ASTR 3 Lecture Notes - Lecture 17: Inverse-Square Law, Proper Motion, Coronal Mass Ejection
Document Summary
Photons are carried to the surface by convection. Hot but not as hot as the layers around it. Expands far out, even lower density, but it is extremely hot. Surface of sun is 5800 k, but this is about 3 million k (not as hot as the core though). So we get an emission line spectrum: hot un-dense gas. Heat source of corona: magnetic field from solar activity. The sun is not merely a blackbody, with sunspots. Sunspots are dark because they are cooler than the surrounding gas. Magnetic (cid:28665)(cid:28668)(cid:28664)(cid:28671)(cid:28663) (cid:28668)(cid:28678) (cid:28675)(cid:28660)(cid:28677)(cid:28679)(cid:28668)(cid:28662)(cid:28680)(cid:28671)(cid:28660)(cid:28677)(cid:28671)y (cid:28668)(cid:28673)(cid:28679)(cid:28664)(cid:28673)(cid:28678)(cid:28664), (cid:28660)(cid:28673)(cid:28663) (cid:28678)(cid:28674)(cid:28672)(cid:28664)(cid:28679)(cid:28668)(cid:28672)(cid:28664)(cid:28678) (cid:28679)(cid:28667)(cid:28664)y"(cid:28677)(cid:28664) (cid:28675)(cid:28680)(cid:28678)(cid:28667)(cid:28664)(cid:28663) (cid:28674)(cid:28680)(cid:28679) (cid:28661)y (cid:28662)(cid:28674)(cid:28673)(cid:28681)(cid:28664)(cid:28662)(cid:28679)(cid:28668)(cid:28674)(cid:28673), (cid:28678)(cid:28667)(cid:28674)(cid:28681)(cid:28668)(cid:28673)(cid:28666) out the gas due to its pressure. As it expands away it cools off, so appears darker. There are always even number of sunspots that have opposite polarity. The number and polaris change around every 22 years. During which every 11 years the north and south poles flip.
