[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster@admin.triumf.ca]

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Date/Time: Thu 2004-12-16 at 14:00

Location:  Auditorium          

Speaker:   Amanda Karakas (Dept. of Astronomy and Physics, St. Mary's Univ.)

Title:     Nucleosynthesis in Asymptotic Giant Branch Stars

Abstract: All low to intermediate mass stars pass through the Asymptotic Giant Branch (AGB) phase of stellar evolution. The AGB is the last nuclear-burning phase for these stars and is very short, comprising less than 1 per cent of the main-sequence lifetime. Nevertheless, it is on the AGB that the richest nucleosynthesis occurs. The nucleosynthesis is driven by thermal instability of the helium-burning shell, the products of which are mixed to the stellar surface by recurring mixing episodes. The AGB phase is terminated when rapid episodic mass loss expels the envelope into the interstellar medium. Thus stars are important contributors to the chemical evolution of stellar systems and galaxies.

I will review the AGB phase of evolution and the nucleosynthetic processes that occur in the diffent burning regions. I will discuss a couple of interesting examples including the production of 19F and the heavy Mg isotopes, and finish withh a brief look at some of the main uncertainties.

Stimulants available 15 minutes before the talk.

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