Urtzi Jauregi

Univerza v Ljubljani, Fakultet za matematiko in fiziko

torek, 21. 4. 2009, ob 15h v F3

In the age of large automated spectroscopic surveys such as RAVE and GAIA, synthetic spectra are an essential tool for the task of determining stellar parameters –such as effective temperature, gravity, chemical composition, and rotation velocity– for a very large sample of objects. It is therefore crucial to have as good spectrum synthesis methods as possible, and to understand the many quirks and pitfalls researchers face when working with them.

Although the future of the field clearly lies in full 3D hydrodynamic atmosphere models –which start from very basic principles to use as few free parameter as possible– it seems that long computation times will make their generalized use for research impractical in the next 5-10 years. Currently, the emphasis is on classical 1D stationary models with varying degrees of sophistication.

I will briefly describe some of the current most important spectrum synthesis methods, describing their relative advantages in terms of physical complexity of the underlying models, computation time, and public availability of the code –an essential, but often overlooked consideration in scientific research. I will also describe in some detail one of the de facto standards in the field, the Kurucz family of spectrum synthesis programs, to give an idea of a typical spectrum synthesis procedure.