This thesis comprises of a full search in our galaxy for the hidden population of massive stars using the near-infrared photometry with a novel method and a quantitative spectroscopy study of an O star sample in the optical and near-infrared. Massive clusters are those with mass greater than 10^4 Solar Masses . The number of known massive clusters

Context. One of the key questions of the star formation problem is whether brown dwarfs (BDs) form in the manner of stars directly from the gravitational collapse of a molecular cloud core (star-like) or whether BDs and some very low-mass stars (VLMSs) constitute a separate population that forms alongside stars comparable to the population of

We present a galaxy classification system for 238 (E1-Sdm) CALIFA (Calar Alto Legacy Integral Field Area) galaxies based on the shapes and amplitudes of their circular velocity curves (CVCs). We infer the CVCs from the de-projected surface brightness of the galaxies, after scaling by a constant mass-to-light ratio based on stellar dynamics -

We analyse in detail the spatial distribution and kinematic properties of two different stellar populations in Andromeda II dwarf spheroidal galaxy. We obtained their detailed surface density maps together with their radial density profiles. The two populations differ not only in age and metallicity, but also in their spatial distribution and

This data paper presents lightcurves of 101 near Earth asteroids (NEAs) observed mostly between 2014 and 2017 as part of the EURONEAR photometric survey using 11 telescopes with diameters between 0.4 and 4.2 m located in Spain, Chile, Slovakia and Romania. Most targets had no published data at the time of observing, but some objects were observed

The production of jets in association with Z bosons, reconstructed via the μ+μ- and e+e- decay channels, is studied in p p and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%-30%