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Astronomy Colloquium
The Diverse Fates of Single and Binary Massive Stars
Date: Thursday, November 18th
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall
Speaker: Nathan Smith, University of Arizona
Abstract: Core-collapse supernovae (SNe) are bright, and therefore have the
potential to reveal details about the outcome of stellar evolution at large distances and different environments. However, our ability to theoretically predict which initial masses (and metallicities) produce which specific types of SNe they produce (e.g., Types Ib, Ic, II-P,II-L, IIn, IIb) is in rather miserable shape. This has critical implications for understanding the origin of long-duration GRBs, for example, which have been linked to Type Ic SNe. Observational input about the diverse end fates of massive stars helps this situation on two main fronts: 1. A growing number of direct detections of progenitor stars at the locations of SNe in archival pre-explosion data, mostly from HST, provides important links between the type of SN and the star's initial mass. 2. We now have reasonably good estimates about the relative fractions of different SN subtypes from the first decade of the Lick Observatory SN Search, allowing us to quantify what fraction of massive stars explode as which types of SN. Combining these two constraints, I will discuss the implications for the range of initial stellar masses that correspond to each type of SN. A key result (long suspected but now quantified) is that simple predictions of single-star stellar evolution models cannot be reconciled with the observed SN fractions, and that close binary evolution must be a primary agent responsible for SNe that have lost their H envelopes. Even accounting for this binary evolution (which has its own pitfalls), the remaining single-star progenitors contradict single-star evoution models, with some surprising implications. Time permitting, I will discuss some of the strange things that can occur in massive evolved binary systems -- especially one of them.
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