- ID:
- ivo://CDS.VizieR/J/A+A/486/453
- Title:
- NIR photometry of early-type stars in Cyg OB2
- Short Name:
- J/A+A/486/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cygnus OB2 is one of the richest OB associations in the local Galaxy, and is located in a vast complex containing several other associations, clusters, molecular clouds, and HII regions. However, the stellar content of Cygnus OB2 and its surroundings remains rather poorly known largely due to the considerable reddening in its direction at visible wavelength. We investigate the possible existence of an extended halo of early-type stars around Cygnus OB2, which is hinted at by near-infrared color-color diagrams, and its relationship to Cygnus OB2 itself, as well as to the nearby association Cygnus OB9 and to the star forming regions in the Cygnus X North complex. Candidate selection is made with photometry in the 2MASS all-sky point source catalog. The early-type nature of the selected candidates is confirmed or discarded through our infrared spectroscopy at low resolution. In addition, spectral classifications in the visible are presented for many lightly-reddened stars.
Number of results to display per page
Search Results
652. NIR sources in S106
- ID:
- ivo://CDS.VizieR/J/AJ/131/1608
- Title:
- NIR sources in S106
- Short Name:
- J/AJ/131/1608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of deep near-infrared observations searching for very low mass young stellar objects (YSOs) in the massive star-forming region of S106 taken with the Subaru Telescope. The survey, whose limiting magnitude exceeds 20mag in the JHK' bands, is sensitive enough to provide unprecedented details in the two nebular lobes. In addition, it reveals a census of the stellar population down to objects below the deuterium-burning limit, a fiducial boundary between brown dwarfs and planetary-mass objects. Based on color-color diagrams, nearly 600 embedded YSO candidates with near-infrared excesses have been identified in an area of ~5'x5' that are not uniformly distributed but centrally concentrated.
- ID:
- ivo://CDS.VizieR/J/AJ/154/29
- Title:
- Observation of 148 young stars toward NGC 1980
- Short Name:
- J/AJ/154/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC1980 is a young cluster that is located about 0.5{deg} south of the Orion Nebula Cluster (ONC). Recent studies by Bouy et al. and Pillitteri et al. have suggested that NGC1980 contains an older population of stars compared to a much younger ONC, and that it belongs to a foreground population that may be located in front of the Orion A molecular gas by as much as 40pc. In this work, we present low-resolution spectra toward 148 young stars found toward the NGC1980 region. We determine the spectral types of these stars, examine accretion signatures and measure the extinction toward them. We determine that based on these observations, the age of the population of NGC1980 is indistinguishable from L1641, estimated to be ~3Myr, comparable with the study by Fang et al.
- ID:
- ivo://CDS.VizieR/J/AJ/159/199
- Title:
- OCCAM. IV. Open cluster abundances using APOGEE DR16
- Short Name:
- J/AJ/159/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Open Cluster Chemical Abundances and Mapping (OCCAM) survey aims to constrain key Galactic dynamical and chemical evolution parameters by the construction of a large, comprehensive, uniform, infrared-based spectroscopic data set of hundreds of open clusters. This fourth contribution from the OCCAM survey presents analysis using Sloan Digital Sky Survey/APOGEE DR16 of a sample of 128 open clusters, 71 of which we designate to be "high quality" based on the appearance of their color-magnitude diagram. We find the APOGEE DR16 derived [Fe/H] abundances to be in good agreement with previous high-resolution spectroscopic open cluster abundance studies. Using the high-quality sample, we measure Galactic abundance gradients in 16 elements, and find evolution of some of the [X/Fe] gradients as a function of age. We find an overall Galactic [Fe/H] versus Rgc gradient of -0.068{+-}0.001dex/kpc over the range of 6<Rgc<13.9kpc; however, we note that this result is sensitive to the distance catalog used, varying as much as 15%. We formally derive the location of a break in the [Fe/H] abundance gradient as a free parameter in the gradient fit for the first time. We also measure significant Galactic gradients in O, Mg, S, Ca, Mn, Cr, Cu, Na, Al, and K, some of which are measured for the first time. Our large sample allows us to examine four well-populated age bins in order to explore the time evolution of gradients for a large number of elements and comment on possible implications for Galactic chemical evolution and radial migration.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A14
- Title:
- OCCASO IV. open cluster stars radial velocities
- Short Name:
- J/A+A/658/A14
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Open clusters (OCs) are widely used as test particles to investigate a variety of astrophysical phenomena, from stellar evolution to Galactic evolution. Gaia and the complementary massive spectroscopic surveys are providing an unprecedented wealth of information about these systems. The Open Cluster Chemical Abundances from Spanish Observatories (OCCASO) survey aims to complement all this work by determining OCs' accurate radial velocities and chemical abundances from high-resolution, R>=60000, spectra. Methods. Radial velocities were obtained by cross-correlating the observed spectra with a library of synthetic spectra that covers early M to A spectral types. We provide radial velocities for 336 stars including several Gaia benchmark stars and objects belonging to 51 open clusters. The internal uncertainties of the derived radial velocities go from 10m/s to 21m/s as a function of the instrumental configuration used. The derived radial velocities, together with the Gaia proper motions, were used to investigate the cluster membership of the observed stars. After this careful membership analysis, we obtained average velocities for 47 open clusters. To our knowledge, this is the first radial velocity determination for five of these clusters. Finally, the radial velocities, proper motions, distances and ages were used to investigate the kinematics of the observed clusters and in the integration of their orbits.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/3150
