Related papers: Multiple stellar population in the Sextans dwarf s…

We combine the Dark Energy Camera Legacy Survey (DECaLS) DR8 photometry with Gaia photometry to study the 3-D structure of Bootes I, Draco, Ursa Minor, Sextans and Sculptor dwarf galaxies using blue horizontal branch (BHB) stars as distance…

The origin of the star-to-star abundance variations found for the light elements in Galactic globular clusters (GGCs) is not well understood, which is a significant problem for stellar astrophysics. While the light element abundance…

We use time-resolved spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to examine the distribution of radial velocity (RV) variations in 249 stars identified as members of the Sagittarius (Sgr) dwarf…

Dwarf spheroidal galaxies (dSph) orbiting the Milky Way are complex objects often with complicated star formation histories and internal dynamics. In this work, we search for stellar substructures in four of the classical dSph satellites of…

As part of the Dwarf galaxies Abundances and Radial-velocities Team (DART) program, we have measured the metallicities of a large sample of stars in four nearby dwarf spheroidal galaxies (dSph's): Sculptor, Sextans, Fornax, and Carina. The…

We present measurements of Fe, Mg, Si, Ca, and Ti abundances for 388 radial velocity member stars in the Sculptor dwarf spheroidal galaxy (dSph), a satellite of the Milky Way. This is the largest sample of individual alpha element (Mg, Si,…

Blue straggler star (BSS) candidates have been observed in all old dwarf spheroidal galaxies (dSphs), however whether or not they are authentic BSSs or young stars has been a point of debate. To both address this issue and obtain a better…

We present iron and $\alpha$ element (Mg, Ca, Ti) abundances for a sample of 15 Red Giant Branch stars belonging to the main body of the Sagittarius dwarf Spheroidal galaxy. Abundances have been obtained from spectra collected using the…

We report a new star formation history for the Tucana dwarf spheroidal galaxy, obtained from a new look at a deep HST/ACS colour-magnitude diagram. We combined information from the main sequence turn-off and the horizontal branch to resolve…

We present broad-band V and I imaging and long-slit spectroscopy in the optical range 3600-7500A of the dwarf irregular galaxy HS 1442+4250. The oxygen abundance 12+log(O/H)=7.63+/-0.02 (Z=Zsun/19) in the brightest H II region of HS…

We present a large sample of fully self-consistent hydrodynamical Nbody/Tree-SPH simulations of isolated dwarf spheroidal galaxies (dSphs). It has enabled us to identify the key physical parameters and mechanisms at the origin of the…

We present new Hubble Space Telescope photometry of the massive globular cluster M54 (NGC 6715) and the superposed core of the tidally disrupted Sagittarius (Sgr) dSph galaxy as part of the ACS Survey of Galactic Globular Clusters. Our deep…

In order to minimize environmental effects and gain an insight into the internal mechanisms that shape the properties of the early-type dwarf systems, we study one of the few isolated dwarf spheroidal galaxies (dSphs) of the Local Group…

We derive the star formation history (SFH) and chemical evolution history (CEH) of the Ursa Minor (UMi) dwarf spheroidal galaxy (dSph). We detect two distinct stellar populations that exist over 6 times half-light radius from its center.…

We present a detailed optical spectroscopic and B,V,I,Halpha photometric study of the metal-deficient cometary blue compact dwarf (BCD) galaxy SBS 1415+437. We derive an oxygen abundance 12+log(O/H)=7.61+/-0.01 and 7.62+/-0.03 (Z =Zsun/20)…

An increasing number of both photometric and spectroscopic observations over the last years have shown the existence of distinct sub-populations in many Galactic globular clusters and shattered the paradigm of globulars hosting single,…

Using the Keck Cosmic Web Imager we obtain spectra of several globular clusters (GCs), ultra compact dwarfs (UCDs) and the inner halo starlight of M87, at a similar projected galactocentric radius of $\sim$5 kpc. This enables us, for the…

We review our current knowledge of the population of high-redshift sub-mm/mm galaxies, with particular emphasis on recent results from the SCUBA HAlf Degree Extragalactic Survey (SHADES). All available evidence indicates that these objects…

We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I LRIS and Keck II DEIMOS spectrographs. Based on their g-i colors (taken with the…

The Sagittarius dwarf spheroidal (Sgr) and a few paculiar Galactic Globular Clusters (GGC) can be considered as building blocks of theGalactic Halo. We present a series of results based on a wide field photometry of the Sgr system and the…