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The ESO public survey VISTA Variables in the V\'ia L\'actea (VVV) surveyed the inner Galactic bulge and the adjacent southern Galactic disk from $2009-2015$. Upon its conclusion, the complementary VVV eXtended (VVVX) survey has expanded both the temporal as well as spatial coverage of the original VVV area, widening it from $562$ to $1700$ sq. deg., as well as providing additional epochs in $JHK_{\rm s}$ filters from $2016-2023$. With the completion of VVVX observations during the first semester of 2023, we present here the observing strategy, a description of data quality and access, and the legacy of VVVX. VVVX took $\sim 2000$ hours, covering about 4% of the sky in the bulge and southern disk. VVVX covered most of the gaps left between the VVV and the VISTA Hemisphere Survey (VHS) areas and extended the VVV time baseline in the obscured regions affected by high extinction and hence hidden from optical observations. VVVX provides a deep $JHK_{\rm s}$ catalogue of $\gtrsim 1.5\times10^9$ point sources, as well as a $K_{\rm s}$ band catalogue of $\sim 10^7$ variable sources. Within the existing VVV area, we produced a $5D$ map of the surveyed region by combining positions, distances, and proper motions of well-understood distance indicators such as red clump stars, RR Lyrae, and Cepheid variables. In March 2023 we successfully finished the VVVX survey observations that started in 2016, an accomplishment for ESO Paranal Observatory upon 4200 hours of observations for VVV+VVVX. The VVV+VVVX catalogues complement those from the Gaia mission at low Galactic latitudes and provide spectroscopic targets for the forthcoming ESO high-multiplex spectrographs MOONS and 4MOST., Comment: 17 pages, 11 figures (+ appendix). Accepted for publication in Astronomy and Astrophysics in section 14: Catalogs and data

We fit various colour-magnitude diagrams (CMDs) of the high-latitude Galactic globular clusters NGC\,5024 (M53), NGC\,5053, NGC\,5272 (M3), NGC\,5466, and NGC\,7099 (M30) by isochrones from the Dartmouth Stellar Evolution Database and Bag of Stellar Tracks and Isochrones for $\alpha$-enrichment [$\alpha$/Fe]$=+0.4$. For the CMDs, we use data sets from {\it Hubble Space Telescope}, {\it Gaia}, and other sources utilizing, at least, 25 photometric filters for each cluster. We obtain the following characteristics with their statistic uncertainties for NGC\,5024, NGC\,5053, NGC\,5272, NGC\,5466, and NGC\,7099, respectively: metallicities [Fe/H]$=-1.93\pm0.02$, $-2.08\pm0.03$, $-1.60\pm0.02$, $-1.95\pm0.02$, and $-2.07\pm0.04$ dex with their systematic uncertainty 0.1 dex; ages $13.00\pm0.11$, $12.70\pm0.11$, $11.63\pm0.07$, $12.15\pm0.11$, and $12.80\pm0.17$ Gyr with their systematic uncertainty 0.8 Gyr; distances (systematic uncertainty added) $18.22\pm0.06\pm0.60$, $16.99\pm0.06\pm0.56$, $10.08\pm0.04\pm0.33$, $15.59\pm0.03\pm0.51$, and $8.29\pm0.03\pm0.27$ kpc; reddenings $E(B-V)=0.023\pm0.004$, $0.017\pm0.004$, $0.023\pm0.004$, $0.023\pm0.003$, and $0.045\pm0.002$ mag with their systematic uncertainty 0.01 mag; extinctions $A_\mathrm{V}=0.08\pm0.01$, $0.06\pm0.01$, $0.08\pm0.01$, $0.08\pm0.01$, and $0.16\pm0.01$ mag with their systematic uncertainty 0.03 mag, which suggest the total Galactic extinction $A_\mathrm{V}=0.08$ across the whole Galactic dust to extragalactic objects at the North Galactic pole. The horizontal branch morphology difference of these clusters is explained by their different metallicity, age, mass-loss efficiency, and loss of low-mass members in the evolution of the core-collapse cluster NGC\,7099 and loose clusters NGC\,5053 and NGC\,5466., Comment: 9 figures, published in Research in Astronomy and Astrophysics

Canis Major OB1 (CMa OB1) is a Galactic stellar association with a very intriguing star-formation scenario. There are more than two dozen known star clusters in its line of sight, but it is not clear which ones are physically associated with CMa OB1. We use a clustering code that employs 5-dimensional data from the Gaia DR2 catalogue to identify physical groups and obtain their astrometric parameters and, in addition, we use two different isochrone-fitting methods to estimate the ages of these groups. We find 15 stellar groups with distances between 570 pc and 1650 pc, including 10 previously known and 5 new open cluster candidates. Four groups, precisely the youngest ones ($<$ 20 Myr), CMa05, CMa06, CMa07 and CMa08, are confirmed to be part of CMa OB1. We find that CMa08, a new cluster candidate, may be the progenitor cluster of runaway stars. CMa06 coincides with the well-studied CMa R1 star-forming region. While CMa06 is still forming stars, due to the remaining material of the molecular cloud associated with the Sh 2-262 nebula, CMa05, CMa07 and CMa08 seem to be in more evolved stages of evolution, with no recent star-forming activity. The properties of these CMa OB1 physical groups fit well in a monolithic scenario of star formation, with a common formation mechanism, and having suffered multiple episodes of star formation. This suggests that the hierarchical model alone, which explains the populations of other parts of the same association, is not sufficient to explain its whole formation history., Comment: 23 pages, 28 figures, 7 tables

The Southern Photometric Local Universe Survey (S-PLUS) is imaging ~9300 deg^2 of the celestial sphere in twelve optical bands using a dedicated 0.8 m robotic telescope, the T80-South, at the Cerro Tololo Inter-American Observatory, Chile. The telescope is equipped with a 9.2k by 9.2k e2v detector with 10 um pixels, resulting in a field-of-view of 2 deg^2 with a plate scale of 0.55"/pixel. The survey consists of four main subfields, which include two non-contiguous fields at high Galactic latitudes (8000 deg^2 at |b| > 30 deg) and two areas of the Galactic plane and bulge (for an additional 1300 deg^2). S-PLUS uses the Javalambre 12-band magnitude system, which includes the 5 u, g, r, i, z broad-band filters and 7 narrow-band filters centered on prominent stellar spectral features: the Balmer jump/[OII], Ca H+K, H-delta, G-band, Mg b triplet, H-alpha, and the Ca triplet. S-PLUS delivers accurate photometric redshifts (delta_z/(1+z) = 0.02 or better) for galaxies with r < 20 AB mag and redshift < 0.5, thus producing a 3D map of the local Universe over a volume of more than 1 (Gpc/h)^3. The final S-PLUS catalogue will also enable the study of star formation and stellar populations in and around the Milky Way and nearby galaxies, as well as searches for quasars, variable sources, and low-metallicity stars. In this paper we introduce the main characteristics of the survey, illustrated with science verification data highlighting the unique capabilities of S-PLUS. We also present the first public data release of ~336 deg^2 of the Stripe-82 area, which is available at http://datalab.noao.edu/splus., Comment: Updated to reflect the published version (MNRAS, 489, 241). For a short introductory video of the S-PLUS project, see https://youtu.be/yc5kHrHU9Jk - The S-PLUS Data Release 1 is available at http://datalab.noao.edu/splus

