The formation of two stellar bars within a galaxy has proved challenging for numerical studies. It is not yet clear whether the inner bar is born via a star formation process promoted by gas inflow along the outer bar or whether it is dynamically assembled from instabilities in a small-scale stellar disc. Observational constraints to these

We present an analysis of the Ultraviolet and Visual Echelle Spectrograph (UVES) high-resolution spectroscopic observations at the 8.2 m Very Large Telescope of J0023+0307, a main-sequence extremely iron-poor dwarf star. We are unable to detect iron lines in the spectrum but derive [Fe/H] -6.1 from the Ca II resonance lines assuming [Ca/Fe] ≥ 0.40

If astronomy can be understood as the contemplation of the sky for any given purpose, we must realize that possibly all societies throughout time and in all regions have watched the sky. The why, who, how and when of such investigation is the pursuit of cultural astronomy. When the research is done with the archaeological remains of a given society

Aims: The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances. Methods: We derived different sets of ages using Padova and Yonsei-Yale isochrones and HIPPARCOS and Gaia parallaxes for a sample

The possible existence of two dark-matter-free galaxies (NGC 1052-DF2 and NGC 1052-DF4) in the field of the early-type galaxy NGC 1052 presents a challenge to theories of dwarf galaxy formation according to the current cosmological paradigm. We carried out a search for signatures of past interactions connected to the putative hosts of NGC 1052-DF2

Many white dwarf stars show signs of having accreted smaller bodies, implying that they may host planetary systems. A small number of these systems contain gaseous debris discs, visible through emission lines. We report a stable 123.4-minute periodic variation in the strength and shape of the Ca II emission line profiles originating from the debris