sampleess 471/503Research paper titles

Transcription

1 Research Papers Any subject arguably important in Space Physics (Important: clear it with Bob first) Not new research, but synthesis of published research about a topic Pose a question, and provide the best answer so far from the literature THIS IS NOT A BOOK REPORT ~10 pages + figures and references 50% of your grade

2 sampleess 471/503Research paper titles The Termination Shock: New Data, Questions, and Getting There in Less Than Twenty-Eight Years Stellar wind conditions of extrasolar planetary systems What Causes the Theta Aurora? Ionospheric Scintillation: Modeling the Effects on GPS Receivers The Anomalous Slowing of the Pioneer 10 Spacecraft and the Possible Implications on the Field of Space Physics Resistivity at the Magnetotail Reconnection Site Heating of the Solar Corona Why does the solar equator rotate faster than the poles? Collisionless Shocks On Auroral Emissions at the Foot of the IFT at Jupiter

3 Today: Solar Magnetic Fields Frozen in condition Babcock s theory (Still working on Chapter 3 of K&R) But first, a few more comments about Solar Seismology

4 First a little more about solar seismology modal structure

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7 g-waves not confirmed p-waves basis for solar seismology

8 Standard Model problems/changes Missing Solar Neutrinos (now considered solved) Light element abundance too low (Li, Be, B) affects Convection Zone depth Chemical controversy at the solar photosphere ( ) 160 minute oscillations g-modes controversal Not Included in model: B-fields in Core Core rotation Note also new Neutrino detector at South Pole called IceCube and

9 Equator rotates faster Ω = A + B sin 2 φ + C sin 4 φ φ is solar latitude A=13.76 B= C=-2.19 o /day ~30% slower at poles than equator Differential Rotation Note, determining solar rotation using sunspots is skewed a little fast because weighted by motions near equator

10 Magnetic fields in the sun Sunspot observations Hale observations First: learn about Frozen in condition (solar plasmas drag B-field around) Babcock Heuristic theory for the 22 yr cycle

11 Butterfly diagram (sunspots)

12 Hale Observations in 1909 Studies solar B-field using Zeeman Effect 1. B always present in sunspots 2. B ~ 200 G to 4000 G 3. Most sunspots bi-polar (84%) 4. When found sinngly, almost always in region of opposite polarity 5. Bi-polar sunspots tilted: Preceeding (p) sunspot always closer to equator than following (f) (typically 5-6 o at o lat ) 6. Polarity Law for 11 yrs 7. (p) = + and (f) =- North Hemisphere and reversed in South Pattern exactly reverses every solar cycle

13 Subsequent B-field data 1. Beginning of new solar cycle starts at high latitudes (40 o ) and overlaps with previous cycle 2. B-fields also exist outside sunspots B~ 0.1 to 100 G 3. Polar field weak ~1 G centered on pole, reverses with cycle (>55 o lat) 4. Large Poloidal fields (one pole reverses, then 1 year later, the other) 5. Appearance of new B-field flux associated with active regions (sunspots dark because B-inhibits convection) 6. Transport and mixing of solar B-fields

14 Basic EM theory (background to frozen in condition) Faraday s Law Or emf Changing Bfield induces a current which OPPOSES changing Bfield Example: sics/lenz's.html

15 Basic EM theory (background to frozen in condition) Faraday s Law Or emf Changing Bfield induces a current which OPPOSES changing Bfield Example: sics/lenzs.html

16 Relativistic Transformation Modified Ohms Law Changing magnetic field given by two terms

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18 Frozen in Condition Plasma and B-field move together Another way to think of this is by transforming the E field into the moving frame so Ohms Law is Dominated by vxb term Which just becomes the frozen in condition for large σ

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21 Babcock Theory summary: 1. Differential solar rotation winds up the B-field 2. Flux ropes become buoyant, and pop up (stops B-field growth) 3. Sunspots migrate/diffuse annihilating more equatorward (preceding) spots, and changing polar polarity from with following spots 4. This changes poloidal field and winding adds opposite polarity B (unwinds) For more modern theory on solar dynamo see Nice lecture at

22 Mean solar Longitudinal velocity

23 Photosphere, Chromosphere, Corona

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