We present a new methodology for the estimation of stellar atmospheric parameters from narrow- and intermediate-band photometry of the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a method for target pre-selection of low-metallicity stars for follow-up spectroscopic studies. Photometric metallicity estimates for stars in the globular cluster M15 are determined using this method. By development of a neural-network-based photometry pipeline, we aim to produce estimates of effective temperature, $T_{\rm eff}$, and metallicity, [Fe/H], for a large subset of stars in the J-PLUS footprint. The Stellar Photometric Index Network Explorer, SPHINX, is developed to produce estimates of $T_{\rm eff}$ and [Fe/H], after training on a combination of J-PLUS photometric inputs and synthetic magnitudes computed for medium-resolution (R ~ 2000) spectra of the Sloan Digital Sky Survey. This methodology is applied to J-PLUS photometry of the globular cluster M15. Effective temperature estimates made with J-PLUS Early Data Release photometry exhibit low scatter, \sigma($T_{\rm eff}$) = 91 K, over the temperature range 4500 < $T_{\rm eff}$ (K) < 8500. For stars from the J-PLUS First Data Release with 4500 < $T_{\rm eff}$ (K) < 6200, 85 $\pm$ 3% of stars known to have [Fe/H] <-2.0 are recovered by SPHINX. A mean metallicity of [Fe/H]=-2.32 $\pm$ 0.01, with a residual spread of 0.3 dex, is determined for M15 using J-PLUS photometry of 664 likely cluster members. We confirm the performance of SPHINX within the ranges specified, and verify its utility as a stand-alone tool for photometric estimation of effective temperature and metallicity, and for pre-selection of metal-poor spectroscopic targets., Comment: 18 pages, 12 figures

J-PLUS is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern hemisphere from the dedicated JAST/T80 telescope at the Observatorio Astrof\'isico de Javalambre. T80Cam is a 2 sq.deg field-of-view camera mounted on this 83cm-diameter telescope, and is equipped with a unique system of filters spanning the entire optical range. This filter system is a combination of broad, medium and narrow-band filters, optimally designed to extract the rest-frame spectral features (the 3700-4000\AA\ Balmer break region, H$\delta$, Ca H+K, the G-band, the Mgb and Ca triplets) that are key to both characterize stellar types and to deliver a low-resolution photo-spectrum for each pixel of the sky observed. With a typical depth of AB $\sim 21.25$ mag per band, this filter set thus allows for an indiscriminate and accurate characterization of the stellar population in our Galaxy, it provides an unprecedented 2D photo-spectral information for all resolved galaxies in the local universe, as well as accurate photo-z estimates ($\Delta\,z\sim 0.01-0.03$) for moderately bright (up to $r\sim 20$ mag) extragalactic sources. While some narrow band filters are designed for the study of particular emission features ([OII]/$\lambda$3727, H$\alpha$/$\lambda$6563) up to $z < 0.015$, they also provide well-defined windows for the analysis of other emission lines at higher redshifts. As a result, J-PLUS has the potential to contribute to a wide range of fields in Astrophysics, both in the nearby universe (Milky Way, 2D IFU-like studies, stellar populations of nearby and moderate redshift galaxies, clusters of galaxies) and at high redshifts (ELGs at $z\approx 0.77, 2.2$ and $4.4$, QSOs, etc). With this paper, we release $\sim 36$ sq.deg of J-PLUS data, containing about $1.5\times 10^5$ stars and $10^5$ galaxies at $r<21$ mag., Comment: Submitted to A&A

We analyse the nature of a sample of stellar overdensities that we found projected on the Carina complex. This study is based on 2MASS photometry and involves the photometry decontamination of field stars, elaboration of intrinsic colour-magnitude diagrams J$\times$(J-Ks), colour-colour diagrams (J-H)$\times$(H-Ks) and radial density profiles, in order to determine the structure and the main astrophysical parameters of the best candidates. The verification of an overdensity as an embedded cluster requires a CMD consistent with a PMS content and MS stars, if any. From these results, we are able to verify if they are, in fact, embedded clusters. The results were, in general, rewarding: in a sample of 101 overdensities, the analysis provided 15 candidates, of which three were previously catalogued as clusters (CCCP-Cl$\,$16, Treasure Chest and FSR$\,$1555), and the 12 remaining are discoveries that provided significant results, with ages not above 4.5$\,$Myr and distances compatible with the studied complex. The resulting values for the differential reddening of most candidates were relatively high, confirming that these clusters are still (partially or fully) embedded in the surrounding gas and dust, as a rule within a shell. Histograms with the distribution of the masses, ages and distances were also produced, to give an overview of the results. We conclude that all the 12 newly found embedded clusters are related to the Carina complex., Comment: 10 pages, 14 figures, accepted for publication in MNRAS

The ESO public survey VISTA Variables in the V\'ia L\'actea (VVV) has contributed with deep multi-epoch photometry of the Galactic bulge and the adjacent part of the disk over 526 square degrees. More than a hundred cluster candidates have been reported thanks to this survey. We present the fifth article in a series of papers focused on young and massive clusters discovered in the VVV survey. In this paper, we present the physical characterization of five clusters with a spectroscopically confirmed OB-type stellar population. To characterize the clusters, we used near-infrared photometry ($J$, $H,$ and $K_S$) from the VVV survey and near-infrared $K$-band spectroscopy from ISAAC at VLT, following the methodology presented in the previous articles of the series. All clusters in our sample are very young (ages between 1-20 Myr), and their total mass are between $(1.07^{+0.40}_{-0.30})\cdot10^2$ $M_{\odot}$ and $(4.17^{+4.15}_{-2.08})\cdot10^3$ $M_{\odot}$. We observed a relation between the clusters total mass $M_{ecl}$ and the mass of their most massive stellar member $m_{max}$, even for clusters with an age $<$ 10 Myr., Comment: Accepted for publication, A&A

Throughout the last decade sensitive infrared observations obtained by the Spitzer Space Telescope significantly increased the known population of YSOs associated with nearby molecular clouds. With such a census recent studies have characterized pre-main sequence stars (PMS) and determined parame- ters from different wavelengths. Given the restricted Spitzer coverage of some of these clouds, relative to their extended regions, these YSO populations may represent a limited view of star formation in these regions. We are taking advantage of mid-infrared observations from the NASA Wide Field Infrared Survey Explorer (WISE), which provides an all sky view and therefore full coverage of the nearby clouds, to assess the degree to which their currently known YSO population may be representative of a more complete population. We extend the well established classification method of the Spitzer Legacy teams to archived WISE observations. We have adopted 2MASS photometry as a standard catalogue for comparisons. Besides the massive embedded cluster IC5146 we provide a multiband view of five new embedded clusters in its surroundings that we discovered with WISE. In short, the analysis in- volves the following for the presently studied cluster sample: (1) extraction of 2MASS/WISE/Spitzer photometry in a wide circular region; (2) field-star decontamination to enhance the intrinsic Colour-magnitude diagram (CMD) morphology (essential for a proper derivation of reddening, age, and distance from the Sun); and (3) construction of Colour-magnitude filters, for more contrasted stellar radial density profiles (RDPs)., Comment: arXiv admin note: text overlap with arXiv:astro-ph/0306595, arXiv:astro-ph/0406003 by other authors

We report our study of features at the observed red end of the white dwarf cooling sequences for three Galactic globular clusters: NGC\,6397, 47\,Tucanae and M\,4. We use deep colour-magnitude diagrams constructed from archival Hubble Space Telescope (ACS) to systematically investigate the blue turn at faint magnitudes and the age determinations for each cluster. We find that the age difference between NGC\,6397 and 47\,Tuc is 1.98$^{+0.44}_{-0.26}$\,Gyr, consistent with the picture that metal-rich halo clusters were formed later than metal-poor halo clusters. We self-consistently include the effect of metallicity on the progenitor age and the initial-to-final mass relation. In contrast with previous investigations that invoked a single white dwarf mass for each cluster, the data shows a spread of white dwarf masses that better reproduce the shape and location of the blue turn. This effect alone, however, does not completely reproduce the observational data - the blue turn retains some mystery. In this context, we discuss several other potential problems in the models. These include possible partial mixing of H and He in the atmosphere of white dwarf stars, the lack of a good physical description of the collision-induced absorption process and uncertainties in the opacities at low temperatures. The latter are already known to be significant in the description of the cool main sequence. Additionally, we find that the present day local mass function of NGC\,6397 is consistent with a top-heavy type, while 47\,Tuc presents a bottom-heavy profile., Comment: Accepted for publication in MNRAS (16 pages, 19 figures)

