Secondary globular cluster populations

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Star Formation in Galaxy Mergers: Scaling up a universal process or a violent mode of SF

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Star Formation in Violent and Normal Evolutionary Phases

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Properties of YMCs Derived from Photometry

Original article can be found at: http://www.astrosociety.org/pubs/cs/309.html--Copyright Astronomical Society of the PacificI will show that photometry { if extending over a reasonable choice of passbands { can give fairly precise information about young star clusters and their evolutionary state. Optical colors alone are known to leave severe ambiguities due to degeneracies between age, metallicity and extinction. High quality photometry including U;B; V or I, and a NIR band, however, in combination with an extensive grid of evolutionary synthesis models for star clusters and a dedicated tool to analyse spectral energy distributions allows to assess and largely disentangle star cluster ages, metallicities, extinction values and, hence, to derive their masses. Gaseous emission contributions sensibly affect broad band colors during the youngest stages, depending on metallicity. Mass functions of young star cluster systems may considerably differ in shape from luminosity functions. An ESO ASTROVIRTEL project provides multi-color photometry for a large number of young, intermediate age and old star cluster systems. As a first example I show results obtained for NGC 1569

The role of E+A and post-starburst galaxies – I. Models and model results

‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.14416.xDifferent compositions of galaxy types in the field in comparison to galaxy clusters as described by the morphology–density relation in the local universe are interpreted as a result of transformation processes from late- to early-type galaxies. This interpretation is supported by the Butcher–Oemler effect. We investigate E+A galaxies as an intermediate state between late-type galaxies in low-density environments and early-type galaxies in high-density environment to constrain the possible transformation processes. For this purpose, we model a grid of post-starburst galaxies by inducing a burst and/or a halting of star formation on the normal evolution of spiral galaxies with our galaxy evolution code galev. From our models, we find that the common E+A criteria exclude a significant number of post-starburst galaxies, and propose that comparing their spectral energy distributions leads to a more sufficient method to investigate post-starburst galaxies. We predict that a higher number of E+A galaxies in the early universe cannot be ascribed solely to a higher number of starburst, but is a result of a lower metallicity and a higher burst strength due to more gas content of the galaxies in the early universe. We find that even galaxies with a normal evolution without a starburst have an Hδ-strong phase at early galaxy ages.Peer reviewe

Tidal dwarf candidates in a sample of interacting galaxies: II. Properties and kinematics of the ionized gas

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