- ID:
- ivo://CDS.VizieR/J/A+A/561/A142
- Title:
- Galactic extinction from SDSS BHB stars
- Short Name:
- J/A+A/561/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use 12530 photometrically-selected BHB stars from Sloan Digital Sky Survey DR7 to estimate, the total extinction of the Milky Way in high Galactic latitude, RV and AV in each line of sight. A Bayesian method is developed to estimate the reddening values in the given lines of sight. Based on the most likely values of reddening in multiple colors, we are able to derive the values of RV and AV. We select 94 zero-reddened BHB stars from 7 globular cluster as the template. The reddening in the 4 SDSS colors for the northern Galactic cap are estimated by comparing the field BHB stars with the template stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/5138
- Title:
- Galactic GC mean proper motions & velocities
- Short Name:
- J/MNRAS/482/5138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived the mean proper motions and space velocities of 154 Galactic globular clusters and the velocity dispersion profiles of 141 globular clusters based on a combination of Gaia DR2 proper motions with ground-based line-of-sight velocities. Combining the velocity dispersion profiles derived here with new measurements of the internal mass functions allows us to model the internal kinematics of 144 clusters, more than 90 per cent of the currently known Galactic globular cluster population. We also derive the initial cluster masses by calculating the cluster orbits backwards in time applying suitable recipes to account for mass-loss and dynamical friction. We find a correlation between the stellar mass function of a globular cluster and the amount of mass lost from the cluster, pointing to dynamical evolution as one of the mechanisms shaping the mass function of stars in clusters. The mass functions also show strong evidence that globular clusters started with a bottom-light initial mass function. Our simulations show that the currently surviving globular cluster population has lost about 80 per cent of its mass since the time of formation. If globular clusters started from a lognormal mass function, we estimate that the Milky Way contained about 500 globular clusters initially, with a combined mass of about 2.5x10^8^M_{sun}_. For a power-law initial mass function, the initial mass in globular clusters could have been a factor of three higher.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/89
- Title:
- 5 Galactic GC proper motions from Gaia DR1
- Short Name:
- J/ApJ/839/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho-Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneous PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope (HST) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST. By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.
- ID:
- ivo://CDS.VizieR/J/A+A/474/121
- Title:
- Galactic globular cluster 2MASS GC02 JKs phot.
- Short Name:
- J/A+A/474/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep infrared images and K-band spectra of the Galactic globular cluster 2MASS GC02. A variable star search has also been carried out. Some basic physical properties of the cluster, such as metallicity, reddening, distance modulus and radial velocity, are derived. These measurements are based on an analysis of the J-Ks versus Ks color-magnitude diagram of the cluster. Spectroscopically derived metallicities and radial velocities of 15 stars are presented. In addition, periods and amplitudes are provided for five RR Lyrae stars discovered in the field. The cluster is moderately metal-rich and has a relatively high radial velocity. Its horizontal branch appears to be predominantly red, though our photometry cannot rule out the presence of a blue component as seen in NGC 6388 and NGC 6441. Similar to these two clusters, the detected RR Lyrae stars in GC02 have anomalously long periods for the cluster's moderately high metallicity, which suggests that it too is an Oosterhoff type III cluster. Comparison with the existing kinematic and abundance information for the Galactic globular clusters shows that GC02 most probably belongs to the bulge sub population, although an inner halo association cannot be ruled out.
- ID:
- ivo://CDS.VizieR/VII/103
- Title:
- Galactic Globular Clusters
- Short Name:
- VII/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue collects, for the first time, the most important data concerning all the galactic globular clusters still well known. Here the objects enclosed in famous publications like the ones of Arp (1965), Alter et al. (1970), Alcaino (1973) are reported, with the addition of new clusters noticed recently (TER, ESO, UKS, TJ) and till KOD 1, found by K. Kodaira in July 1983 (IAUC 3846). The most important disposable data in literature have been found about every object. For the clusters found recently, the data may be fragmentary and susceptible of variations. A particular care has been utilized in the research of the most reliable informations and data, that have been homogenized and put in order later on.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/358
- Title:
- 4 Galactic globular clusters Fe line depths
- Short Name:
- J/MNRAS/434/358
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectrum syntheses for three elements (Mg, Na and Eu) in high-resolution integrated light spectra of the Galactic globular clusters 47 Tuc, M3, M13, NGC 7006 and M15 are presented, along with calibration syntheses of the solar and Arcturus spectra. Iron abundances in the target clusters are also derived from integrated light equivalent width analyses. Line profiles in the spectra of these five globular clusters are well fitted after careful consideration of the atomic and molecular spectral features, providing levels of precision that are better than equivalent width analyses of the same integrated light spectra, and that are comparable to the precision in individual stellar analyses. The integrated light abundances from the 5528 and 5711{AA} MgI lines, the 6154 and 6160{AA} NaI lines, and the 6645{AA} EuII line fall within the observed ranges from individual stars; however, these integrated light abundances do not always agree with the average literature abundances. Tests with the second parameter clusters M3, M13 and NGC 7006 show that assuming an incorrect horizontal branch morphology is likely to have only a small (<~0.06dex) effect on these Mg, Na and Eu abundances. These tests therefore show that integrated light spectrum syntheses can be applied to unresolved globular clusters over a wide range of metallicities and horizontal branch morphologies. Such high precision in integrated light spectrum syntheses is valuable for interpreting the chemical abundances of globular cluster systems around other galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/1725
- Title:
- Galactic globular clusters SDSS photometry
- Short Name:
- J/MNRAS/437/1725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present g' and z' aperture photometry for 96 Galactic globular clusters, making this the largest homogeneous catalogue of photometry for these objects in the Sloan Digital Sky Survey (SDSS) filter system. For a subset of 56 clusters, we also provide photometry in r' and i'. We carry out comparisons with previous photometry as well as with the SDSS data set. The data will be useful for a series of applications in Galactic and extragalactic astrophysics. Future papers will analyse the colour-metallicity relation, colour-magnitude diagrams and structural parameters. The compilation of results based on this data set will be collected in the Galactic Globular Cluster Catalog (G2C2).