Context The ESO Public Survey VISTA Variables in the V\'ia L\'actea (VVV) provides deep multi-epoch infrared observations for an unprecedented 562 sq. degrees of the Galactic bulge and adjacent regions of the disk. Nearly 150 new open clusters and cluster candidates have been discovered in this survey. Aims We present the fourth article in a series of papers focussed on young and massive clusters discovered in the VVV survey. This article is dedicated to the cluster VVV CL041, which contains a new very massive star candidate, WR 62-2. Methods Following the methodology presented in the first paper of the series, wide-field, deep JHKs VVV observations, combined with new infrared spectroscopy, are employed to constrain fundamental parameters (distance, reddening, mass, age) of VVV CL041. Results We confirm that the cluster VVV CL041 is a young (less than 4 Myrs) and massive (3 +/- 2 x 10^3 Msol) cluster, and not a simple asterism. It is located at a distance of 4.2 +/- 0.9 kpc, and its reddening is A_V = 8.0 +/- 0.2 mag, which is slightly lower than the average for the young clusters towards the centre of the Galaxy. Spectral analysis shows that the most luminous star of the cluster, of the WN8h spectral type, is a candidate to have an initial mass larger than 100 Msol., Comment: 8 pages, 7 figures, 2 tables, Accepted to A&A

We obtained SOAR telescope B and V photometry of 14 star clusters and 2 associations in the Bridge tidal structure connecting the LMC and SMC. These objects are used to study the formation and evolution of star clusters and associations under tidal stresses from the Clouds. Typical star clusters in the Bridge are not richly populated and have in general relatively large diameters (~30-35 pc), being larger than Galactic counterparts of similar age. Ages and other fundamental parameters are determined with field-star decontaminated photometry. A self-consistent approach is used to derive parameters for the most-populated sample cluster NGC 796 and two young CMD templates built with the remaining Bridge clusters. We find that the clusters are not coeval in the Bridge. They range from approximately a few Myr (still related to optical HII regions and WISE and Spitzer dust emission measurements) to about 100-200 Myr. The derived distance moduli for the Bridge objects suggests that the Bridge is a structure connecting the LMC far-side in the East to the foreground of the SMC to the West. Most of the present clusters are part of the tidal dwarf candidate D 1, which is associated with an H I overdensity. We find further evidence that the studied part of the Bridge is evolving into a tidal dwarf galaxy, decoupling from the Bridge., Comment: 15 pages, 15 figures, MNRAS, Accepted 2015 July 27

We investigate interaction effects on the dynamics and morphology of the galaxy pairs AM\,2058-381 and AM\,1228-260. This work is based on $r'$ images and long-slit spectra obtained with the Gemini Multi-Object Spectrograph at the Gemini South Telescope. The luminosity ratio between the main (AM\,2058A) and secondary (AM\,2058B) components of the first pair is a factor of $\sim$ 5, while for the other pair, the main (AM\,1228A) component is 20 times more luminous than the secondary (AM\,1228B). The four galaxies have pseudo-bulges, with a S\'ersic index $n<2$. Their observed radial velocities profiles (RVPs) present several irregularities. The receding side of the RVP of AM\,2058A is displaced with respect to the velocity field model, while there is a strong evidence that AM\,2058B is a tumbling body, rotating along its major axis. The RVPs for AM\,1228A indicate a misalignment between the kinematic and photometric major axes. The RVP for AM\,1228B is quite perturbed, very likely due to the interaction with AM\,1228A. NFW halo parameters for AM\,2058A are similar to those of the Milky Way and M\,31. The halo mass of AM\,1228A is roughly 10\% that of AM\,2058A. The mass-to-light (M/L) of AM\,2058 agrees with the mean value derived for late-type spirals, while the low M/L for AM\,1228A may be due to the intense star formation ongoing in this galaxy., Comment: 20 pages, 10 figures, accepted for publication in MNRAS

We present a simple approach for obtaining robust values of astrophysical parameters from the observed colour-magnitude diagrams (CMDs) of star clusters. The basic inputs are the Hess diagram built with the photometric measurements of a star cluster and a set of isochrones covering wide ranges of age and metallicity. In short, each isochrone is shifted in apparent distance modulus and colour excess until it crosses over the maximum possible Hess density. Repeating this step for all available isochrones leads to the construction of the solution map, in which the optimum values of age and metallicity - as well as foreground/background reddening and distance from the Sun - can be searched for. Controlled tests with simulated CMDs show that the approach is efficient in recovering the input values. We apply the approach to the open clusters M\,67, NGC\,6791, and NGC\,2635, which are characterised by different ages, metallicities and distances from the Sun., Comment: Accepted by MNRAS

We employed field star decontaminated 2MASS photometry to study four nearby optical embedded clusters -- Collinder34, NGC3293, NGC3766 and NGC6231 -- obtaining deep colour-magnitude diagrams and stellar radial density profiles. We found what seems to be pre-main sequences detached in different amounts from main sequences in these diagrams. The structural analysis of each cluster revealed different radial distributions for these two sequences. We argued that the detached evolutionary sequences in our sample may be evidence of sequential star formation. Finally, we compared the sample cluster parameters with those of other young clusters in the literature and point out evidence that NGC3766 and NGC6231 might be evolving to OB associations., Comment: 19 pages, 17 figures and 7 tables

In this study, we present a detailed study of mass segregation in the globular clister NGC 6397. First, we carry out a photometric analysis of projected ESO-VLT data (between 1 and 10 arcmin from the cluster centre), presenting the luminosity function corrected by completeness. The luminosity function shows a higher density of bright stars near the central region of the data, with respect to the outer region. We calculate a deprojected model (covering the whole cluster) estimating a total number of stars of 193000 +- 19000. The shapes of the surface brightness and density-number profiles versus the radial coordinate r (instead of the projected coordinate R) lead to a decreasing luminosity for an average star, and thus of mass, up to 1 arcmin, quantifying the mass segregation. The deprojected model does not show evidence of mass segregation outside this region.

We report the discovery of two new variable stars in the metal-poor globular cluster NGC 288, found by means of time-series CCD photometry. We classified the new variables as SX Phoenicis due to their characteristic fundamental mode periods (1.02 +- 0.01 and 0.69 +- 0.01 hours), and refine the period estimates for other six known variables. SX Phe stars are known to follow a well-defined Period-Luminosity (P-L) relation and, thus, can be used for determining distances; they are more numerous than RR Lyraes in NGC~288. We obtain the P-L relation for the fundamental mode M_V = (-2.59 +- 0.18) log P_0(d) + (-0.34 +- 0.24) and for the first-overtone mode M_V = (-2.59 +- 0.18) log P_1(d) + (0.50 +- 0.25). Multi-chromatic isochrone fits to our UBV color-magnitude diagrams, based on the Dartmouth Stellar Evolution Database, provide <[Fe/H]> = -1.3 +- 0.1, E(B-V) = 0.02 +- 0.01 and absolute distance modulus (m-M)0 = 14.72 +- 0.01 for NGC 288., Comment: 8 pages, 9 figures, 3 tables

VISTA Variables in the V\'ia L\'actea (VVV) is one of six ESO Public Surveys using the 4 meter Visible and Infrared Survey Telescope for Astronomy (VISTA). The VVV survey covers the Milky Way bulge and an adjacent section of the disk, and one of the principal objectives is to search for new star clusters within previously unreachable obscured parts of the Galaxy. The primary motivation behind this work is to discover and analyze obscured star clusters in the direction of the inner Galactic disk and bulge. Regions of the inner disk and bulge covered by the VVV survey were visually inspected using composite JHKs color images to select new cluster candidates on the basis of apparent overdensities. DR1, DR2, CASU, and PSF photometry of 10x10 arcmin fields centered on each candidate cluster were used to construct color-magnitude and color-color diagrams. Follow-up spectroscopy of the brightest members of several cluster candidates was obtained in order to clarify their nature. We report the discovery of 58 new infrared cluster candidates. Fundamental parameters such as age, distance, and metallicity were determined for 20 of the most populous clusters., Comment: 23 pages, 20 figures and 3 tables

