in 20 Minutes Questions? David Brands Stafford and District Astro. Soc Stafford and District Astro. Soc.