- ID:
- ivo://CDS.VizieR/J/A+A/544/A31
- Title:
- Star catalogues of Ptolemaios, Ulugh Beg
- Short Name:
- J/A+A/544/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In late antiquity and throughout the middle ages, the positions of stars on the celestial sphere were obtained from the star catalogue of Ptolemaios. A catalogue based on new measurements appeared in 1437, with positions by Ulugh Beg, and magnitudes from the 10th-century astronomer al-Sufi. We provide machine-readable versions of these two star catalogues, based on the editions by Toomer (1998) and Knobel (1917), and determine their accuracies by comparison with the modern Hipparcos Catalogue. The magnitudes in the catalogues correlate well with modern visual magnitudes; the indication `faint' by Ptolemaios is found to correspond to his magnitudes 5 and 6. Gaussian fits to the error distributions in longitude/latitude give widths sigma ~27-arcmin/23-arcmin in the range |{Delta}{lambda},{Delta}{beta}|<50-arcmin for Ptolemaios and {sigma}~22-arcmin/18-arcmin\ in Ulugh Beg. Fits to the range |{Delta}{lambda},{Delta}{beta}<100-arcmin gives 10-15 per cent larger widths, showing that the error distributions are broader than gaussians. The fraction of stars with positions wrong by more than 150-arcmin is about 2 per cent for Ptolemaios and 0.1 percent in Ulugh Beg; the numbers of unidentified stars are 1 in Ptolemaios and 3 in Ulugh Beg. These numbers testify to the excellent quality of both star catalogues (as edited by Toomer and Knobel).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/187/149
- Title:
- StarCAT: STIS UV echelle spectra of stars
- Short Name:
- J/ApJS/187/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- StarCAT is a catalog of high resolution ultraviolet spectra of objects classified as "stars," recorded by Space Telescope Imaging Spectrograph (STIS) during its initial seven years of operations (1997-2004). StarCAT is based on 3184 echelle observations of 545 distinct targets, with a total exposure duration of 5.2Ms. For many of the objects, broad ultraviolet coverage has been achieved by splicing echellegrams taken in two or more FUV (1150-1700{AA}) and/or NUV (1600-3100{AA}) settings. In cases of multiple pointings on conspicuously variable sources, spectra were separated into independent epochs. Otherwise, different epochs were combined to enhance the signal-to-noise ratio (S/N). A post-facto correction to the "calstis" pipeline data sets compensated for subtle wavelength distortions identified in a previous study of the STIS calibration lamps. An internal "fluxing" procedure yielded coherent spectral energy distributions (SEDs) for objects with broadly overlapping wavelength coverage. The best StarCAT material achieves 300m/s internal velocity precision; absolute accuracy at the 1km/s level; photometric accuracy of order 4%; and relative flux precision several times better (limited mainly by knowledge of SEDs of UV standard stars). While StarCAT represents a milestone in the large-scale post-processing of STIS echellegrams, a number of potential improvements in the underlying "final" pipeline are identified.
17753. Star cluster evolution
- ID:
- ivo://CDS.VizieR/J/A+A/321/29
- Title:
- Star cluster evolution
- Short Name:
- J/A+A/321/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A model of spectral evolution of star forming galaxies of various metallicity has been used to study the relation between the optical emission line ratio R_23_=([OII]{lambda}3727+[OIII]{lambda}{lambda}4959,5007)/H{beta} and the nebular oxygen abundance. It is shown that the scatter in an empirical comparison sample could be due to various upper stellar mass limits or different slopes of the stellar initial mass function in these objects.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A60
- Title:
- Star cluster formation in a tidal debris
- Short Name:
- J/A+A/628/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation. We study star cluster formation in a tidal debris - including the vicinity of three tidal dwarf galaxies - in a massive gas dominated collisional ring around NGC 5291. These dwarfs have physical parameters which differ significantly from local starbursting dwarfs. They are gas-rich, highly turbulent, have a gas metallicity already enriched up to half-solar, and are expected to be free of dark matter. The aim is to study massive star cluster formation in this as yet unexplored type of environment. We use imaging from the Hubble Space Telescope using broadband filters covering the wavelength range from the near- ultraviolet to the near-infrared. We determine the masses and ages of the cluster candidates by using the spectral energy distribution- fitting code CIGALE, carefully considering age-extinction degeneracy effects on the estimation of the physical parameters. Results. We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of about 40%, comparable to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they were formed at the very birth of the tidal dwarf galaxies and have survived for several hundred million years. Therefore our study shows that extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the young star clusters are not massive enough to survive for a Hubble time. However one may speculate that similar objects at higher redshift, with higher star formation rate, might form some of the long lived globular clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A13
- Title:
- Star cluster Gaia 1 stars equivalent widths
- Short Name:
- J/A+A/609/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star clusters, particularly those objects in the disk-bulge-halo interface are as yet poorly charted, despite the fact that they carry important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical abundance study of the recently discovered object Gaia 1. Photometry has previously suggested it as an intermediate-age, moderately metal-rich system, although the exact values for its age and metallicity remained ambiguous in the literature. We measured detailed chemical abundances of 14 elements in four red giant members, from high-resolution (R=25000) spectra that firmly establish Gaia 1 as an object associated with the thick disk. The resulting mean Fe abundance is -0.62+/-0.03(stat.)+/-0.10(sys.) dex, which is more metal-poor than indicated by previous spectroscopy from the literature, but it is fully in line with values from isochrone fitting. We find that Gaia 1 is moderately enhanced in the {alpha}-elements, which allowed us to consolidate its membership with the thick disk via chemical tagging. The cluster's Fe-peak and neutron-capture elements are similar to those found across the metal-rich disks, where the latter indicate some level of s-process activity. No significant spread in iron nor in other heavy elements was detected, whereas we find evidence of light-element variations in Na, Mg, and Al. Nonetheless, the traditional Na-O and Mg-Al (anti-)correlations, typically seen in old globular clusters, are not seen in our data. This confirms that Gaia 1 is rather a massive and luminous open cluster than a low-mass globular cluster. Finally, orbital computations of the target stars bolster our chemical findings of Gaia 1's present-day membership with the thick disk, even though it remains unclear which mechanisms put it in that place.