NGC 6357 is an active star-forming region located in the Sagittarius arm displaying several star clusters, which makes it a very interesting target to investigate star formation and early cluster evolution. We explore NGC 6357 with the "VISTA Variables in the V\'ia a L\'actea" (VVV) photometry of seven embedded clusters (ECs), and one open cluster (OC) projected in the outskirts of the complex.Photometric and structural properties (age, reddening, distance, core and total radii) of the star clusters are derived. VVV saturated stars are replaced by their 2MASS counterparts. Field-decontaminated VVV photometry is used to analyse Colour-Magnitude Diagrams (CMDs), stellar radial density profiles (RDPs) and determine astrophysical parameters. We report the discovery of four ECs and one intermediate-age cluster in the complex area. We derive a revised distance estimate for NGC 6357 of 1.78$\pm$0.1 kpc based on the cluster CMD morphologies. Among the ECs, one contains the binary star the WR 93, while the remaining ones are dominated by pre-main sequence (PMS) stars, young-stellar objects (YSO) and/or and have a developed main sequence. These features reflect a significant age spread among the clusters. Evidence is found that the relatively populous cluster Pismis 24 hosts two subclusters., Comment: This article will be published in the A&A. 11 pages, 15 figures and 3 tables

Andrews-Lindsay 1 is a pertinent open cluster granted it may host the planetary nebula PHR 1315-6555, yet ambiguities linger concerning its fundamental parameters (>50% scatter). New multiband BVJHW(1-4) photometry for cluster and field stars, in concert with observations of recently discovered classical Cepheids, were used to constrain the reddening and velocity-distance profiles along the sight-line. That analysis yielded the following parameters for the cluster: E(J-H)=0.24+-0.03, d=10.0+-0.4 kpc (d(JH)=9.9+-0.6 kpc, d(BV)=10.1+-0.5 kpc), and log(t)=8.90+-0.15. The steep velocity-distance gradient along l~305 indicates that two remote objects sharing spatial and kinematic parameters (i.e., PHR 1315-6555 and Andrews-Lindsay 1) are associated, thus confirming claims that the PN is a cluster member (e.g., Parker et al.). The new distance for PHR 1315-6555 is among the most precise yet established for a Galactic PN (err_d=4%)., Comment: To appear in Astronomy and Astrophysics

Context: Young massive clusters are key to map the Milky Way's structure, and near-IR large area sky surveys have contributed strongly to the discovery of new obscured massive stellar clusters. Aims: We present the third article in a series of papers focused on young and massive clusters discovered in the VVV survey. This article is dedicated to the physical characterization of VVV CL086, using part of its OB-stellar population. Methods: We physically characterized the cluster using $JHK_S$ near-infrared photometry from ESO public survey VVV images, using the VVV-SkZ pipeline, and near-infrared $K$-band spectroscopy, following the methodology presented in the first article of the series. Results: Individual distances for two observed stars indicate that the cluster is located at the far edge of the Galactic bar. These stars, which are probable cluster members from the statistically field-star decontaminated CMD, have spectral types between O9 and B0V. According to our analysis, this young cluster ($1.0$ Myr $<$ age $< 5.0$ Myr) is located at a distance of $11^{+5}_{-6}$ kpc, and we estimate a lower limit for the cluster total mass of $(2.8^{+1.6}_{-1.4})\cdot10^3 {M}_{\odot}$. It is likely that the cluster contains even earlier and more massive stars., Comment: Accepted for publication as a Letter in A&A

New and existing X-ray, UBVJHKsW(1-4), and spectroscopic observations were analyzed to constrain fundamental parameters for M25, NGC 7790, and dust along their sight-lines. The star clusters are of particular importance given they host the classical Cepheids U Sgr, CF Cas, and the visual binary Cepheids CEa and CEb Cas. Precise results from the multiband analysis, in tandem with a comprehensive determination of the Cepheids' period evolution (dP/dt) from ~140 years of observations, helped resolve concerns raised regarding the clusters and their key Cepheid constituents. Specifically, distances derived for members of M25 and NGC 7790 are 630+-25 pc and 3.40+-0.15 kpc, respectively., Comment: To appear in Astronomy and Astrophysics

We present an observational study of the interaction effect on the dynamics and morphology of the minor merger AM1219-430. This work is based on r' and g' images and long-slit spectra obtained with the Gemini Multi-Object Spectrograph at the Gemini South Telescope. We detected a tidal tail in the main galaxy (AM1219A) and a bridge of material connecting the galaxies. In luminosity, AM1219A is about 3.8 times brighter than the secondary (AM1219B). The surface brightness profile of AM1219A was decomposed into bulge and disc components. The profile shows a light excess of ~ 53 % due to the contribution of star-forming regions, which is typical of starburst galaxies. On the other hand, the surface brightness profile of AM1219B shows a lens structure in addition to the bulge and disc. The scale lengths and central magnitudes of the disc structure of both galaxies agree with the average values derived for galaxies with no sign of ongoing interaction or disturbed morphology. The S\'ersic index (n<2), the effective and scale radii of the bulge of both galaxies are typical of pseudo-bulges. The rotation curve of AM1219A derived from the emission line of ionized gas is quite asymmetric, suggesting a gas perturbed by interaction. We explore all possible values of stellar and dark matter masses. The overall best-fitting solution for the mass distribution of AM1219A was found with M/L for bulge and disc of M/L_b=2.8_-0.4^+0.4 and M/L_d=2.4_-0.2^+0.3, respectively, and a Navarro, Frenk and White profile of M_200=2.0_-0.4^+0.5 x10^12 M_sun and c=16.0_-1.1^+1.2. The estimated dynamical mass is 1.6x10^11 M_sun, within a radius of ~ 10.6 kpc., Comment: 13 pages, 11 figures

We present multichromatic isochrone fits to the colour-magnitude data of the globular cluster NGC 6366, based on Hubble Space Telescope Advanced Camera for Surveys/Wide Field Channel and Southern Astrophysical Research photometric data. We corrected the photometric data for differential reddening and calculated the mean ridge line of the colour-magnitude diagrams. We compared the isochrones of Dartmouth Stellar Evolution Database and PAdova and TRieste Stellar Evolution Code both with microscopic diffusion starting on the main sequence. Bracketing all previous determinations of this cluster, we tested metallicities from [Fe/H]=-1.00 to [Fe/H]=-0.50, and ages from 9 to 13 Gyr. After determining the total to selective extinction ratio only from stars belonging to this cluster, R_V=3.06+/-0.14, we found the parameters for this cluster to be E(B-V)=0.69+/-0.02(int)+/-0.04(ext), (m-M)_V=15.02+/-0.07(int)+/-0.13(ext), Age=11+/-1.15 Gyr. Evolutionary models fail to reproduce the low-Teff sequence in multiband colour-magnitude diagrams, indicating that they still have an incomplete physics. We found that the Dartmouth Stellar Evolution Database isochrones better fit the subgiant branch and low main sequence than the PAdova and TRieste Stellar Evolution Code., Comment: 9 pages, 5 figures

