In order to fully understand the gravitational collapse of molecular clouds, the star formation process, and the evolution of circumstellar disks, these phenomena must be studied in different Galactic environments with a range of stellar contents and positions in the Galaxy. The young massive association Cygnus OB2, in the Cygnus-X region, is a unique target to study how star formation and the evolution of circumstellar disks proceed in the presence of a large number of massive stars. We present a catalog obtained with recent optical observations in the r, i, z filters with OSIRIS, mounted on the 10.4 m Gran Telescopio CANARIAS telescope, which is the deepest optical catalog of Cyg OB2 to date. The catalog consists of 64,157 sources down to M = 0.15 M ☉ at the adopted distance and age of Cyg OB2. A total of 38,300 sources have good photometry in all three bands. We combined the optical catalog with existing X-ray data of this region, in order to define the cluster locus in the optical diagrams. The cluster locus in the r – i versus i – z diagram is compatible with an extinction of the optically selected cluster members in the 2.64 m < AV < 5.57 m range. We derive an extinction map of the region, finding a median value of AV = 4.33 m in the center of the association, decreasing toward the northwest. In the color-magnitude diagrams, the shape of the distribution of main-sequence stars is compatible with the presence of an obscuring cloud in the foreground ~850 ± 25 pc from the Sun.
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We present the results of our spatially resolved investigation into the interplay between the ages of the stellar populations and the kinematics of the warm ionised outflows in the well-studied type II quasar Markarian 34. Utilising integral field spectroscopic (IFS) data, we determine the spatial distribution of the young stellar population (YSP; age < 100 Myr) using spectral synthesis modelling. We also employ the 5007 [OIII] emission line as a tracer of the warm ionised gas kinematics. We demonstrate a spatial correlation between the outer edges of the advancing side of the outflow and an
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Puzzling properties of massive early-type galaxies (ETGs) emerge when studying their spectra at near-infrared (NIR) wavelengths. Massive ETGs show strong CO absorption features in their H and K band spectra that cannot be explained by state-of-the-art stellar population models. For many years, the disagreement has been attributed to the presence of intermediate-age (0.1-2 Gyr) stellar populations in these galaxies, as the NIR light of intermediate-age stellar populations is dominated by cool stars (e.g. asymptotic giant branch (AGB) stars) that show strong CO absorptions in their spectrum
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In this work we discuss and confront recent results on metallicity variations in the local interstellar medium, obtained from observations of H II regions by our group and neutral clouds (from literature) of the Galactic thin disk, and compare them with recent high-quality metallicity determinations of other tracers of the chemical composition of the interstellar medium as B-type stars, classical Cepheids, and young clusters. We find that the metallicity variations obtained for these last kinds of objects are consistent with each other and with that obtained for H II regions but
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