- ID:
- ivo://CDS.VizieR/J/ApJ/700/523
- Title:
- Galactic star clusters in SDSS. II. Colors.
- Short Name:
- J/ApJ/700/523
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform an extensive test of theoretical stellar models for main-sequence (MS) stars in ugriz, using cluster fiducial sequences obtained in the previous paper of this series. We generate a set of isochrones using the Yale Rotating Evolutionary Code with updated input physics, and derive magnitudes and colors in ugriz from MARCS model atmospheres. These models match cluster MSs over a wide range of metallicity within the errors of the adopted cluster parameters. However, we find a large discrepancy of model colors at the lower MS (T_eff_<~4500K) for clusters at and above solar metallicity. We also reach similar conclusions using the theoretical isochrones of Girardi et al. and Dotter et al., but our new models are generally in better agreement with the data. Using our theoretical isochrones, we also derive MS-fitting distances and turnoff ages for five key globular clusters, and demonstrate the ability to derive these quantities from photometric data in the Sloan Digital Sky Survey. In particular, we exploit multiple color indices (g-r, g-i, and g-z) in the parameter estimation, which allows us to evaluate internal systematic errors. Our distance estimates, with an error of {sigma}_(m-M)_=0.03-0.11mag for individual clusters, are consistent with Hipparcos-based subdwarf-fitting distances derived in the Johnson-Cousins or Stromgren photometric systems.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/37
- Title:
- GALEX catalog of star clusters in M31
- Short Name:
- J/ApJS/199/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive catalog of 700 confirmed star clusters in the field of M31 compiled from three major existing catalogs. We detect 418 and 257 star clusters in Galaxy Evolution Explorer near-ultraviolet and far-ultraviolet (FUV) imaging, respectively. Our final catalog includes photometry of star clusters in up to 16 passbands ranging from FUV to NIR as well as ancillary information such as reddening, metallicity, and radial velocities. In particular, this is the most extensive and updated catalog of UV-integrated photometry for M31 star clusters. Ages and masses of star clusters are derived by fitting the multi-band photometry with model spectral energy distribution (SED); UV photometry enables more accurate age estimation of young clusters. Our catalog includes 182 young clusters with ages less than 1Gyr. Our estimated ages and masses of young clusters are in good agreement with previously determined values in the literature. The mean age and mass of young clusters are about 300Myr and 10^4^M_{sun}_, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/643
- Title:
- GALEX UV photometry of M31 Globular Clusters
- Short Name:
- J/ApJS/173/643
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ultraviolet (UV) photometry of M31 globular clusters (GCs) found in 23 Galaxy Evolution Explorer (GALEX) images covering the entirety of M31. We detect 485 and 273 GCs (and GC candidates) in the near-ultraviolet (NUV) and far-ultraviolet (FUV), respectively. The UV properties of GCs have been analyzed using various combinations of UV-optical and optical-optical colors. Comparing M31 data with those of Galactic GCs in the UV with the aid of population models, we find that the age ranges of old GCs in M31 and the Galactic halo are similar. Three metal-rich ([Fe/H]>-1) GCs in M31 produce significant FUV flux making their FUV-V colors unusually blue for their metallicities. These are thought to be analogs of the two peculiar Galactic GCs, NGC 6388 and NGC 6441, with extended blue HB stars. We detect 12 (10) intermediate-age GC candidates in NUV (FUV) identified by previous spectroscopic observations. On the basis of comparing our UV photometry to population models, we suggest that some of spectroscopically identified intermediate-age GCs may not be truly intermediate in age, but rather older GCs that possess developed HB stars which contribute to enhanced UV flux as well as Balmer lines.