- Title:
- OCCASO survey. HRV for 12 open clusters
- Short Name:
- J/MNRAS/458/3150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters (OCs) are crucial for studying the formation and evolution of the Galactic disc. However, the lack of a large number of OCs analyzed homogeneously hampers the investigations about chemical patterns and the existence of Galactocentric radial and vertical gradients, or an age-metallicity relation. To overcome this, we have designed the Open Cluster Chemical Abundances from Spanish Observatories survey (OCCASO). We aim to provide homogeneous radial velocities, physical parameters and individual chemical abundances of six or more Red Clump stars for a sample of 25 old and intermediate-age OCs visible from the Northern hemisphere. To do so, we use high resolution spectroscopic facilities (R~62,000) available at Spanish observatories. We present the motivation, design and current status of the survey, together with the first data release of radial velocities for 77 stars in 12 OCs, which represents about 50% of the survey. We include clusters never studied with high-resolution spectroscopy before (NGC 1907, NGC 6991, NGC 7762), and clusters in common with other large spectroscopic surveys like the Gaia-ESO Survey (NGC 6705) and APOGEE (NGC 2682 and NGC 6819). We perform internal comparisons between instruments to evaluate and correct internal systematics of the results, and compare our radial velocities with previous determinations in the literature, when available. Finally, radial velocities for each cluster are used to perform a preliminar kinematic study in relation with the Galactic disc.
657. OGLE SMC clusters
- ID:
- ivo://CDS.VizieR/J/AcA/48/175
- Title:
- OGLE SMC clusters
- Short Name:
- J/AcA/48/175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of clusters found in the area of ~2.4 square degrees in the central region of the Small Magellanic Cloud. The catalog contains data for 238 clusters, 72 of them are new objects. For each cluster equatorial coordinates, radii, approximate number of members, cross-identification, finding chart and color magnitude diagrams: V-(B-V) and V-(V-I) are provided.
- ID:
- ivo://CDS.VizieR/J/AcA/56/219
- Title:
- OGLE variable stars in NGC 6259
- Short Name:
- J/AcA/56/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for variable stars in the field of NGC6259. Altogether 85 variable stars have been discovered. 36 of them are eclipsing systems. This group contains 13 EA, 2 EB and 21 EW-type stars. Light curves of two variable stars resemble those of Miras. The remaining 47 variable stars detected in the field of this open cluster are most probably highly obscured red giants (OSARG, irregular). For all detected variable stars we provide their light curves, preliminary classification, discussion on the possible cluster membership, equatorial coordinates, finding charts and periods when possible.
- ID:
- ivo://CDS.VizieR/J/MNRAS/409/1281
- Title:
- Old star clusters in the FSR catalogue
- Short Name:
- J/MNRAS/409/1281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the old star clusters in the sample of cluster candidates from the Froebrich, Scholz & Raftery (FSR, 2007, Cat. J/MNRAS/374/399) list. Based on photometry from the Two-Micron All-Sky Survey, we generated decontaminated colour-magnitude and colour-colour diagrams to select a sample of 269 old stellar clusters. This sample contains 63 known globular clusters, 174 known open clusters and 32 so far unclassified objects. Isochrone fitting has been used to homogeneously calculate the age, distance and reddening to all clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A134
- Title:
- Omega Cen lower red giant stars abundances
- Short Name:
- J/A+A/618/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Li, Na, Al and Fe abundances of 199 lower red giant branch stars members of the stellar system Omega Centauri, using high-resolution spectra acquired with FLAMES at the Very Large Telescope. The A(Li) distribution is peaked at A(Li)~1dex with a prominent tail toward lower values. The peak of the distribution well agrees with the lithium abundances measured in lower red giant branch stars in globular clusters and Galactic field stars. Stars with A(Li)~1dex are found at metallicities lower than [Fe/H]~-1.3dex but they disappear at higher metallicities. On the other hand, Li-poor stars are found at all the metallicities. The most metal-poor stars exhibit a clear Li-Na anticorrelation, with about 30% of the sample with A(Li) lower than ~0.8dex, while in normal globular clusters these stars represent a small fraction. Most of the stars with [Fe/H]>-1.6dex are Li-poor and Na-rich. The Li depletion measured in these stars is not observed in globular clusters with similar metallicities and we demonstrate that it is not caused by the proposed helium enhancements and/or young ages. Hence, these stars formed from a gas already depleted in lithium. Finally, we note that Omega Centauri includes all the populations (Li-normal/Na-normal, Li-normal/Na-rich and Li-poor/Na-rich stars) observed, to a lesser extent, in mono-metallic GCs.
