The modification by diffuse radiation of "cometary tail" formation behind globules

¹ Physics Department, University of Crete, 714 09 Heraklion, Crete, Greece
² Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
³ Department of Physics and Astronomy, University of Cardiff, PO Box 913, Cardiff CF24 3YB, UK
⁴ Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, UK

Corresponding author: K. G. Pavlakis,Robin.Williams@astro.cf.ac.uk

Received: 9 October 2000
Accepted: 4 January 2001

Abstract

We study the evolution of a globule of neutral material immersed in the more tenuous hotter plasma of an H ii region surrounding newly born OB stars. The neutral globule is illuminated by the direct ionizing radiation of OB stars, and by diffuse radiation emitted by recombination in the surrounding ionized gas. We perform 2D, time dependent axisymmetric hydrodynamic simulations, and find that, for values of the diffuse field of the order of 10% of the direct field, the evolution of the globule is completely different to its evolution when the diffuse field is neglected.