2002/06/30 by Manuel Güdel, Manuel Guedel · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #History and Developments in Astronomy #Ionization #Main sequence #Molecular cloud #Protostar #Red giant #Solar and Space Plasma Dynamics #Stars #Synchrotron radiation #Young stellar object #astro-ph
paper · pdf · doi:10.1146/annurev.astro.40.060401.093806
published as Ann.Rev.Astron.Astrophys. 40 (2002) 217-261 · to be published in Annual Review of Astronomy and Astrophysics, Vol. 40:217-261 (2002). Higher-resolution figures are available at http://www.astro.phys.ethz.ch/papers/guedel/guedel_p_nf.html
arxiv created 2002/07/03 · openalex publication_date 2002/09/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
▪ Abstract Radio astronomy has provided evidence for the presence of ionized atmospheres around almost all classes of nondegenerate stars. Magnetically confined coronae dominate in the cool half of the Hertzsprung-Russell diagram. Their radio emission is predominantly of nonthermal origin and has been identified as gyrosynchrotron radiation from mildly relativistic electrons, apart from some coherent emission mechanisms. Ionized winds are found in hot stars and in red giants. They are detected through their thermal, optically thick radiation, but synchrotron emission has been found in many systems as well. The latter is emitted presumably by shock-accelerated electrons in weak magnetic fields in the outer wind regions. Radio emission is also frequently detected in pre–main sequence stars and protostars and has recently been discovered in brown dwarfs. This review summarizes the radio view of the atmospheres of nondegenerate stars, focusing on energy release physics in cool coronal stars, wind phenomenology in hot stars and cool giants, and emission observed from young and forming stars. Eines habe ich in einem langen Leben gelernt, nämlich, dass unsere ganze Wissenschaft, an den Dingen gemessen, von kindlicher Primitivität ist—und doch ist es das Köstlichste, was wir haben. One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike—and yet it is the most precious thing we have. A. Einstein 1951, in a letter to H. Mühsam, Einstein Archive 36-610