- ID:
- ivo://CDS.VizieR/J/A+A/616/A10
- Title:
- 46 open clusters GaiaDR2 HR diagrams
- Short Name:
- J/A+A/616/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky. The precision, accuracy, and homogeneity of both astrometry and photometry are unprecedented. We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD). Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Instead, we have chosen several illustrative examples. We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Many fine structures of the HRDs are presented. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. The relation between kinematics and the HRD is nicely illustrated. Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. Membership and mean parameters for a selected list of open clusters are provided. They allow drawing very detailed cluster sequences, highlighting fine structures, and providing extremely precise empirical isochrones that will lead to more insight in stellar physics. Gaia DR2 demonstrates the potential of combining precise astrometry and photometry for large samples for studies in stellar evolution and stellar population and opens an entire new area for HRD-based studies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/470/3937
- Title:
- 1876 open clusters multimembership catalog
- Short Name:
- J/MNRAS/470/3937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The main objective of this work is to determine the cluster members of 1876 open clusters, using positions and proper motions of the astrometric fourth United States Naval Observatory (USNO) CCD Astrograph Catalog (UCAC4). For this purpose, we apply three different methods, all based on a Bayesian approach, but with different formulations: a purely parametric method, another completely non-parametric algorithm and a third, recently developed by Sampedro & Alfaro (2016MNRAS.457.3949S), using both formulations at different steps of the whole process. The first and second statistical moments of the members' phase-space subspace, obtained after applying the three methods, are compared for every cluster. Although, on average, the three methods yield similar results, there are also specific differences between them, as well as for some particular clusters. The comparison with other published catalogues shows good agreement. We have also estimated, for the first time, the mean proper motion for a sample of 18 clusters. The results are organized in a single catalogue formed by two main files, one with the most relevant information for each cluster, partially including that in UCAC4, and the other showing the individual membership probabilities for each star in the cluster area. The final catalogue, with an interface design that enables an easy interaction with the user, is available in electronic format at the Stellar Systems Group (SSG-IAA) web site (http://ssg.iaa.es/en/content/sampedro-cluster-catalog).
- ID:
- ivo://CDS.VizieR/J/AJ/105/1822
- Title:
- Open clusters near eta Car
- Short Name:
- J/AJ/105/1822
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Proper motions and photographic photometry have been derived for nearly 600 stars with 7.5 < V < 15.5 in the region of the very young open clusters Tr 14, Tr 16, and Cr 232 based on 26 plates dating from 1893 to 1990. Cluster membership probabilities have been derived from the proper motions and color-magnitude diagrams of probable members of each cluster are presented. In contrast to a few of the previous studies we find all three clusters to lie at the same distance.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A102
- Title:
- 3794 open clusters parameters
- Short Name:
- J/A+A/652/A102
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The structure and evolution of the spiral arms of the Milky Way are basic but long-standing questions in astronomy. Especially the lifetime of spiral arms, it is still a puzzle and has not been well constrained from observations. In this work, we aim to inspect these issues by using a large catalogue of open clusters. We have compiled a catalogue of 3794 OCs based on Gaia EDR3. A majority of them have accurately determined parallaxes, proper motions and radial velocities. The age parameters for these OCs are also collected or calculated. Then, we analysed their distributions on the Galactic plane, the kinematic properties, the vertical distributions and the regressed properties of subsamples of OCs in order to better understand the nearby spiral structure and its evolution. We find evidence that the nearby spiral arms are compatible with a long lived pattern and might have remained approximately stable for the past 80 million years. Especially, the Local Arm where our Sun is currently located in, is also suggested to be long-lived in nature, and probable a major arm segment in the Milky Way. The evolutionary characteristics of nearby spiral arms show that the dynamic spiral mechanism might be not suitable for our Galaxy. Instead, the density wave theory is more consistent with the observational properties.
