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Research Fellows Directory

Julian Pittard

Dr Julian Pittard

Research Fellow


University of Leeds

Research 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.

Interests and expertise (Subject groups)

Grants awarded

Astrophysical Flows: From Stellar Winds to Galactic Superwinds

Scheme: University Research Fellowship

Dates: Oct 2004 - Sep 2012

Value: £10,238,556.09