Stellar Libraries for population analysis




(Knowles, PhD thesis, 2019)

Theoretical star spectra

To understand galaxies we need to understand their stalight. Stellar populations in star clusters and galaxies retain information about the past history of how that population evolved with time, through the ages and element abundances of their stars.

One of the important building blocks for the analysis of light from stellar populations is the accuracy of the theoretical libraries of stellar spectra, vital to measure the element abundances in stars. To contribute such an extensive library we generated thousands of theoretical stellar spectra for modelling different abundance patterns of [alpha/Fe] and [C/Fe] in stars. See README file for a description of the theoretical grids available.

Empirical star spectra

Observed star spectra are important for understanding accurate fluxes from stars. One such empirical library is that of the MILES consortium. Other empirical star libraries are available, covering different wavebands, star types and spectral resolutions. For examples see SDSS surveys including the recent MaStar stellar library. Also see ESO surveys including the XShooter stellar library. More recently is the GAIA-ESO survey. Many older libraries are available from here.

Semi-Empirical star spectra

Above is an overlaid plot of semi-empirical star spectra generated by Adam Knowles, during his PhD at UCLan, showing spectra with atmospheric element abundance ratios of [α/Fe]=-0.2, for a wide range of effective temperatures and metallicities. These spectra are based on combining empirical MILES star spectra with adjustments from ratios of our theoretical star spectra, to convey MILES stars, but with different element abundance ratios. See Knowles et al. 2021 for details.