ASTRO 3D ECR Astronomers in Australia Seminar Series
Simon Murphy, University of Sydney - A pre-main-sequence star that’s chemically peculiar due to its planet-forming disk
Dr Simon Murphy is an asteroseismologist, using stellar pulsations to probe stellar evolution, chemical peculiarities and to discover pulsation-timing binary systems.
Abstract:
The early evolution of a star is intertwined with that of its planets and protoplanetary disk. Recent results reveal that some stellar chemical peculiarities arise from separation of dust from gas in planet-forming disks. Thus stellar composition build-up is linked to planet formation and disk evolution, but many aspects of this remain unclear. Disk evolution is thought to be rapid (3—5 Myr timescales), but age estimates have previously relied upon the ages of stellar associations, which can be unreliable because of age dispersion within associations and episodic accretion. Hence, the ages and intrinsic metallicities of protoplanetary disks are rarely known precisely.
I will discuss recent results for the pre-main-sequence star HD139614, where we use stellar pulsations to determine an age to better than 10% precision. I will describe the evolution of pulsation frequencies in pre-main-sequence stars and how this allows masses and metallicities to be determined in a degeneracy-free way, permitting stellar associations to be dated with much better precision. Finally, I will explain how a planet-forming disk has resulted in this star being chemically peculiar.
ASTRO 3D is the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions. Our astronomers are searching to understand the evolution of the matter, light, and elements from the Big Bang to the present day. Check out our website for astronomy news, our research updates, and our education and outreach programs.
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