Cepheids are key to establishing the cosmic distance scale. Therefore it's important to assess the viability of QZ Nor, V340 Nor, and GU Nor as calibrators for Leavitt's law via their purported membership in the open cluster NGC 6067. The following suite of evidence confirms that QZ Nor and V340 Nor are members of NGC 6067, whereas GU Nor likely lies in the foreground: (i) existing radial velocities for QZ Nor and V340 Nor agree with that established for the cluster (-39.4+-1.2 km/s) to within 1 km/s, whereas GU Nor exhibits a markedly smaller value; (ii) a steep velocity-distance gradient characterizes the sight-line toward NGC 6067, thus implying that objects sharing common velocities are nearly equidistant; (iii) a radial profile constructed for NGC 6067 indicates that QZ Nor is within the cluster bounds, despite being 20' from the cluster center; (iv) new BVJH photometry for NGC 6067 confirms the cluster lies d=1.75+-0.10 kpc distant, a result that matches Wesenheit distances computed for QZ Nor/V340 Nor using the Benedict et al. (2007, HST parallaxes) calibration. QZ Nor is a cluster Cepheid that should be employed as a calibrator for the cosmic distance scale., Comment: To appear in ApSS

We present panchromatic isochrone fits to the color magnitude data of the globular cluster NGC 6366, based on HST ACS/WFC and SOAR photometric data. Before performing the isochrone fits, we corrected the photometric data for differential reddening and calculated the mean ridge line of the color magnitude diagrams. We compared the isochrones of Dartmouth Stellar Evolution Database and PAdova and TRieste Stellar Evolution Code (with microscopic diffusion starting on the main sequence). Based on previous determinations of the metallicity of this cluster we test it from [Fe/H]=-1.00 to [Fe/H]= -0.50, and the age from 9 to 13 Gyrs. The uncertainties do not decrease when we fit simultaneous colors. We also find that the Dartmouth Stellar Evolution Database isochrones have a better fit in the sub giant branch and low main sequence than the PAdova and TRieste Stellar Evolution Code. Considering the most recent spectroscopic determination of the metallicity ([Fe/H]= -0.67), we find E(B-V)=0.69+/-0.02, (m-M)_V=15.02+/-0.07 and 11+/-2 Gyr for NGC 6366., Comment: 4 pages, 2 figures. Proceedings of the conference "Reading the book of globular clusters with the lens of stellar evolution", to be published in Memorie della Societ\'a Astronomica Italiana

We study the kinematics and excitation mechanisms of H2 and [Fe II] lines in a sample of 67 emission-line galaxies with Infrared Telescope Facility SpeX near-infrared (NIR, 0.8-2.4 micrometers) spectroscopy together with new photoionisation models. H2 emission lines are systematically narrower than narrow-line region (NLR) lines, suggesting that the two are, very likely, kinematically disconnected. The new models and emission-line ratios show that the thermal excitation plays an important role not only in active galactic nuclei but also in star forming galaxies. The importance of the thermal excitation in star forming galaxies may be associated with the presence of supernova remnants close to the region emitting H2 lines. This hypothesis is further supported by the similarity between the vibrational and rotational temperatures of H2. We confirm that the diagram involving the line ratios H2 2.121/Br_gamma and [Fe II] 1.257/Pa_beta is an efficient tool for separating emission-line objects according to their dominant type of activity. We suggest new limits to the line ratios in order to discriminate between the different types of nuclear activity., Comment: Accepted for publication in MNRAS

Context: The ESO Public Survey "VISTA Variables in the V\'ia L\'actea" (VVV) provides deep multi-epoch infrared observations for an unprecedented 562 sq. degrees of the Galactic bulge, and adjacent regions of the disk. In this survey nearly 150 new open clusters and cluster candidates have been discovered. Aims: This is the second in a series of papers about young, massive open clusters observed using the VVV survey. We present the first study of six recently discovered clusters. These clusters contain at least one newly discovered Wolf-Rayet (WR) star. Methods: Following the methodology presented in the first paper of the series, wide-field, deep JHKs VVV observations, combined with new infrared spectroscopy, are employed to constrain fundamental parameters for a subset of clusters. Results: We affirm that the six studied stellar groups are real young (2-7 Myr) and massive (between 0.8 and 2.2 10^3 Msol) clusters. They are highly obscured (Av ~ 5-24 mag) and compact (1-2 pc). In addition to WR stars, two of the six clusters also contain at least one red supergiant star. We claim the discovery of 8 new WR stars, and 3 stars showing WR-like emission lines which could be classified WR or OIf. Preliminary analysis provides initial masses of ~30-50 Msol for the WR stars. Finally,we discuss the spiral structure of the Galaxy using as tracers the six new clusters together with the previously studied VVV clusters., Comment: 17 pages, 8 figurs, accepted in A&A

Context: The ESO Public Survey "VISTA Variables in the V\'ia L\'actea" (VVV) provides deep multi-epoch infrared observations for an unprecedented 562 sq. degrees of the Galactic bulge, and adjacent regions of the disk. Aims: The VVV observations will foster the construction of a sample of Galactic star clusters with reliable and homogeneously derived physical parameters (e.g., age, distance, and mass, etc.). In this first paper in a series, the methodology employed to establish cluster parameters for the envisioned database are elaborated upon by analyzing a subsample of 4 known young open clusters: Danks 1, Danks 2, RCW 79, and DBS 132. The analysis offers a first glimpse of the information that can be gleaned for the final cluster database from the VVV observations. Methods: Wide-field, deep JHKs VVV observations, combined with new infrared spectroscopy, are employed to constrain fundamental parameters for a subset of clusters. Results: Results inferred from the deep near-infrared photometry which features mitigated uncertainties (e.g. the accuracy of the photometry is better than 0.1mag for Ks<18mag), the wide field-of-view of the VVV survey, and numerous high quality low resolution spectra (typically more than 10 per cluster), are used to establish independent cluster parameters which enable existing determinations to be assessed. An anomalous reddening law in the direction toward the Danks' clusters is found, i.e. E(J-H)/E(H-Ks)=2.20+/-0.06, which exceeds published values for the inner Galaxy. The G305 star forming complex, which includes the Danks' clusters, lies beyond the Sagittarius-Carina spiral arm and occupies the Centaurus arm. Finally, the first deep infrared color-magnitude diagram of RCW 79 is presented which reveal a sizable pre-main sequence population. A list of candidate variable stars in G305 region is reported., Comment: 18 pages, 13 figures, 4 tables, 3 tables in the online material, photometric Catalogs to be published soon. Accepted in A&A

We derive astrophysical and structural parameters of the poorly studied open clusters NGC 6866, NGC 7062, and NGC 2360 based on filtered 2MASS (J, J -H) diagrams, and stellar radial density profiles. The field star decontamination technique is utilised for selecting high-probability cluster members. The E(B -V) reddening values of the three clusters derived from 2MASS JHKs agree with those inferred from UBV and uvby-{\beta} photometries. We find that the core mass function slopes are flatter than the halo's for the three clusters. The large core and cluster radii of NGC 6866 and NGC 2360 indicate an expanded core, which may suggest the presence of stellar mass black-holes. NGC 2360 is located in the third quadrant (l = 229.80), where Giant Molecular Clouds are scarce that, together with its relatively large mass (~ 1800 msun), might explain its longevity(~ 1.8Gyr) in the Galaxy., Comment: 26 pages, 6 tables, 15 figures, accepted for New Astronomy

It is currently widely accepted that open star clusters and stellar associations result from the evolution of embedded star clusters. Parameters such star formation efficiency, time-scale of gas removal and velocity dispersion can be determinants of their future as bound or unbound systems. Finding objects at an intermediate evolution state can provide constraints to model the embedded cluster evolution. In the HII region IC1396, Trumpler 37 is an extended young cluster that presents characteristics of an association. We employed the Two Micron All Sky Survey (2MASS) photometry to analysing its structure and stellar content, and determining its astrophysical parameters. We also analysed 11 bright-rimmed clouds in IC1396 in order to search for young infrared star clusters, and the background open star cluster Teutsch 74, to verify whether it has any contribution to the observed stellar density profile of Trumpler 37. The derived parameters and comparison with template objects from other studies lead us to conclude that Trumpler 37, rather than as a star cluster, will probably emerge from its molecular cloud as an OB association., Comment: 13 pages, 10 figures, 6 tables

