Red giant and supergiant stars have long been favorites of professional 6 and amateur astronomers. These enormous stars emit up to 10 times more energy than the Sun and, so, are easy to study. Some of them, specifically the pulsating long-period variables, significantly change their size, brightness, and color within about a year, a time scale of interest to a single human being. Some aspects of the study of red giant stars are similar to the study of pre-main-sequence stars. For example, optical astronomy gives us a tantalizing glimpse of star forming regions but to really investi gate young stars and protostars requires infrared and radio astronomy. The same is true of post-main-sequence stars that are losing mass. Optical astronomers can measure the atomic component of winds from red giant stars that are undergoing mass loss at modest rates 6 (M $ 10- M9/yr.). But to see dust grains and molecules properly, 5 especially in stars with truly large mass loss rates, ~ 10- M9/yr, one requires IR and radio astronomy. As this stage of copious mass loss only lasts for ~105 years one might be tempted to ask, "who cares?".
Hvis denne bog ikke er noget for dig, kan du benytte kategorierne nedenfor til at finde andre titler. Klik på en kategori for at se lignende bøger.