Cameron Bell (AIP)

A revised age scale for young Galactic clusters
When Dec 08, 2016 from 02:30 PM to 03:30 PM
What
  • Colloquium
Where SH Lecture Hall
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The formation and evolution of low-mass stars and planets is one of the fundamental goals of modern astronomy, however our understanding hinges upon the ability to assign precise and reliable ages to young stars. Unfortunately, the age of a star is not a directly measurable property and thus the ages of all young stars are "to varying degrees" model-dependent, and it is this dependency which can result in uncertainties of up to 100% depending on which age-dating technique one adopts and over which mass range it is applied.

In this talk I will give a brief overview of several methods of age-dating young stars, however I will place a large emphasis on the most common of these; namely the use of model isochrones. I will discuss the underlying issues with these methods before introducing a set of semi-empirical model isochrones incorporating an empirical colour-Teff relation and bolometric corrections based on the observed colours of Pleiades members, with theoretical corrections for the dependence on log g. Using these models I will present a revised age scale for young Galactic clusters and associations in the Solar Neighbourhood for which the pre-main-sequence contraction and main-sequence turn-off and lithium depletion boundary ages agree. This revised age scale implies that the canonical ages for young (< 15 Myr) clusters are likely too young by a factor of two; a result with wide-ranging implications.