Approximately 14% of known Galactic open clusters possess absolute errors 20% as evaluated from n>3 independent distance estimates, and the statistics for age estimates are markedly worse. That impedes such diverse efforts as calibrating standard candles and constraining masses for substellar companions. New data from the VVV survey may be employed to establish precise cluster distances with comparatively reduced uncertainties (<10%). This is illustrated by deriving parameters for Pismis 19 and NGC 4349, two pertinent open clusters which hitherto feature sizable uncertainties (60%). Fundamental parameters determined for Pismis 19 from new VVV JHKs photometry are d=2.40+-0.15 kpc, =0.34+-0.04, and log(t)=9.05+-0.10, whereas for NGC 4349 the analysis yielded d=1.63+-0.13 kpc, E(J-H)=0.09+-0.02, log(t)=8.55+-0.10. The results exhibit a significant (>5x) reduction in uncertainties, and indicate that: i) existing parameters for the substellar object NGC 4349 127b require revision, in part because the new cluster parameters imply that the host is 20% less-massive (M*/Ms~3.1); ii) R Cru is not a member of NGC 4349 and should be excluded from period-Wesenheit calibrations that anchor the distance scale; iii) and results for Pismis 19 underscore the advantages gleaned from employing deep VVV JHKs data to examine obscured (Av~4) and differentially reddened intermediate-age clusters., Comment: To appear in A&A Letters

The ESO Public Survey VISTA Variables in the Via Lactea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for ~5 years. In this paper we describe the progress of the survey observations in the first observing season, the observing strategy and quality of the data obtained. The observations are carried out on the 4-m VISTA telescope in the ZYJHKs filters. In addition to the multi-band imaging the variability monitoring campaign in the Ks filter has started. Data reduction is carried out using the pipeline at the Cambridge Astronomical Survey Unit. The photometric and astrometric calibration is performed via the numerous 2MASS sources observed in each pointing. The first data release contains the aperture photometry and astrometric catalogues for 348 individual pointings in the ZYJHKs filters taken in the 2010 observing season. The typical image quality is ~0.9-1.0". The stringent photometric and image quality requirements of the survey are satisfied in 100% of the JHKs images in the disk area and 90% of the JHKs images in the bulge area. The completeness in the Z and Y images is 84% in the disk, and 40% in the bulge. The first season catalogues contain 1.28x10^8 stellar sources in the bulge and 1.68x10^8 in the disk area detected in at least one of the photometric bands. The combined, multi-band catalogues contain more than 1.63x10^8 stellar sources. About 10% of these are double detections due to overlapping adjacent pointings. These overlapping multiple detections are used to characterise the quality of the data. The images in the JHKs bands extend typically ~4 mag deeper than 2MASS. The magnitude limit and photometric quality depend strongly on crowding in the inner Galactic regions. The astrometry for Ks=15-18 mag has rms ~35-175 mas., Comment: Accepted for publication in Astronomy and Astrophysics (Section 14: Catalogs and data)

We investigate the nature of 14 embedded clusters (ECs) related to a group of four H II regions Sh2-235, Sh2-233, Sh2-232, and Sh2-231 in the giant molecular cloud G174 + 2.5. Projected towards the Galactic anticentre, these objects are a possible example of the collect and collapse scenario. We derive astrophysical parameters (age, reddening, distance, core and cluster radii) for the ECs and investigate the relationship among their parameters. Parameters are derived with field decontaminated 2MASS colour-magnitude diagrams (CMDs) and stellar radial density profiles (RDPs). The CMDs of these young clusters are characterised by a poorly-populated main sequence and a significant number of pre-main sequence stars, affected by differential reddening. The ECs are KKC 11, FSR 784, Sh2-235 E2, Sh2-235 Cluster, Sh2-233SE Cluster, BDSB 73, Sh2-235B Cluster, BDSB 72, BDSB 71, Sh2-232 IR, PCS 2, and the newly found clusters CBB 1 and CBB 2. We were able to derive fundamental parameters for all ECs in the sample. Structural parameters are derived for FSR 784, Sh2-235 Cluster and Sh2-235E2., Comment: 14 pages and 15 figures; MNRAS 2011

Vista Variables in the Via Lactea (VVV) is an ESO Public Survey that is performing a variability survey of the Galactic bulge and part of the inner disk using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA). The survey covers 520 deg^2 of sky area in the ZYJHK_S filters, for a total observing time of 1929 hours, including ~ 10^9 point sources and an estimated ~ 10^6 variable stars. Here we describe the current status of the VVV Survey, in addition to a variety of new results based on VVV data, including light curves for variable stars, newly discovered globular clusters, open clusters, and associations. A set of reddening-free indices based on the ZYJHK_S system is also introduced. Finally, we provide an overview of the VVV Templates Project, whose main goal is to derive well-defined light curve templates in the near-IR, for the automated classification of VVV light curves., Comment: 25 pages, 18 figures. To appear in the Carnegie Observatories Astrophysics Series, Volume 5

We present SOAR/OSIRIS cross-dispersed NIR integrated spectra of 12 Galactic globular clusters that are employed to test Maraston (2005, M05) NIR EPS models, and to provide spectral observational constraints to calibrate future models. We measured Ew of the most prominent NIR absorption features. Optical Ew were also measured. The globular clusters Ew were compared with model predictions with ages within 4-15 Gyr, and metallicities between 1/200 and 2 Zsun. Observed integrated colours were also compared with models. The NIR integrated spectra among our sample appear qualitatively similar in most the absorption features. The M05 models can properly predict the optical Ew observed in globular clusters. Regarding the NIR, they do underestimate the strength of Mg I 1.49mum, but they can reproduce the observed Ew of Fe I 1.58mum, Si I 1.59mum, and CO 2.29mum, in about half of our sample. The remaining objects require the inclusion of intermediate-age populations. Thus, we suggest that the presence of C- and O-rich stars in models is important to reproduce the observed strengths of metallic lines. Another possibility is the lack of alpha-enhancement in the models. In the case of the optical and NIR Fe I lines, standard models and those that include blue horizontal branch stars, produce similar results. A similar trend is observed for Na I 5895A, while in the case of the G-band, the models with blue horizontal branch do describe better the observations. For most of the sample the optical to NIR colours are well described by the M05 models. In general, M05 models can provide reliable information on the NIR stellar population of galaxies, but only when Ew and colours are taken together, in other words, Ew and continuum fluxes should be simultaneously fitted. However, the results should be taken with caution, since the models tend to predict results biased towards young ages., Comment: 11 pages, 10 Figures, Accepted by MNRAS

Embedded clusters are formed in molecular clouds where massive stars can produce HII regions. The detailed embedded-open cluster evolutionary connection as well as the origin of associations are yet to be unveiled. There appears to be a high infant mortality rate among embedded clusters and the few survivors evolve to open clusters. We study the colour-magnitude diagrams and structure of the star clusters related to the Sh2-132 HII region using the 2MASS database. Cluster fundamental and structural parameters are determined via MS and PMS isochrones and stellar radial density profiles. We report the discovery of four clusters. One of them is projected a few diameters away from the optical cluster Teutsch\,127 and appears to be deeply embedded, seen only in the infrared. Evidence is found that we are witnessing the dynamical transition from an embedded to an open cluster. An additional cluster is also close to Teutsch\,127 and might be associated with a bow-shock. We also study the CMD and structure of the open cluster Berkeley\,94 in Sh2-132 and a new cluster which is projected in the outskirts of the complex. Finally, we searched for star clusters around the two known Wolf-Rayet stars in the complex. One of them appears to be related to a compact cluster. Finally, the present analyses suggest early dynamical evolution for young star clusters., Comment: 12 pages, 20 figures, 6 tables

