Abstract. We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types from S0/a to Im and with recession velocities of between 0 and 3000 km s −1 . The basic data for each galaxy are narrow band Hα+ [N] and R-band imaging, from which we derive star formation rates, Hα+[N] equivalent widths and surface brightnesses, and R-band total magnitudes. A strong correlation is found between total star formation rate and Hubble type, with the strongest star formation in isolated galaxies occurring in Sc and Sbc types. More surprisingly, no significant trend is found between Hα+[N] equivalent width and galaxy R-band luminosity. More detailed analyses of the data set presented here will be described in subsequent papers.

Abstract. We determine ages of 71 old Open Clusters by a two-step method: we use main-squence fitting to 10 selected clusters, in order to obtain their distances, and derive their ages from comparison with our own isochrones used before for Globular Clusters. We then calibrate the morphological age indicator δ(V), which can be obtained for all remaining clusters, in terms of age and metallicity. Particular care is taken to ensure consistency in the whole procedure. The resulting Open Cluster ages connect well to our previous Globular Cluster results. From the Open Cluster sample, as well as from the combined sample, questions regarding the formation process of Galactic components are addressed. The age of the oldest open clusters (NGC 6791 and Be 17) is of the order of 10 Gyr. We determine a delay by 2.0 ± 1.5 Gyr between the start of the halo and thin disk formation, whereas thin and thick disk started to form approximately at the same time. We do not find any significant agemetallicity relationship for the open cluster sample. The cumulative age distribution of the whole open cluster sample shows a moderately significant (∼2σ level) departure from the predictions for an exponentially declining dissolution rate with timescale of 2.5 Gyr. The cumulative age distribution does not show any trend with galactocentric distance, but the clusters with larger height to the Galactic plane have an excess of objects between 2-4 and 6 Gyr with respect to their counterpart closer to the plane of the Galaxy.

We present a new grid of stellar models and isochrones for old stellar populations, covering a large range of [Fe/H] values, for an heavy element mixture characterized by CNONa abundance anticorrelations as observed in Galactic globular cluster stars. The effect of this metal abundance pattern on the evolutionary properties of low mass stars, from the main sequence to the horizontal branch phase is analyzed. We perform comparisons between these new models, and our reference α−enhanced calculations, and discuss briefly implications for CMDs showing multiple main sequence or subgiant branches. A brief qualitative discussion of the effect of CN abundances on color-T ef f transformations is also presented, highlighting the need to determine theoretical color transformations for the appropriate metal mixture, if one wants to interpret observations in the Strömgren system, or broadband filters blueward of the Johnson V -band.

We present a study of the properties of the host galaxies of unusual transient objects of two types, both being sub-luminous compared with the major classes of supernovae. Those of one type exhibit unusually strong calcium features, and have been termed 'Ca-rich'. Those of the second type, with SN2002cx as the prototype and SN2008ha as the most extreme example to date, have some properties in common with the first, but show typically lower ejecta velocities, and different early spectra. We confirm important differences in the environments of the two types, with the Ca-rich transients preferentially occurring in galaxies dominated by old stellar populations. Quantitatively, the association of the the Ca-rich transients with regions of ongoing star formation is well matched to that of type Ia supernovae. The SN2002cx-like transients are very different, with none of the present sample occurring in an early-type host, and a statistical association with star-formation regions similar to that of type II-P supernovae, and therefore a delay time of 30-50 Myrs.

This paper is the 4th in a series describing the latest additions to the BaSTI stellar evolution database, which consists of a large set of homogeneous models and tools for population synthesis studies, covering ages between 30 Myr and ∼20 Gyr and 11 values of Z (total metallicity). Here we present a new set of low and high resolution synthetic spectra based on the BaSTI stellar models, covering a large range of simple stellar populations (SSPs) for both scaled solar and α-enhanced metal mixtures. This enables a completely consistent study of the photometric and spectroscopic properties of both resolved and unresolved stellar populations, and allows us to make detailed tests on specific factors which can affect their integrated properties. Our low resolution spectra are suitable for deriving broadband magnitudes and colors in any photometric system. These spectra cover the full wavelength range (9-160000nm) and include all evolutionary stages up to the end of AGB evolution. Our high resolution spectra are suitable for studying the behaviour of line indices and we have tested them against a large sample of Galactic globular clusters. We find that the range of ages, iron abundances [Fe/H], and degree of α-enhancement predicted by the models matches the observed values very well. We have also tested the global consistency of the BaSTI models by making detailed comparisons between ages and metallicities derived from isochrone fitting to observed colour-magnitude diagrams, and from line index strengths, for the Galactic globular cluster 47 Tuc and the open cluster M67. For 47 Tuc we find reasonable agreement between the 2 methods, within the estimated errors. From the comparison with M67 we find non-negligible effects on derived line indices caused by statistical fluctuations, which are a result of the specific method used to populate an isochrone and assign appropriate spectra to individual stars.