Aims. We study the stellar population of local infrared galaxies, which contain star-forming galaxies, composite galaxies, LINERs, and Seyfert 2s. We also want to find whether infrared luminosity and spectral class have any effect on their stellar populations. Methods. The sample galaxies are selected from the main galaxy sample of SDSS-DR4 and then cross-correlated with the IRASPSCz catalog. W...

We present initial results from a wide field photometric survey of the Fornax dwarf spheroidal (dSph) galaxy. The focus here is on a small overdensity of stars located approximately 17 (670 pc in projection) from the centre of Fornax. Based on imaging data in both V and I bands down to V ≈ 21, the dimensions of the feature are ∼1.7×3.2 (68×128 pc) with an average surface brightness of 25.8 mag/...

We determine relative stellar ages and metallicities mainly for about 80 elliptical galaxies in low and high density environments via the latest binary stellar population (BSP) synthesis model and test a latest hierarchical formation model of elliptical galaxies which adopted the new ΛCDM cosmology for the first time. The stellar ages and metallicities of galaxies are estimated from two high-qu...

The relationship of an AGN to its host galaxy is one crucial question in the study of galaxy evolution. We present a method to estimate the stellar contribution in active galactic nuclei. We perform stellar population synthesis in the central regions of a sample of 12 galaxies of different levels of activity: normal galaxies, starburst galaxies, LINERs, Seyfert 2 and Seyfert 1 galaxies. Quantif...

Starburst galaxies are powered by massive stars. These stars dominate the heating and enrichment with heavy elements of the interstellar medium, gas out of which new stars form. Thus, high-mass stars, and in consequence starburst galaxies, are an important (in some cases the dominant) energy source for the evolution of galaxies and the universe. In this contribution I review techniques to deriv...

Galactic stellar halos have long been considered to contain fossil information on early dynamical and chemical evolution of galaxies. We propose that the surface brightness distributions of old stellar halos contain the influence of reionization on early formation histories of galaxies. By assuming that reionization significantly suppresses star formation in small subgalactic clumps virialized ...

Using the Hubble Space Telescope/Advanced Camera for Surveys data in the COSMOS field, we systematically searched clumpy galaxies at 0.2 < z < 1.0 and investigated the fraction of clumpy galaxies and its evolution as a function of stellar mass, star formation rate (SFR), and specific SFR (SSFR). The fraction of clumpy galaxies in star-forming galaxies with Mstar > 10 M⊙ decreases with time from...

We present first results from a Keck/DEIMOS spectroscopic survey of red giant branch (RGB) stars in M33. The radial velocity distributions of the stars in our fields are well described by three Gaussian components, corresponding to a candidate halo component with an uncorrected radial velocity dispersion of σ ≃ 50 km s, a candidate disk component with a dispersion σ ≃ 16 km s, and a third compo...

The metallicity distribution function (MDF) for the old red-giant stars in the halo of NGC 5128, the nearest giant elliptical galaxy, is virtually identical with the MDF for the old-disk stars in the LMC and also strongly resembles the halo MDF in M31. These galaxies all have high mean halo metallicities (〈m/H〉 ≃ −0.4) with very small proportions of low-metallicity stars. These observations rei...

We use a sample of 87 rest-frame ultraviolet-selected star-forming galaxies with mean spectroscopic redshift 〈z〉 = 2.26±0.17 to study the correlation between metallicity and stellar mass at high redshift. Using stellar masses determined from spectral energy distribution fitting to UnGRJKs (and Spitzer IRAC, for 37% of the sample) photometry, we divide the sample into six bins in stellar mass, a...