Related papers: Disentangling the Hercules stream
(Abridged) We present a study of the optical spectra of a sample of eight star-forming nuclear rings and the nuclei of their host galaxies. The spectra were obtained with the ISIS spectrograph on the William Herschel Telescope and cover a…
We present imaging of the recently discovered Hercules Milky Way satellite and its surrounding regions to study its structure, star formation history and to thoroughly search for signs of disruption. We robustly determine the distance,…
Abundance trends in heavier elements with evolutionary phase have been shown to exist in the globular cluster NGC 6752 [Fe/H]=-1.6. These trends are a result of atomic diffusion and additional (non-convective) mixing. Studying such trends…
We have investigated the properties (e.g., age, metallicity) of the stellar populations of a ring-like tidal stellar stream (or streams) around the edge-on galaxy SPRC047 (z = 0.031) using spectral energy distribution (SED) fits to…
The assembly process of our Galaxy can be retrieved using the motions and chemistry of individual stars. Chemo-dynamical studies of the nearby halo have long hinted at the presence of multiple components such as streams, clumps, duality and…
The imprints of stellar nucleosynthesis and chemical evolution of the galaxy can be seen in different stellar populations, with older generation stars showing higher $\alpha$-element abundances while the later generations becoming enriched…
To place the highly substructured stellar halos of the Milky Way and M31 in a larger context of hierarchical galaxy formation, it is necessary to understand the prevalence and properties of tidal substructure around external galaxies. This…
Context. Recent studies have suggested that moving groups have a dynamic or "resonant" origin. Under this hypothesis, these kinematic structures become a powerful tool for studying the large-scale structure and dynamics of the Milky Way.…
We propose a new dynamical picture of galactic stellar and gas spirals, based on hydrodynamic simulations in a `live' stellar disk. We focus especially on spiral structures excited in a isolated galactic disk without a stellar bar. Using…
This work aims to investigate the behaviour of the lithium abundance in stars with and without detected planets. Our study is based on a sample of 1332 FGK main-sequence stars with measured lithium abundances, for 257 of which planets were…
The strong time-dependence of the dynamics of galactic bars yields a complex and rapidly evolving distribution of dense gas and star forming regions. Although bars mainly host regions void of any star formation activity, their extremities…
We investigate the stellar populations of a sample of Tidal Dwarf Galaxies, combining observations and evolutionary synthesis models to try and reveal their formation mechanism. On optical images we select a first sample of TDGs for which…
The Magellanic system comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), and the less frequently observed Magellanic Bridge and Magellanic Stream. The Bridge is traced by neutral gas and has an observed stellar…
In order to try and understand its origins, we present high-quality long-slit spectral observations of the counter-rotating stellar discs in the strange S0 galaxy NGC 4550. We kinematically decompose the spectra into two counter-rotating…
We investigate the hypothesized tidal disruption of the Hercules ultra-faint dwarf galaxy (UFD). Previous tidal disruption studies of the Hercules UFD have been hindered by the high degree of foreground contamination in the direction of the…
The four main findings about the age and abundance structure of the Milky Way bulge based on microlensed dwarf and subgiant stars are: (1) a wide metallicity distribution with distinct peaks at [Fe/H]=-1.09, -0.63, -0.20, +0.12, +0.41; (2)…
From a detailed elemental abundance analysis of 102 F and G dwarf stars we present abundance trends in the Galactic thin and thick disks for 14 elements (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, Ba, and Eu). Stellar parameters and…
With the prime aim of better probing and understanding the intimate link between star formation activity and the presence of bars, a representative sample of 32 non-interacting late-type galaxies with well-determined bar properties has been…
We present a deep, wide-field photometric survey of the newly-discovered Hercules dwarf spheroidal galaxy, based on data from the Large Binocular Telescope. Images in B, V and r were obtained with the Large Binocular Camera covering a 23'…
Galactic Archeology is a powerful tool for investigating the formation and evolution of the Milky Way. We use this technique to study kinematic groups of F- and G-stars in the solar neighbourhood. From correlations between orbital…