GalevNB: A conversion from N-body simulations to observations

We present GalevNB (Galev for N-body simulations), a utility that converts fundamental stellar properties of N-body simulations into observational properties using the GALEV (GAlaxy EVolutionary synthesis models) package, and allowing direct comparisons between observations and N-body simulations. It works by converting fundamental stellar properties, such as stellar mass, temperature, luminosity and metallicity into observational magnitudes for a variety of filters used by mainstream instruments/telescopes, such as HST, ESO, SDSS, 2MASS, etc., and into spectra that span the range from far-UV (90 Å) to near-IR (160 μm). As an application, we use GalevNB to investigate the secular evolution of the spectral energy distribution (SED) and color magnitude diagram (CMD) of a simulated star cluster over a few hundred million years. With the results given by GalevNB we discover a UV-excess in the SED of the cluster over the whole simulation time. We also identify four candidates that contribute to the FUV peak: core helium burning stars, second asymptotic giant branch (AGB) stars, white dwarfs and naked helium stars.