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Julian Pittard

Dr Julian Pittard

Dr Julian Pittard

Research Fellow

Interests and expertise (Subject groups)

Grants awarded

Astrophysical Flows: From Stellar Winds to Galactic Superwinds

Scheme: University Research Fellowship

Organisation: University of Leeds

Dates: Oct 2004-Sep 2012

Value: £10,238,556.09

Summary: Stars typically return a significant amount of their mass back into their surroundings during their lives and subsequent death throes. The expelled material, in the form of stellar winds, eruptions and explosions, sweeps up and compresses interstellar material, forming beautiful nebulae, and triggering new star formation. The most massive stars (up to 150 times as heavy as our Sun) have the greatest impact on their surroundings. Massive stars commonly occur in binary systems, where each star orbits the other. The collision of their powerful winds (which blow at speeds of up to 10 million mph) allows study not only of the stellar mass-loss rates, which is a key but rather uncertain parameter in models which examine the impact of these winds on the local galaxy, but also of the physics of high Mach number shocks and particle acceleration. I am conducting world-leading research in this area using theory and observations to advance our understanding. I am especially interested in using 3D hydrodynamical models to simulate synthetic data, which then aids the interpretation of observations. I have a particular interest in one of the most massive stars in our galaxy (Eta Carinae), which in 1843 suffered the greatest non-terminal stellar explosion known, and which in recent years has been recognized to be a binary system with a strong wind-wind collision. I am also constructing models of the particle acceleration which takes place at the strong shocks in these binaries. I am extending the above work to young clusters of massive stars to study how the winds and radiation fields clear out molecular material from the cluster. This will address crucial questions such as the efficiency of star formation and the impact of massive stars on the wider galaxy. It requires knowledge of how dense clouds of material react to impacting flows, and to this end I have been studying the interaction of clouds with shocks, shells and winds using a novel sub-grid turbulence model.

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