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The galaxy group NGC 5044 consists of a luminous giant elliptical galaxy surrounded by a cluster of approximately 160 low luminosity and dwarf galaxies, mostly of early type. The cumulative projected radial distribution of dwarf galaxies in…
We study a sample of 5 dwarf irregular galaxies in the CenA/M83 group, which are companions to the giant elliptical CenA. We aim at deriving their physical properties over their lifetime and compare them to those of dwarfs located in…
Using data of five clusters of galaxies within the redshift range 0.15 $\leq$ z $\leq$ 0.25, imaged with the Nordic Optical Telescope (NOT) in the central $\approx$ 1 Mpc$^2$ in very good seeing conditions, we have performed an exhaustive…
The ALFALFA (Arecibo Legacy Fast ALFA) blind survey is providing a census of HI in galaxies of all types in a range of environments. Here we report on ALFALFA results for Virgo Cluster early-type dwarfs between declinations of 4 and 16…
Elliptical and S0 galaxies dominate the galaxy population in nearby rich clusters such as Coma. Studies of the evolution of the colors, M/L ratios, and line indices of early-type galaxies indicate that they have been a highly homogeneous,…
We measure the morphology-density relation of galaxies at z=1 across the full three orders of magnitude in projected galaxy density available in low-redshift studies. Our study adopts techniques that are comparable with those applied at…
Information on the star-formation histories of cD galaxies and their extended stellar haloes lie in their spectra. Therefore, to determine whether these structures evolved together or through a two-phase formation, we need to…
One of the largest uncertainties in understanding the effect of a background UV field on galaxy formation is the intensity and evolution of the radiation field with redshift. This work attempts to shed light on this issue by computing the…
Radial surface brightness profiles of spiral galaxies are classified into three types: (I) single exponential, or the light falls off with one exponential to a break before falling off (II) more steeply, or (III) less steeply. Profile…
We present 3.5m Apache Point Observatory second-epoch spectra of four low-metallicity emission-line dwarf galaxies discovered serendipitously in the Data Release 5 of the Sloan Digital Sky Survey (SDSS) to have extraordinary large broad…
We present an analysis of HI, H-alpha, and oxygen abundance data for NGC 3741. This galaxy has a very extended gas disk (~8.8 times the Holmberg radius), and a dark to luminous (i.e. stellar) mass ratio of ~149, which makes it one of the…
Detailed surface photometry for 79 (mostly dwarf) galaxies in the NGC 5044 Group area is analysed, revealing the existence of different morphologies among objects originally classified as early-type dwarfs. Particularly, a significant…
We investigate the structural properties of the underlying hosts of 34 blue compact dwarf (BCD) galaxies with deep near-infrared (NIR) photometry. The BCD sample is selected from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey…
We present the first HI spectral line images of the nearby, star-forming dwarf galaxies UGC11411 and UGC 8245, acquired as part of the "Observing for University Classes" program with the Karl G. Jansky Very Large Array (VLA). These…
We exclude hydrogen burning stars, of any mass above the hydrogen-burning limit and any metallicity, as significant contributors to the massive halos deduced from rotation curves to dominate the outer parts of spiral galaxies. We present…
Keck spectroscopy and Hubble Space Telescope WFPC2 imaging over a 1.5x1.5 Mpc field of CL1358+62 at z=0.33 are used to study the Fundamental Plane of galaxies based on a new, large sample of 53 galaxies. First, we have constructed the…
We have observed the J=3-2 transition of N2H+ and N2D+ to investigate the trend of deuterium fractionation with evolutionary stage in three selected regions in the Infrared Dark Cloud (IRDC) G28.34+0.06 with the Submillimeter Telescope…
We present high-quality aperture synthesis observations of the neutral hydrogen distribution in a sample of five galactic systems believed to be involved in progressive stages of merging: Arp295, NGC4676, NGC520, NGC3921, and NGC7252. These…
We present optical imaging and spectroscopy and HI imaging of the Virgo Cluster galaxy IC 3418, which is likely a "smoking gun" example of the transformation of a dwarf irregular into a dwarf elliptical galaxy by ram pressure stripping. IC…
We examine the UV emission from luminous early-type galaxies as a function of redshift. We perform a stacking analysis using Galaxy Evolution Explorer (GALEX) images of galaxies in the NOAO Deep Wide Field Survey (NDWFS) Bo\"otes field and…