The importance of binary systems for stellar population studies of early-type galaxies
Final Report Abstract
Many stars are born as binary systems, orbiting each other periodically. However, the binary components are not seen separately by a distant observer who tries to analyse the population of stars in a galaxy. Such an analysis relies on models that synthesize the combined light from stars belonging to one or more generations: so-called population synthesis models. Due to the complex computational tasks involved, and partly due to previous lack of knowledge, most available population synthesis models are based on single stars, not taking into account binaries. As a first step towards analysing the stellar populations of elliptical galaxies with new models, we developed a procedure to estimate the ages of stars and their heavy element abundance, based on the observed colours of these galaxies. We found that not all of the commonly used models are able to adequately reproduce the galaxy colours of the nearby universe. This allows in the next step to apply the newly developed binary models by Z. Li and coworkers to the elliptical galaxies' colours, and test whether the resulting information that we obtain differs from the single-star case.
Publications
- 2012, MNRAS 427, 2376: "Observed versus modelled u-, g-, r-, i-, z-band photometry of local galaxies - evaluation of model performance"
Hansson, Lisker & Grebel
(See online at https://doi.org/10.1111/j.1365-2966.2012.21659.x)