We employ IRTF SpeX NIR (0.8--2.4mu m) spectra to investigate the stellar population (SP), active galactic nuclei (AGN), featureless continuum (FC) and hot dust properties in 9 Sy1 and 15 Sy2 galaxies. Both the {\sc starlight} code and the hot dust as an additional base element were used for the first time in this spectral range. Our synthesis shows significant differences between Sy1 and Sy2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy1 galaxies, and only of ~25% of the Sy2; about 50% of the Sy2 galaxies require an FC component contribution >20%; this fraction increases to about 60% in the Sy1. In about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Our SP synthesis confirms that the 1.1microns CN band can be used as a tracer of intermediate-age stellar populations., Comment: To appear in IAU S262 proceedings, 4 pages, 4 figures

We employ IRTF SpeX NIR (0.8-2.4 microns) spectra to investigate the stellar population (SP), active galactic nuclei (AGN) featureless continuum (FC) and hot dust properties in 9 Sy 1 and 15 Sy 2 galaxies. Both the starlight code and the hot dust as an additional base element were used for the first time in this spectral range. We found evidence of correlation among the equivalent widths (W) Si I 1.59 microns x Mg I 1.58 microns, equally for both kinds of activity. Part of the W{Na I 2.21 microns} and W {CO 2.3 microns} strengths may be related to galaxy inclination. Our synthesis shows significant differences between Sy 1 and Sy 2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2; about 50 % of the Sy 2 galaxies require a $FC$ component contribution >20%, while this fraction increases to 60% in the Sy 1; also, in about 50 % of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Our SP synthesis confirms that the 1.1 micron CN band can be used as a tracer of intermediate-age SPs. The simultaneous fitting of SP, FC and hot dust components increased in ~150% the number of AGNs with hot dust detected and the mass estimated. The NIR emerges as an excellent window to study the stellar population of Sy 1 galaxies, as opposed to the usually heavily attenuated optical range. Our approach opens a new way to investigate and quantify the individual contribution of the three most important NIR continuum components observed in AGNs., Comment: The paper contains 14 figures and 5 tables. Accepted for publication in MNRAS

We present photometry for the globular cluster NGC 6642 using the F606W and F814W filters with the ACS/WFC third generation camera on board of Hubble Space Telescope. The Colour Magnitude Diagram shows sources reaching ~ 6 mags below the turn-off in m_F606W. A theoretical isochrone fitting was performed and evolutionary parameters were obtained, such as the metallicity [Fe/H] = -1.80 +/- 0.2 and age log(Age) = 10.14 +/- 0.05. We confirm that NGC 6642 is located in the Galactic bulge, with a distance to the Sun d_{\odot} = 8.05 +/- 0.66 ~ kpc$ and the reddening E(B-V) = 0.46 +/- 0.02. These values are in general agreement with those of previous authors. About 30 blue stragglers were found within the central 1.6 pc of NGC 6642. They are strongly concentrated to the very central regions. The cluster displays a well-developed horizontal branch, with a much redder morphology than that of typical old halo globular clusters of similar metallicity. Completeness corrected luminosity and mass functions were obtained for different annuli centred on NGC 6642. Their spatial variation indicates the existence of mass segregation and depletion of low mass stars. Most striking is the inverted shape of the mass function itself, with an increase in number as a function of increasing mass. This has been previously observed in other globular clusters and is also the result of N-body simulations of stellar systems which have undergone ~ 90% of their lifetime and which are subjected to strong tidal effects. We also analysed the density profile and concluded that NGC 6642 has a collapsed core, provided completeness effects are correctly accounted for. We thus conclude from independent means that NGC 6642 is a very old, highly-evolved, core-collapsed globular cluster with an atypical HB morphology., Comment: Paper, contains 8 figures, 1 table and 8 pages

We employ the recently installed near infrared Multi-Conjugate Adaptive optics demonstrator (MAD) to determine basic properties of a newly identified, old and distant, Galactic open cluster (FSR1415). The MAD facility remarkably approaches the diffraction limit, reaching a resolution of 0.07 arcsec (in K), that is also uniform in a field of ~1.8 arcmin in diameter. The MAD facility provides photometry that is 50% complete at K~19. This corresponds to about ~2.5 mag below the cluster main sequence turn-off. This high quality data set allows us to derive an accurate heliocentric distance of ~8.6 kpc, a metallicity close to solar, and an age of ~2.5 Gyr. On the other hand, the deepness of the data allow us to reconstruct (completeness-corrected) mass functions indicating a relatively massive cluster, with a flat core MF. The VLT/MAD capabilities will therefore provide fundamental data in identifying/analyzing other faint and distant open clusters in the Galaxy III and IV quadrants., Comment: Accepted for publication in MNRAS

We derive fundamental parameters of the embedded cluster DBSB48 in the southern nebula Hoffleit18 and the very young open cluster Trumpler14, by means of deep JHKs infrared photometry. We build colour-magnitude and colour-colour diagrams to derive reddening and age, based on main sequence and pre-main sequence distributions. Radial stellar density profiles are used to study cluster structure and guide photometric diagram extractions. Field-star decontamination is applied to uncover the intrinsic cluster sequences in the diagrams. Ages are inferred from K-excess fractions. A prominent pre-main-sequence population is present in DBSB48, and the K-excess fraction f_K=55+/-6% gives an age of 1.1+/-0.5Myr. A mean reddening of A_K_s=0.9+/-0.03 was found, corresponding to $A_V=8.2\pm0.3$. The cluster CMD is consistent with the far kinematic distance of 5 kpc for Hoffleit 18. For Trumpler 14 we derived similar parameters as in previous studies in the optical, in particular an age of $1.7\pm0.7$ Myr. The fraction of stars with infrared excess in Trumpler 14 is $f_K=28\pm4%$. Despite the young ages, both clusters are described by a King profile with core radii $\rc=0.46\pm0.05$ pc and $\rc=0.35\pm0.04$ pc, respectively for DBSB 48 and Trumpler 14. Such cores are smaller than those of typical open clusters. Small cores are probably related to the cluster formation and/or parent molecular cloud fragmentation. In DBSB 48, the magnitude extent of the upper main sequence is $\Delta \ks\approx2$ mag, while in Trumpler 14 it is $\Delta \ks\approx5$ mag, consistent with the estimated ages., Comment: 25 pages, 11 figures. Accepted by New Astronomy

The determination of structural parameters of 11 faint Galactic globular clusters that, in most cases, had not been previously studied in this context. The clusters are IC1257, Lynga7, Terzan4, Terzan10, BH176, ESO452-SC11, ESO280-SC08, 2MASS-GC01, 2MASS-GC02, GLIMPSE-C01 and AL3, which are projected not far from the central region of the Galaxy. Field-star contamination is significant in the colour-magnitude diagrams. Stellar radial number-density and surface-brightness profiles are built with 2MASS photometry that, for the present clusters, corresponds basically to giant-branch stars. Field-star decontamination is essential for clusters in dense fields. With decontaminated photometry we also compute the total MV of four such globular clusters, using M4 as a template. King-like functions are fitted to the radial profiles, from which the core, half-light, half-star count and tidal radii are derived, together with the concentration parameter. Parameters derived here are compared to the equivalent ones of other Galactic globular clusters available in the literature. Structural parameters and luminosity of most of the faint globular clusters dealt with in this paper are consistent with those of Palomar-like (low-mass and loose structure) globular clusters. This work helps to improve coverage of the globular cluster parameter space., Comment: 11 pages, 9 figs. Accepted by A&A

