Honours astronomy: CSM II
Circumstellar matter II
  Prof. G. Woan and Dr A. Russell , room 312 Kelvin Building
10 lectures starting 11 January 2012

This course continues the themes of  CSM I, showing how the ideas of stellar atmospheres can be extended to deal with stellar winds.  We investigate the dynamics and structure of the solar photosphere, corona, transition region and corona and show how mass-loss is a consiquence of coronal overpressure. We study stellar winds driven by both pressure and radiations, investigating mass-loss rates and the observational evidence for line driven winds.  Finally, we return to  the solar wind and examine how the solar magnetic field modulates its structure and dynamics.  We also investige the geomagnetic effects of the solar wind.


 

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Course details
Copies of lecture notes will appear here as the course proceeds. They are for reference only, and should not be used to replace your own lecture notes. You will find the course much harder if you don't create your own written version, so please do not print these notes out in quantity.

Solar atmospheric structure
 Why does the solar disc have a sharp edge?;  Isothermal atmospheres in hydrostatic equilibrium and scale height; opacity and limb darkening; chromospheric emission lines; the transition region and the corona;coronal heating -- acoustic and Alfvenic waves; radiative instability; width of the transition region and Spitzer conductivity
lecture notes:  1 2 3 4 5 6 7 8 9 10 11 12 13 14
Pictures: [  Sun in H-alpha | Sun in UV | The solar corona  ]
Handouts:[ misc diagrams  |  The solar atmosphere  ]

Static or dynamic equilibrium?
Conditions for a hydrostatic corona; isothermal, static atmosphere;  the Chapman model; wind theories; the solar wind as coronal expansion; isothermal winds; the Parker wind model; velocity profiles and the critical solution; stellar breeze solution; ram pressure; mass-loss rate
lecture notes:  15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
Pictures: [  Hale-Bopp | solar wind measurements  | the real solar wind (movie)]
Handouts:[ Parker model ]

Radiatively driven winds
opticall thin solutions;Eddington luminosity Castor, Abbott, Klein velocity profiles; accretion solutions; mass-loss rates; wind luminosity; effect of finite stellar size on radiation pressure; non-grey atmospheres; line-drive winds; P Cygni profiles - theory and interpretation; multiple scattering, conservation of energy and momentum; performance factor; pulsation and magnetically driven winds; magnetically rotating winds
lecture notes: 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
Pictures: [ blinking eye nebula | Eta Carinae | P-Cygni profile ]

The solar wind
magnetic fields and flux freezing; magnetic pressure; plasma beta; stream structure and the ballerina model; the current sheet; Archimedian  (Parker) spirals; coronal holes; high and low speed streams; transients; the solar cycle; geomegnetic effects
lecture notes: 50 51 52 53 54 55 56 57
Handout : [ the solar wind ]

Question Sheet [pdf version ]

Solution Sheet [pdf version ]

Recommended Book:
Introduction to stellar winds ; Henny J.G.L.M. Lamers and Joe Cassinelli (Cambridge University Press, 1999)
Note that this is an advanced text, aimed at graduate astronomy students, but it contains much of the material in the course.