Related papers: The Villafranca project: Combining Gaia and ground…

(ABRIDGED) CONTEXT: The Villafranca project is combining Gaia data with ground-based surveys to analyze Galactic stellar groups with OB stars. AIMS: We want to analyze Stock 18 within the Villafranca project, a very young stellar cluster…

CONTEXT. This is the second paper of a series on Galactic OB groups that uses astrometric and photometric data from Gaia and spectral classifications from GOSSS and LiLiMaRlin. The previous paper was based on Gaia DR2, this is based on Gaia…

CONTEXT. The GOSSS spectral classifications and Gaia data have significantly improved our ability to measure distances and determine memberships of stellar groups with OB stars. AIMS. We have started a program to identify, measure…

The distribution of young stars into OB associations has long been in need of updating. High-precision {\sl Gaia} early Data Release 3 astrometry, coupled with modern machine-learning methods, allows this to be done. We have compiled a…

The IACOB spectroscopic survey of Galactic OB stars is an ambitious observational project aimed at compiling a large, homogeneous, high-resolution database of optical spectra of massive stars observable from the Northern hemisphere. The…

Stellar clusters are important for astrophysics in many ways, for instance as optimal tracers of the Galactic populations to which they belong or as one of the best test bench for stellar evolutionary models. Gaia DR1, with TGAS, is just…

Context: Star clusters, composed of stars born from the same molecular cloud, serve as invaluable natural laboratories for understanding the fundamental processes governing stellar formation and evolution. Aims: This study aims to…

Low-density and unbound stellar groups, OB associations have been historically delineated through their bright and massive members. They have been analysed for decades, but the arrival of Hipparcos, and more recently of Gaia led to a change…

Open clusters and associations are groups of young stars, respectively bound and unbound, that share the same origin and disperse over time into the galactic field. As such, their formation and evolution are the key to understand the origin…

Star clusters are crucial for understanding how stars evolve. Their colour-magnitude diagrams show the effects of stellar evolution of approximately coeval objects with the same chemical composition. Furthermore, the determination of their…

Both star clusters and variable stars are sensitive laboratories of stellar astrophysics and evolution: cluster member stars provide context for interpreting cluster populations, whereas variability reveals the nature of individual stellar…

The second data release of ESA's Gaia satellite (Gaia DR2) revolutionised astronomy by providing accurate distances, proper motions, apparent magnitudes, and in many cases temperatures and radial velocities for an unprecedented number of…

Context. The astrometric satellite Gaia is expected to significantly increase our knowledge as to the properties of the Milky Way. The Gaia Early Data Release 3 (Gaia EDR3) provides the most precise parallaxes for many OB stars, which can…

In this review I discuss different theories of the formation of OB associations in the Milky Way, and provide the observational evidences in support of them. In fact, the second release of Gaia astrometric data (April 2018) is…

In the era of large high-resolution spectroscopic surveys, high-quality spectra can contribute to our understanding of the Galactic chemical evolution, providing chemical abundances belonging to the different nucleosynthesis channels, and…

Symbiotic stars, binary pairs with a cool giant fueling accretion onto a hot compact companion, offer unique insights to our understanding of stellar evolution. Yet, only a few hundred symbiotic stars are confirmed. Here, we report on a new…

The Gaia data will help to improve the construction of a luminosity function for the disk and the halo and will provide a more accurate determination of the age of our solar neighborhood. Moreover, reliable stellar dynamical investigations…

Most stars in our Galaxy form in stellar aggregates, which can become long-lived structures called open clusters (OCs). Along their dynamical evolution, their gradual depletion leave some imprints on their structure. In this work, we…

Empirical and theoretical studies have demonstrated that the periods of Mira variable stars are related to their ages. This, together with their brightness in the infrared, makes them powerful probes of the formation and evolution of…

One of the most promising space missions of ESA is the astrometric satellite Gaia, which will provide very precise astrometry and multicolour photometry, for all 1.3 billion objects to V~20, and radial velocities with accuracies of a few…