We investigate the nature of the recently catalogued star cluster candidate FSR584, which is projected in the direction of the molecular cloud W3 and may be the nearest globular cluster to the Sun. 2MASS CMDs, the stellar radial density profile, and proper motions are employed to derive fundamental and structural parameters. The CMD morphology and the radial density profile show that FSR584 is an old star cluster. With proper motions, the properties of FSR584 are consistent with a metal-poor globular cluster with a well-defined turnoff and evidence of a blue horizontal-branch. FSR584 might be a Palomar-like halo globular cluster that is moving towards the Galactic plane. The distance from the Sun is approx 1.4kpc, and it is located at approx 1kpc outside the Solar circle. The radial density profile is characterized by a core radius of rc=0.3+/-0.1 pc. However, we cannot exclude the possibility of an old open cluster. Near-infrared photometry coupled to proper motions support the scenario where FSR584 is a new globular cluster in the Galaxy. The absorption is A_V=9.2+/-0.6$, which makes it a limiting object in the optical and explains why it has so far been overlooked, Comment: Astronomy and Astrophysics, accepted. 6 pages and 6 figures

We derive accurate parameters related to the CMD, structure and dynamical state of M52 and NGC3960, whose fields are affected by differential reddening. Compared to open clusters in different dynamical states studied with similar methods, the core and overall parameters of M52 are consistent with an open cluster more massive than 1000Mo and ~60Myr old, with some mass segregation in the inner region. The core of NGC3960 is in an advanced dynamical state with strong mass segregation in the core/halo region, while the somewhat flat overall MF (x~1.07) suggests low-mass star evaporation. The excess stellar density in the core may suggest post-core collapse. The dynamical evolution of NGC3960 may have been accelerated by the tidal Galactic field, since it lies \~0.5kpc inside the Solar circle., Comment: 15 pages and 8 figures. Astronomy and astrophysics, in press

We derive the structure, distribution of MS and PMS stars and dynamical state of the young open cluster NGC 4755. We explore the possibility that, at the cluster age, some MS and PMS stars still present infrared excesses related to dust envelopes and proto-planetary discs. The radial density profile follows King's law with a core radius $\rm\rc=0.7\pm0.1 pc$ and a limiting radius $\rm\rl=6.9\pm0.1 pc$; the cluster age is $\rm14\pm2 Myr$. Field-star decontamination reveals a low-MS limit at $\rm\approx1.4 \ms$. The core MF ($\chi=0.94\pm0.16$) is flatter than the halo's ($\chi=1.58\pm0.11$). NGC 4755 contains $\rm\sim285$ candidate PMS stars of age $\rm\sim1 - 15 Myr$, and a few evolved stars. The mass locked up in PMS, MS and evolved stars amounts to $\rm\sim1150 \ms$. Proper motions show that \ks-excess MS and PMS stars are cluster members. \ks-excess fractions in PMS and MS stars are $\rm5.4\pm2.1%$ and $\rm3.9\pm1.5%$ respectively, consistent with the cluster age. The core is deficient in PMS stars, as compared with MS ones. NGC 4755 hosts binaries in the halo but they are scarce in the core. Compared to open clusters in different dynamical states studied with similar methods, NGC 4755 fits relations involving structural and dynamical parameters in the expected locus for its age and mass. On the other hand, the flatter core MF probably originates from primordial processes related to parent molecular cloud fragmentation and mass segregation over $\rm\sim14 Myr$. Star formation in NGC 4755 began $\rm\approx14 Myr$ ago and proceeded for about the same length of time. Detection of \ks-excess emission in member MS stars suggests that some circumstellar dust discs survived for $\rm\sim10^7 yr$, occurring both in some MS and PMS stars for the age and spread observed in NGC 4755., Comment: 10 figs. Astronomy & Astrophysics, in press

We present BVI photometry of the globular cluster NGC 6642 using the SOI imager at the SOAR Telescope. The Colour Magnitude Diagrams (CMD) reach $\approx$1.5mag in V below the main sequence turn-off. A comparison of the overall sequences, and in particular the Red Giant Branch slope of NGC 6642 with that of M~5 indicates that the two clusters must have a similar metallicity of [Fe/H]$\approx$-1.3. We also obtain for NGC 6642 a reddening E(B-V)=0.42$\pm$0.03, and a distance from the Sun of d$_{\odot}$=7.2$\pm$0.5 kpc. Therefore NGC 6642 is a moderately metal-poor globular cluster, spatially located in the bulge, at a galactocentric distance of R$_{\rm GC}$$\approx$1.7 kpc. The comparison of CMDs of NGC 6642 with those of M~5 shows that there is a very good match of magnitude difference between turn-off and horizontal branch, suggesting comparable ages. M~5 has an age typical of the halo globulars, and consequently NGC 6642 is coeval with the halo. NGC 6642 is a good candidate to be one of the few genuine metal-poor and old {\it bulge} clusters, and might be one of the most ancient fossils in the Galaxy., Comment: barbuy.tar.gz: 13 pages, 7 figures, includes files aa.cls, psfig.tex

We use 2MASS photometry to study colour-magnitude and colour-colour diagrams, structure and mass distribution in the ionizing open cluster NGC\,6611. Reddening variation throughout the cluster region is taken into account followed by field-star decontamination of the CMDs. The field-star decontamination showed that the lower limit of the main sequence (MS) occurs at $\rm\approx5\,\ms$. Based on the fraction of Ks excess stars in the colour-colour diagram we estimate an age of $1.3\pm0.3$\,Myr which is consistent with the presence of a large number of pre-main sequence (PMS) stars. The radial density distribution including MS and PMS stars is fitted by a King profile with a core radius $0.70\pm0.08\,pc$. The cluster density profile merges into the background at a limiting radius $6.5\pm0.5\,pc$. In the halo and through the whole cluster the MFs have slopes $\rm\chi=1.52\pm0.13$ and $\rm\chi=1.45\pm0.12$, respectively, thus slightly steeper than Salpeter's IMF. In the core the MF is flat, $\rm\chi=0.62\pm0.16$, indicating some degree of mass segregation since the cluster age is a factor $\sim2$ larger than the relaxation time. Because of the very young age of NGC\,6611, part of this effect appears to be related to the molecular cloud-fragmentation process itself. We detect $362\pm120$ PMS stars. The total observed mass including detected MS (in the range $\rm5-85\,\ms$) and PMS stars amounts to $\sim1\,600\,\ms$, thus more massive than the Trapezium cluster. Compared to older open clusters of different masses, the overall NGC\,6611 fits in the relations involving structural and dynamical parameters. However, the core is atypical in the sense that it looks like an old/dynamically evolved core. Again, part of this effect must be linked to formation processes.

We use the open clusters (OCs) with known parameters available in the WEBDA database and in recently published papers to derive properties related to the disk structure. The sample totals 654 OCs, consisting basically of Trumpler types I to III clusters. Because of the completeness effects, the observed radial distribution of OCs with respect to Galactocentric distance does not follow the expected exponential profile. We simulate the effects of completeness assuming that the observed distribution of the number of OCs with a given number of stars above the background, measured in a restricted zone outside the Solar circle, is representative of the intrinsic distribution of OCs throughout the Galaxy. As a result we derive completeness-corrected radial distributions which agree with exponential disks throughout the observed Galactocentric distance range 5--14\,kpc, with scale lengths in the range $1.5 - 1.9\,kpc$. In particular we retrieve the expected exponential-disk radial profile for the highly depleted regions internal to the Solar circle. Extrapolation of the completeness-corrected radial distributions down to the Galactic center indicates a total number of OCs in the range $\rm(1.8 - 3.7)\times10^5$. These estimates are upper-limits because they do not take into account depletion in the number of OCs by dynamical effects in the inner parts of the Galaxy. The observed and completeness-corrected age-distributions of the OCs can be fitted by a combination of two exponential-decay profiles characterized by age scales of $\rm\sim100\,Myr$ and $\rm\sim1.9\,Gyr$, respectively. This rules out evolutionary scenarios based on constant star-formation and OC-disruption rates. We estimate that 3.4--8\% of the embedded clusters do actually emerge from the parent molecular clouds as OCs., Comment: 17 pages and 17 figures