A new radiative cooling curve based on an up-to-date plasma emission code^*

¹ Astronomical Institute, University of Utrecht, Postbus 80000, 3508 TA Utrecht, The Netherlands e-mail: K.M.Schure@phys.uu.nl
² SRON, Utrecht, The Netherlands
³ Centre for Plasma Astrophysics, K.U. Leuven, Belgium
⁴ FOM-Institute for Plasma Physics “Rijnhuizen”, Nieuwegein, The Netherlands

Received: 14 May 2009
Accepted: 24 September 2009

Abstract

This work presents a new plasma cooling curve that is calculated using the SPEX package. We compare our cooling rates to those in previous works, and implement the new cooling function in the grid-adaptive framework “AMRVAC”. Contributions to the cooling rate by the individual elements are given, to allow for the creation of cooling curves tailored to specific abundance requirements. In some situations, it is important to be able to include radiative losses in the hydrodynamics. The enhanced compression ratio can trigger instabilities (such as the Vishniac thin-shell instability) that would otherwise be absent. For gas with temperatures below 10⁴ K, the cooling time becomes very long and does not affect the gas on the timescales that are generally of interest for hydrodynamical simulations of circumstellar plasmas. However, above this temperature, a significant fraction of the elements is ionised, and the cooling rate increases by a factor 1000 relative to lower temperature plasmas.