We study the observed correlation between atomic gas content and the likelihood of hosting a large-scale bar in a sample of 2090 disc galaxies. Such a test has never been done before on this scale. We use data on morphologies from the Galaxy Zoo project and information on the galaxies’ H I content from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) blind H I survey. Our main result...

We report the discovery of significant stellar substructure in the halo and outer disk of our nearest large galactic neighbour, M31. Our deep panoramic survey with the Isaac Newton Telescope Wide Field Camera currently maps out an area of ≈ 25 ⊓⊔ around M31, extending along the semi-major axis to 55 kpc, and is the first to allow an uninterrupted study of the density and color distribution of i...

We present resolved stellar photometry of 4 fields along the major axis of the M33 disk from images taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The photometry provides a detailed census of the red clump in all fields and reaches the ancient main sequence in the outermost field. Through detailed modeling of the color-magnitude diagrams, we find that the percenta...

We have used the Hubble Space Telescope and Wide Field Planetary Camera 2 to image the putative tidal dwarf galaxy located at the tip of the Southern tidal tail of NGC 4038/9, the Antennae. We resolve individual stars, and identify two stellar populations. Hundreds of massive stars are present, concentrated into tight OB associations on scales of 200 pc, with ages ranging from 2-100 Myr. An old...

We present the evolution of the volume averaged properties of the rest-frame optically luminous galaxy population to z ∼ 3, determined from four disjoint deep fields with optical to near-infrared wavelength coverage. Our use of independent lines of sight substantially mitigates field-to-field variations. We select galaxies above a fixed rest-frame V -band luminosity of 3× 10 h 70 L⊙ and charact...

We have incorporated the latest release of the Padova models into the evolutionary synthesis code Starburst99. The Padova tracks were extended to include the full asymptotic giant branch (AGB) evolution until the final thermal pulse over the mass range 0.9 to 5 M⊙. With this addition, Starburst99 accounts for all stellar phases that contribute to the integrated light of a stellar population wit...

The single star-stellar population (ss-SSP) models are usually used for stellar population studies. However, there are more than 50% stars that are in binaries and evolve differently from single stars. This suggests when we model the stellar populations of galaxies and star clusters, the effects of binary interactions should be considered. Although a few works tried to model stellar populations...

We present high signal to noise ratio Spitzer Infrared Spectrograph observations of 17 Virgo early-type galaxies. The galaxies were selected from those that define the colour-magnitude relation of the cluster, with the aim of detecting the silicate emission of their dusty, masslosing evolved stars. To flux calibrate these extended sources we have devised a new procedure that allows us to obtain...

We have tested the application to Sloan Digital Sky Survey data of the software package MATCH, which fits color-magnitude diagrams (CMDs) to estimate stellar population parameters and distances. These tests on a set of six globular clusters show that these techniques recover their known properties. New ways of using the CMD-fitting software enable us to deal with an extended distribution of sta...

We use a cosmological numerical simulation to study the tidal features produced by a minor merger with an elliptical galaxy. We find that the simulated tidal features are quantitatively similar to the red tidal features, i.e., dry tidal features, recently found in deep images of elliptical galaxies at intermediate redshifts. The minor merger in our simulation does not trigger star formation due...