We perform high-resolution cosmological hydrodynamic simulations to study the formation of the first galaxies that reach the masses of 10 8 - 9 h -1 M ⊙ at z = 9. The resolution of the simulations is high enough to resolve minihaloes and allow us to successfully pursue the formation of multiple Population (Pop) III stars, their supernova (SN)

Elemental abundances of the most metal-poor stars reflect the conditions in the early Galaxy and the properties of the first stars. We present a spectroscopic follow-up of two ultra-metal-poor stars ([Fe/H] < -4.0) identified by the survey Pristine: Pristine 221.8781+9.7844 and Pristine 237.8588+12.5660 (hereafter Pr 221 and Pr 237, respectively)

We report on the visible LGS-AO experimental facility which we are building to be installed at the 1m ESA Optical Ground Station at Observatorio del Teide, Tenerife, Canary Islands. We focus on the system aspects related to optics. The instrument will be a novel facility to perform strategic LGS-AO technology R&D in future years, demonstrating a 50

In this new era of extensive variability surveys, classical pulsators such as RR Lyrae stars (RRLs) and Classical Cepheids play a crucial role. We focus our attention on the use of RRLs as tracers of the oldest stellar populations of the Galactic halo (Halo) and we compare their properties to those hosted by nearby Milky Way (MW) satellites. These

We present our analysis of a large sample (over 150k) of candidate Galactic RR Lyrae (RRL) stars for which we derived high quality photometry at UV, optical and infrared wavelengths, using data from publicly available surveys. For a sub-sample of these stars (∼ 2,400 fundamental mode field RRLs) we have measured their individual metallicity using

We investigate the properties of pulsating variable stars in two galaxies at the edge or nearby the Local Group: VV 124 and KKr 25, located at ∼1.3 and ∼2 Mpc, respectively. We have identified well populated samples of RR Lyrae stars and Cepheids in both systems. We discuss how these can be used to trace the properties of different stellar