- ID:
- ivo://CDS.VizieR/J/A+A/501/949
- Title:
- Star cluster properties in five spiral galaxies
- Short Name:
- J/A+A/501/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aims: Our goal is to investigate the formation of star clusters in relatively unperturbed environments. To do this, we studied the five nearby spiral galaxies: NGC 45, NGC 1313, NGC 4395, NGC 5236, and NGC 7793. Methods: We obtained images of the galaxies and their star cluster systems in UBVI using the Advanced Camera for Surveys (ACS) and the Wide Field Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope. From a comparison of the broad-band colours with simple stellar population (SSP) models, we derived individual properties for each galaxy for the clusters such such as masses, ages, and sizes, as well as global star cluster system properties such as the age distribution, luminosity function, and disruption time for clusters. Results. We identified about 600 star cluster candidates in the five galaxies, typically spanning ages from 3.9Myr up to 1Gyr and masses from 10^2^M_{sun}_ up to 10^5^M_{sun}_. We used the cluster age distribution to reconstruct the recent star formation history of each galaxy and observed significant variations from galaxy to galaxy. We went on to derive the luminosity function of the young star clusters and found slopes around {alpha}~-2 (similar to the ones found in previous studies) and the brightest star cluster magnitudes consistent with a random sampling of the luminosity function without involving an upper luminosity cut off. Finally, the sample includes only a handful of old globular clusters in each galaxy from which we derive low globular cluster specific frequencies.
- ID:
- ivo://CDS.VizieR/VII/5A
- Title:
- Star Clusters and Associations, Selected Data
- Short Name:
- VII/5A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a selection of data on all open clusters extracted from the second, considerably enlarged edition of the "Catalogue of Star Clusters and Associations" edited by Alter, Balazs, and Ruprecht (1970), which includes four parts: Part 1: 1039 open clusters, five moving clusters, and 11 stellar groups; Part 2: 70 OB associations; Part 3: 125 globular clusters; Part 4: 28 extragalactic objects. The catalog includes galactic and equatorial coordinates, name, classification, angular diameter, distance, magnitude and spectral types of the brightest stars, total magnitude, and color excess.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A135
- Title:
- 35 star clusters and fields in the SMC
- Short Name:
- J/A+A/647/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we study 35 stellar clusters in the Small Magellanic Cloud (SMC) in order to provide their mean metallicities and ages. We also provide mean metallicities of the fields surrounding the clusters. We used Stroemgren photometry obtained with the 4.1 m SOAR telescope and take advantage of (b-y) and m1 colors for which there is a metallicity calibration presented in the literature. The spatial metallicity and age distributions of clusters across the SMC are investigated using the results obtained by Stroemgren photometry. We confirm earlier observations that younger, more metal-rich star clusters are concentrated in the central regions of the galaxy, while older, more metal-poor clusters are located farther from the SMC center. We construct the age-metallicity relation for the studied clusters and find good agreement with theoretical models of chemical enrichment, and with other literature age and metallicity values for those clusters. We also provide the mean metallicities for old and young populations of the field stars surrounding the clusters, and find the latter to be in good agreement with recent studies of the SMC Cepheid population. Finally, the Stroemgren photometry obtained for this study is made publicly available.
- ID:
- ivo://CDS.VizieR/J/AJ/157/12
- Title:
- Star clusters, associations, & candidates in the MW
- Short Name:
- J/AJ/157/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of Galactic star clusters, associations and candidates with 10978 entries. This multi-band catalog was constructed over 20 years, starting with visual inspections on the Digital Sky Survey and incremented with the 2MASS, WISE, VVV, Spitzer, and Herschel surveys. Large and small catalogs, as well as papers on individual objects have been systematically cross-identified. The catalog provides Galactic and equatorial coordinates, angular diameters, and chronologically ordered designations, making it simple to assign discoveries and verify how often the objects were cataloged by different authors, search methods, and/or surveys. Detection in a single band is the minimum constraint to validate an entry. About 3200 objects have measured parameters in the literature. A fundamental contribution of the present study is to present an additional ~7700 objects for the first analyses of nature, photometry, spectroscopy and structure. The present focus is not to compile or determine fundamental parameters, but to provide a catalog uniformly characterizing the entries. A major result is that now 4234 embedded clusters are cataloged, a factor of ~1.5 larger than open clusters. In addition to cross-identifications in different references and wavelength domains, we also communicate the discovery of 638 star clusters and similar objects. The present general catalog provides previously studied objects and thousands of additional entries in a homogeneous way, a timely contribution to Gaia-related works.
- ID:
- ivo://CDS.VizieR/VII/31B
- Title:
- Star Clusters/Associations. I. Associations
- Short Name:
- VII/31B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains data and bibliographical citations for all 70 associations of the second edition of the "Catalogue of Star Clusters and Associations (CSCA)" edited by Alter et al. (1970) which includes data for open clusters, associations, globular clusters and extragalactic objects up to 1967 and "Supplement to the CSCA" by Ruprecht et al. (1982), which contains the supplementary data up to the end of 1973. Thus, the literature is covered through 1973. The catalog includes the years of the literature, references, authors, abbreviated journal references, diameters, distances and color indices of the associations, number of stars and spectral types of the stars in the associations, and identification of the Palomar Observatory Sky Survey Chart on which the association appears.