- ID:
- ivo://CDS.VizieR/J/A+A/446/949
- Title:
- Open clusters proper motions based on UCAC2
- Short Name:
- J/A+A/446/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the kinematics of hundreds of open clusters, based on the UCAC2 Catalogue positions and proper motions. Membership probabilities were obtained for the stars in the cluster fields by applying a statistical method uses stellar proper motions. All open clusters with known distance were investigated, and for 75 clusters this is the first determination of the mean proper motion. The results, including the DSS images of the cluster's fields with the kinematic members marked, are incorporated in the Open Clusters Catalogue supported on line by our group.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A116
- Title:
- Open clusters within 1.8 kpc of the Sun
- Short Name:
- J/A+A/593/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on an almost complete sample of Galactic open star clusters within 1.8kpc, we perform a comprehensive statistical analysis of various cluster parameters like spatial position, age, size, mass and extinction in order to understand the general properties of the open cluster system in the Galaxy and the Galactic structure. Based on the distribution of 1241 open clusters about the Galactic plane and in different age bins, we find the average Galactic scale height as Zh=60+/-2pc for the youngest cluster population having Age<700Myr, however, it increases up to 64+/-2pc when we also include older population of clusters. The solar offset is found to be 6.2+/-1.1pc above the formal Galactic plane. We derive a local mass density of {rho}_0_=0.090+/-0.005M_{sun}_/pc^3^ and found a negligibly small amount of dark matter in the solar neighbourhood. The reddening in the direction of clusters suggests a strong correlation with their vertical distance from the Galactic plane having a respective slope of dE(B-V)/dz=0.40+/-0.04 and 0.42+/-0.05 mag/kpc below and above the GP. We observe a linear mass-radius and mass-age relations in the open clusters and derive a slope of dR/d(logM)=2.08+/-0.10 and d(logM)/d(logT)=-0.36+/-0.05,respectively.
437. Open cluster TR 10
- ID:
- ivo://CDS.VizieR/I/216A
- Title:
- Open cluster TR 10
- Short Name:
- I/216A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Positions for 979 stars in the area of Tr 10 are derived from fifteen plates taken recently with the ICDA refractor. For the determination of proper motions nine plates of the Cape Astrographic Catalogue are used as first epoch. The results make it appear doubtful that the object is a single cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/369/511
- Title:
- Open star clusters. III. NGC 4103, 5281, 4755
- Short Name:
- J/A+A/369/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables 5, 7, and 8 contain the data of the CCD photometry of the three open star clusters. We added the numbering systems of previously published papers to the tables. Table 5 contains the data of NGC 4103 with stellar numbers from Wesselink (1969MNRAS.146..329W); Table 7 the data of NGC 5281 with the numbers of Moffat & Vogt (1973A&AS...10..135M); Table 8 the data of NGC 4755 with the numbering system according to Arp & van Sant (1958AJ.....63..341A). In Tables 12, 13, and 14 we present relative proper motions of the three clusters (in the same sequence). For NGC 4103 the table contains the information of an entire Carte du Ciel field of 2 degrees square, for the other two clusters, a small subfield had to be selected beforehand. The numbers of Arp & van Sant (1958AJ.....63..341A) are encrypted in the following way: Numbers <100 stand for the stars A to Q, the first digit of the numbers >100 represents the quadrant. The two final digits are the running numbers in the notation of Arp & van Sant (1958AJ.....63..341A).
- ID:
- ivo://CDS.VizieR/J/A+A/349/448
- Title:
- Open star clusters. I. NGC 581 (M 103)
- Short Name:
- J/A+A/349/448
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry and a proper motion study of the young open star cluster, NGC 581 (M 103). Fitting isochrones to the colour magnitude diagram, we found an age of 16+/-4Myr and a distance of roughly 3kpc for this cluster. The proper motion study identifies 77 stars of V=14.5mag or brighter to be cluster members. We combine membership determination by proper motions and statistical field star subtraction to derive the IMF of the cluster and find a quite steep slope of {Gamma}=-1.80.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/59
- Title:
- Ophiuchus stellar stream with PS1 data
- Short Name:
- J/ApJ/809/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ophiuchus stream is a recently discovered stellar tidal stream in the Milky Way. We present high-quality spectroscopic data for 14 stream member stars obtained using the Keck and MMT telescopes. We confirm the stream as a fast moving (v_los_~290km/s), kinematically cold group ({sigma}_{nu}_los__<~1km/s) of {alpha}-enhanced and metal-poor stars ([{alpha}/Fe]~0.4dex, [Fe/H]~-2.0dex). Using a probabilistic technique, we model the stream simultaneously in line-of-sight velocity, color-magnitude, coordinate, and proper motion space, and so determine its distribution in 6D phase-space. We find that the stream extends in distance from 7.5 to 9kpc from the Sun; it is 50 times longer than wide, merely appearing highly foreshortened in projection. The analysis of the stellar population contained in the stream suggests that it is ~12Gyr old, and that its initial stellar mass was ~2x10^4^M_{sun}_ (or at least >~7x10^3^M_{sun}_). Assuming a fiducial Milky Way potential, we fit an orbit to the stream that matches the observed phase-space distribution, except for some tension in the proper motions: the stream has an orbital period of ~350Myr, and is on a fairly eccentric orbit (e~0.66) with a pericenter of ~3.5kpc and an apocenter of ~17kpc. The phase-space structure and stellar population of the stream show that its progenitor must have been a globular cluster that was disrupted only ~240Myr ago. We do not detect any significant overdensity of stars along the stream that would indicate the presence of a progenitor, and conclude that the stream is all that is left of the progenitor.
