One of the great problems of astrophysics is the unanswered question about the origin and mechanism of chromospheric and coronal heating. Just how these outer stellar envelopes are heated is of fundamental importance, since all stars have hot chromospheric and coronal shells where the temperature rises to millions of degrees, comparable to the temperatures in the stars' cores. Here for the first time is a comprehensive inventory of the proposed chromospheric and coronal heating theories. The proposed heating processes are critically compared, and the observational evidence for the various mechanisms is reviewed. This is essential reading for all those working in such fields as stellar activity, radio and XUV emission, rotation, and mass loss, for whom a detailed and consistent presentation of our knowledge of chromospheric and coronal heating mechanisms is urgently needed.

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 Physical Research Laboratory Bangalore560034,India P. O. Box No. 198 hasan@iiap. ernet. in Udaipur313001,India ambastha@prl. ernet. in P. K. Manoharan Radio Astronomy Centre H. M. Antia Tata Institute Tata Institute of Fundamental Research of Fundamental Research P. O. Box 8 Homi Bhabha Road Udhagamandalam (Ooty) 643001, Mumbai400005,India India antia@tifr. res. in mano@racooty. ernet. in ArvindBhatnagar Udaipur Solar Observatory P. Ulmschneider Physical Research Laboratory Institut fur 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 Physical Research Laboratory Bangalore560034,India P. O. Box No. 198 hasan@iiap. ernet. in Udaipur313001,India ambastha@prl. ernet. in P. K. Manoharan Radio Astronomy Centre H. M. Antia Tata Institute Tata Institute of Fundamental Research of Fundamental Research P. O. Box 8 Homi Bhabha Road Udhagamandalam (Ooty) 643001, Mumbai400005,India India antia@tifr. res. in mano@racooty. ernet. in ArvindBhatnagar Udaipur Solar Observatory P. Ulmschneider Physical Research Laboratory Institut fur .. Theoretische Astrophysik P. O. Box No. 198 Univ. Heidelberg Udaipur313001,India Tiergartenstr. 15 arvind@prl. ernet. in 69121Heidelberg,Germany ulm@ita. uni-heidelberg. de S. M. Chitre Department of Physics University of Mumbai P. Venkatakrishnan Mumbai400098,India Udaipur Solar Observatory kumarchitre@hotmail. com Physical Research Laboratory P. O. Box No. 198 BholaN. Dwivedi Udaipur313001,India Department of Applied Physics pvk@prl. ernet. in Institute of Technology Banaras Hindu University Varanasi221005,India dwivedi@banaras. ernet. in TableofContents OverviewofSolarPhysics S. M. Chitre...1 1 Introduction...1 2 CompositionandStructureoftheSun...3 2. 1 EquationsofStellarStructure...4 2. 2 TheStandardSolarModel...7 3 ProbesoftheSun'sInterior...10 3. 1 SolarNeutrinoProblem...

This book examines the origins, development and fate of intelligent species in the observable part of our universe. It scrutinizes what kind of information about extraterrestrial intelligent life can be inferred from our own biological, cultural and scientific evolution and the likely future of mankind. There is emphasis on the geological conditions and consequences of life's conquest of land as the pre-condition for the emergence of life with our type of technical intelligence.

This book examines the origins, development and fate of intelligent species in the observable part of our universe. It scrutinizes what kind of information about extraterrestrial intelligent life can be inferred from our own biological, cultural and scientific evolution and the likely future of mankind. There is emphasis on the geological conditions and consequences of life's conquest of land as the pre-condition for the emergence of life with our type of technical intelligence.

This volume has grown out of lectures addressing primarily graduate students and researchers working in related areas in both astrophysics and space sciences. All contributions are self-contained and do not require prior in-depth knowledge of solar physics. The result is a unique textbook that fulfills the needs of those wishing to have a pedagogic exposition of solar physics bringing them up-to-date in a field full of vitality and with exciting research.

Peter Ulmschneider zeichnet anhand von 10 Entwicklungsstufen den Weg von der Entstehung des Universums bis zum modernen Menschen. Unser Universum ist im Urknall als ein mit Materie gefullter, sich unaufhoerlich ausdehnender Raum entstanden, in dem die Naturgesetze immer komplexere Strukturen schufen: chemische Elemente, Sterne, Galaxien, Planeten, und schliesslich den Menschen mit seinem Gehirn als Sitz der Intelligenz. Diese Entwicklung durfte sich weiter fortsetzen und nach ihrem Zenit wieder mit dem Zerfall aller Strukturen enden, um einem stetig dunner werdenden, nur noch von Photonen und Neutrinos bevoelkerten Weltall Platz zu machen.