- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AcA/52/143
- Title:
- OGLE high proper motion stars towards MC
- Short Name:
- J/AcA/52/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of high proper motion (HPM) stars detected in the foreground of central parts of the Magellanic Clouds. The Catalog contains 2161 objects in the 4.5 square degree area towards the LMC, and 892 HPM stars in the 2.4 square degree area towards the SMC. The Catalog is based on observations collected during four years of the OGLE-II microlensing survey. The Difference Image Analysis (DIA) of the images provided candidate HPM stars with proper motion as small as 4mas/yr. These appeared as pseudo-variables, and were all measured astrometrically on all CCD images, providing typically about 400 data points per star. The reference frame was defined by the majority of background stars, most of them members of the Magellanic Clouds. The reflex motion due to solar velocity with respect to the local standards of rest is clearly seen. The largest proper motion in our sample is 363mas/yr. Parallaxes were measured with errors smaller than 20% for several stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/348/1439
- Title:
- OGLE II Galactic center proper motions
- Short Name:
- J/MNRAS/348/1439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a proper-motion catalogue of 5080236 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge (GB) fields, covering a range of -11{deg}<l<11{deg} and -6{deg}<b<3{deg}, the total area close to 11deg^2^. The proper-motion measurements are based on 138-555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11<I<18mag. In particular, the catalogue includes red clump giants and red giants in the GB, and main-sequence stars in the Galactic disc. The proper motions up to pm=500mas/yr were measured with a mean accuracy of 0.8-3.5mas/yr, depending on the brightness of a star. This catalogue may be useful for studying the kinematics of stars in the GB and the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/385/905
- Title:
- OGLEII high pm stars towards Galactic Centre
- Short Name:
- J/MNRAS/385/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The photometry data base of the second phase of the OGLE microlensing experiment, OGLE-II, is a rich source of information about the kinematics and structure of the Galaxy. In this work, we use the OGLE-II proper motion catalogue to identify candidate stars which have high proper motions. 521 stars with proper motion {mu}>50mas/yr in the OGLE-II proper motion catalogue were cross-identified with stars in the MACHO high proper motion catalogue, and the DEep Near-Infrared Survey and Two-Micron All-Sky Survey infrared photometry catalogues. Photometric distances were computed for stars with colours consistent with G/K- and M-type stars. Six stars were newly identified as possible nearby (<50pc) M dwarfs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/327/601
- Title:
- OGLE-II High proper motion stars
- Short Name:
- J/MNRAS/327/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The difference image analysis (DIA) of the images obtained by the Optical Gravitational Lensing Experiment (OGLE-II) revealed a peculiar artefact in the sample of stars proposed as variable by Woniak in one of the Galactic bulge fields: the occurrence of pairs of candidate variables showing anti-correlated light curves monotonic over a period of 3 yr. This effect can be understood, quantified and related to the stellar proper motions. DIA photometry supplemented with a simple model offers an effective and easy way to detect high proper motion stars in very dense stellar fields, where conventional astrometric searches are extremely inefficient.
- ID:
- ivo://CDS.VizieR/II/322
- Title:
- OGLE-III. Magellanic Clouds stellar proper motions
- Short Name:
- II/322
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of over 6.2million stars with measured proper motions. All these stars are observed in the direction of the Magellanic Clouds within the brightness range 12<I<19mag. Based on these proper motions about 440000 Galactic foreground stars can be selected. Because the proper motions are based on a few hundred epochs collected during eight years, their statistical uncertainties are below 0.5mas/yr for stars brighter than I=18.5mag. The parallaxes are derived with uncertainties down to 1.6mas. For above 13000 objects parallaxes are derived with significance above 3{sigma}, which allows selecting about 270 white dwarfs (WDs). The search for common proper motion binaries among stars presented was performed resulting in over 500 candidate systems. The most interesting ones are candidate halo main sequence star-WD and WD-WD systems. The application of the catalog to the empirically bound Cepheid instability strip is also discussed.
- ID:
- ivo://CDS.VizieR/J/AcA/61/199
- Title:
- OGLE3 Magellanic Clouds High proper motion stars
- Short Name:
- J/AcA/61/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for High Proper Motion (HPM) stars, i.e., the ones with pm>100mas/yr, in the direction to the Magellanic Clouds. This sky area was not examined in detail as the high stellar density hampers efforts in performing high-quality astrometry.
- ID:
- ivo://CDS.VizieR/J/MNRAS/495/2882
- Title:
- Open cluster radii from Gaia proper motions
- Short Name:
- J/MNRAS/495/2882
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we improve a previously published method to calculate in a reliable way the radius of an open cluster (OC). The method is based on the behaviour of stars in the proper motion space as the sampling changes in the position space. Here, we describe the new version of the method and show its performance and robustness. Additionally, we apply it to a large number of OCs using data from Gaia second data release to generate a catalogue of 401 clusters with reliable radius estimations. The range of obtained apparent radii goes from Rc=1.4+/-0.1arcmin (for the cluster FSR 1651) to Rc=25.5+/-3.5arcmin (for NGC 2437). Cluster linear sizes follow very closely a lognormal distribution with a mean characteristic radius of Rc=3.7pc, and its high radius tail can be fitted by a power law as N{prop.to}Rc^-3.11+/-0.35^. Additionally, we find that number of members, cluster radius, and age follow the relationship Nc{prop.to}Rc^1.2+/-0.1^.Tc^-1.9+/-0.4^ where the younger and more extensive the cluster, the more members it presents. The proposed method is not sensitive to low density or irregular spatial distributions of stars and, therefore, is a good alternative or complementary procedure to calculate OC radii not having previous information on star memberships.
- ID:
- ivo://CDS.VizieR/J/A+AS/146/251
- Title:
- Open clusters absolute proper motions. I.
- Short Name:
- J/A+AS/146/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mean proper motions and parallaxes of 205 open clusters were determined from their member stars found in the Hipparcos (<I/239>) Catalogue. 360 clusters were searched for possible members, excluding nearby clusters with distances D<200pc. Members were selected using ground based information (photometry, radial velocity, proper motion, distance from the cluster centre) and information provided by Hipparcos (proper motion, parallax). Altogether 630 certain and 100 possible members were found. A comparison of the Hipparcos parallaxes with photometric distances of open clusters shows good agreement. The Hipparcos data confirm or reject the membership of several Cepheids in the studied clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/136/118
- Title:
- Open clusters as galactic disk tracers. I.
- Short Name:
- J/AJ/136/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have begun a survey of the chemical and dynamical properties of the Milky Way disk as traced by open star clusters. In this first contribution, the general goals of our survey are outlined and the strengths and limitations of using star clusters as a Galactic disk tracer sample are discussed. We also present medium-resolution (R~150000) spectroscopy of open cluster stars obtained with the Hydra multi-object spectrographs on the Cerro Tololo Inter-American Observatory 4m and WIYN 3.5m telescopes. Here we use these data to determine the radial velocities of 3436 stars in the fields of open clusters within about 3kpc, with specific attention to stars having proper motions in the Tycho-2 catalog. Additional radial velocity members (without Tycho-2 proper motions) that can be used for future studies of these clusters were also identified.
