PhD ceremony Ms. Y. Chen: The X-Shooter spectral library and application to stellar population in galaxies

PhD ceremony: Ms. Y. Chen, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: The X-Shooter spectral library and application to stellar population in galaxies

Promotor(s): prof. S.C. Trager, prof. R.F. Peletier

Faculty: Mathematics and Natural Sciences

In this thesis we had a tour probing the evolutionary histories of stellar systems, namely star clusters and galaxies. The questions we addressed were the following: How old are these systems? What are their possible chemical compositions? What are the masses of the stars in galaxies? How did these galaxies and clusters form? To answer these questions, especially when galaxies or clusters cannot be resolved into single stars, stellar population models are required to decode the information hidden within the integrated light of those stellar systems.

We began with the ingredients of stellar population models. Stellar libraries are a key ingredient: we presented the new X-Shooter spectral library (XSL) and its unique features. This library is well suited to building stellar population models and also to kinematic investigation of stellar systems and to studying the physics of cool stars. XSL is also accompanied by our telluric spectral library, which will be useful to astronomers beyond simply performing telluric corrections for the XSL.

Next we presented new stellar population models based on XSL. We inspected the behavior of our models and described their application to stellar systems. We showed that by reproducing the integrated light of stellar systems with stellar population synthesis, one can know the age and metallicity of galaxies and star clusters. Finally, we showed that determining the dwarf-to-giant star ratio in distant galaxies is also possible!