Our pages contain various quotes with which our editorial team does not always agree. Close this message to accept cookies or find out how to manage your cookie settings. Skip to main content Accessibility help We use cookies to distinguish you from other users and to provide you with a better experience on our websites. See also: Lambda Draconis, Fourth, Space station, Outflow channel, Beta Persei Dredge-Up in Asymptotic Giant Branch Stars - Volume 191. KäuflĪs main-sequence stars evolve on to the upper AGB, those of intermediate mass can carbon made by the triple-a process into their atmospheres, turning first into carbon-rich sstars and then into genuine carbon stars. Technetium and the third in AGB stars - II. In this way a carbon star is formed, very cool and strongly reddened stars showing strong carbon lines in their spectra. This is known as the second dredge up, and in some stars there may even be a third dredge up. Horizontal Branch - helium burning core - hydrogen burning shell.
As a result, the fusion products are mixed into the outer layers of the stellar atmosphere where they can appear in the spectrum of the star.įirst Dredge Up - expanding atmosphere cools star - stirs carbon, nitrogen and oxygen upward - star heats upĬore Helium Flash - continued compression with added helium ash ignites helium - lots of neutrinos Dredge Up: A dredge-up is a period in the evolution of a star where a surface convection zone extends down to the layers where the material has undergone nuclear fusion. and refined models, for example with regard to hot-bottom burning or the third dredge-up.
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