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Driven Supersonic Turbulence: Beyond Magnetic Flux Freezing

Project D-STurb
Research Area Astro Sciences
Principal Investigator(s) Dr Turlough Downes
Institution(s)
  • ICHEC, Galway, Ireland
  • Dublin City University, School of Mathematical Sciences, Dublin, Ireland

Abstract

Virtually all stars, including ones like our own sun, form in cold, dense clouds of gas and dust known as molecular clouds. These clouds are turbulent w ith the motions of the gas and dust in the cloud being observed to be supersonic. This turbulence influences the way in which stars condense under gravity from the molecular clouds it can stir up the cloud material and disrupt star formation or, perhaps counter- intuitively, it can create regions in a molecul ar cloud which actually encourage star formation. We know that magnetic fields are present in these molecular clouds, and also that they must have a signi ficant effect on the behaviour of the turbulence in the clouds. Until now most researchers have made the assumption that the magnetic field is perfectly t ied to the cloud material: if the cloud material moves it will drag the magnetic field with it and vice versa. This assumption is known as the "flux freezing approximation". However, magnetic fields only interact with charged particles in the cloud and so different physics is important for charg ed particles than that which is important for neutral particles: the molecular cloud behaves like a multifluid with each fluid (charged or neutral) obeying different physics and the flux freezing approximation is, as a result, rendered invalid.

In this project we will study the properties of turbulence in molecular clouds including the complex physics associated with magnetic fields and multifluid effects. We will study the types of structures produced by such turbulence with a view, ultimately, to understanding more about the evolution of molecular clouds and about how stars like our own sun form.

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