Lectures on Solar Physics

TheideafortheselectureseriesaroseataWorkshoponsolarphysicswhichwas heldattheInterUniversityCentreforAstronomyandAstrophysics(IUCAA), Pune/IndiainDecember2000. ThisWorkshopaimedtopresentacompreh- siveandup-to-dateoverviewofsolarphysicsforinterestedstudentsandfaculty inotherbranchesofastrophysics. Itwasintendedtoshowthatthis?eld, c- centratingonourcloseststar, isavitalandexciting?eldofresearch. Forthis purposeanumberofcomprehensivereviewswereorganisedwhichassumedthat theaudiencewouldhaveonlyabasicphysicsbackgroundbuthadnoprior knowledgeaboutsolarphysics. Thesetoflecturescoveredtopicsrangingfrom thesolarcoretotheconvectionzone, thephotosphere, chromosphere, andcorona andextendingtothesolarwindintheinterplanetarymedium DuringandaftertheWorkshoptherewasmuchenthusiasmforthisform ofpresentationanditwasfeltthattheselectures, augmentedbyincludingthe latestresearch?ndingsinthe?eld, wouldbebene?cialtoamuchlargeraudience. Thustheplanforthisbookoriginatedwhichcouldthenberealisedthanksto thepublishers, Springer-Verlag. Thereare9articlesbasedonthelecturesgivenattheWorkshop. Thearticle byChitreon"OverviewofSolarPhysics"givesanintroductiontothewhole varietyofphenomenaofsolarphysics, theproblemsandtheirsolutionsand salientresults. Thearticleon"InstrumentationandObservationaltechniques relatedtoSolarPhysics"byBhatnagardescribesindetailtheprinciplesof- larinstrumentationnormallyusedtotakesimplewhitelight, monochromatic andspectroscopicobservations. Practicalmethodstomeasureimportantbasic parameters, likearea, positionandtheclassi?cationofsunspotsaredescribed indetail. Antia'sarticleon"SolarInteriorandSeismology"describesthesolar interior, thetechniqueofhelioseismologyandhowthisnewtechniqueallowsa determinationoftheinternalstructureanddynamicsoftheSunandconstrains theoriesofstellarstructure, evolutionandangularmomentumtransport. - bastha'sarticleon"TheActiveandExplosiveSun"givesanoverviewofhighly time-dependentphenomenainthephotosphere, chromosphereandcoronaofthe Sunandprovidessometheoreticalmodelsofthesolar?ares. Hasan'sarticle on"MagneticFluxTubesandActivityontheSun"discussesthegeneration, storageandemergenceofmagnetic?eldsintheformofsmall-scale?uxtubes andexaminestheirroleinheatingofthechromosphere. Ventakrishan'sar- cleon"SolarMagneticFields"givesatheoreticaloverviewofthegeneration VI Preface ofmagnetic?eldsbythedynamomechanism, thegeneralmagnetic?eldtop- ogyandhowthemagnetic?eldsaremeasured. Ulmschneider'scontributionon "ThePhysicsofChromospheresandCoronae"discusseswhyallstarslikethe Sunhavehotouterchromosphericandcoronallayers. Itidenti?estheheating mechanismsanddynamicalprocesseswhichtakeplacebothinthepresenceand absenceofmagnetic?elds. ThearticlebyDwivedion"TheSolarCorona"gives ageneraloverviewofthesolarcorona, howitisobservedandwhatthephy- calprocessesleadingtoitsformationare. FinallyManoharan'scontributionon "TheSolarWind"describesthegenerationandmeasurementofthesolarwind derivedfrominsituobservationsbyspacecraftandinterplanetaryscintillation studies. Wehopethatbyreadingtheselectures, interestedpeople, amateurs, graduate andpostgraduatestudentswillbemotivatedtotakeupsolarphysicsasanarea ofresearch, andshareourexcitementaboutthewondersofourneareststar- theSun. WearethankfultoT. PadmanabhanandtheInterUniversityCentrefor AstronomyandAstrophysics, PunefororganisingandhostingthisWorkshop onSolarPhysics. Mumbai, Udaipur, Heidelberg H. M. Antia February2003 A. Bhatnagar P. Ulmschneider ListofContributors AshokAmbastha S. S. Hasan Udaipur Solar Observatory Indian Institute of Astrophysics Physica