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Dynamical mass estimates for two luminous star clusters in galactic merger remnants
We present high-dispersion spectra of two extremely massive starclusters in galactic merger remnants, obtained using the UVESspectrograph mounted on the ESO Very Large Telescope. One cluster, W30,is located in the ~500 Myr old merger remnant NGC 7252 and has avelocity dispersion and effective radius of σ=27.5±2.5 kms-1 and Reff=9.3±1.7 pc, respectively. Theother cluster, G114, located in the ~3 Gyr old merger remnant NGC 1316,is much more compact, Reff=4.08±0.55 pc, and has avelocity dispersion of σ=42.1±2.8 km s-1. Thesemeasurements allow an estimate of the virial mass of the two clusters,yielding Mdyn(W30)=1.59(±0.26)× 10^7Mȯ and Mdyn(G114)=1.64(±0.13)×10^7 Mȯ. Both clusters are extremely massive, being morethan three times heavier than the most massive globular clusters in theGalaxy. For both clusters we measure light-to-mass ratios, which whencompared to simple stellar population (SSP) models of the appropriateage, are consistent with a Kroupa-type stellar mass function. Usingmeasurements from the literature we find a strong age dependence on howwell SSP models (with underlying Kroupa or Salpeter-type stellar massfunctions) fit the light-to-mass ratio of clusters. Based on this resultwe suggest that the large scatter in the light-to-mass ratio of theyoungest clusters is not due to variations in the underlying stellarmass function, but instead to the rapidly changing internal dynamics ofyoung clusters. Based on sampling statistics we argue that while W30 andG114 are extremely massive, they are consistent with being the mostmassive clusters formed in a continuous power-law cluster massdistribution. Finally, based on the positions of old globular clusters,young massive clusters (YMCs), ultra-compact dwarf galaxies (UCDs) anddwarf-globular transition objects (DGTOs) in κ-space we concludethat 1) UCDs and DGTOs are consistent with the high mass end of starclusters and 2) YMCs occupy a much larger parameter space than oldglobular clusters, consistent with the idea of preferential disruptionof star clusters.
| Catalogue of [Fe/H] determinations for FGK stars: 2001 edition
The catalogue presented here is a compilation of published atmosphericparameters (Teff, log g, [Fe/H]) obtained from highresolution, high signal-to-noise spectroscopic observations. This newedition has changed compared to the five previous versions. It is nowrestricted to intermediate and low mass stars (F, G and K stars). Itcontains 6354 determinations of (Teff, log g, [Fe/H]) for3356 stars, including 909 stars in 79 stellar systems. The literature iscomplete between January 1980 and December 2000 and includes 378references. The catalogue is made up of two tables, one for field starsand one for stars in galactic associations, open and globular clustersand external galaxies. The catalogue is distributed through the CDSdatabase. Access to the catalogue with cross-identification to othersets of data is also possible with VizieR (Ochsenbein et al.\cite{och00}). The catalogue (Tables 1 and 2) is only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/373/159 and VizieRhttp://vizier.u-strasbg.fr/.
| A catalogue of [Fe/H] determinations: 1996 edition
A fifth Edition of the Catalogue of [Fe/H] determinations is presentedherewith. It contains 5946 determinations for 3247 stars, including 751stars in 84 associations, clusters or galaxies. The literature iscomplete up to December 1995. The 700 bibliographical referencescorrespond to [Fe/H] determinations obtained from high resolutionspectroscopic observations and detailed analyses, most of them carriedout with the help of model-atmospheres. The Catalogue is made up ofthree formatted files: File 1: field stars, File 2: stars in galacticassociations and clusters, and stars in SMC, LMC, M33, File 3: numberedlist of bibliographical references The three files are only available inelectronic form at the Centre de Donnees Stellaires in Strasbourg, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
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Pozíciós és asztrometriai adatok
| Csillagkép: | Sas |
| Rektaszcenzió: | 22h25m31.07s |
| Deklináció: | -11°54'28.9" |
| Vizuális fényesség: | 8.589 |
| Távolság: | 840.336 parszek |
| RA sajátmozgás: | -4.5 |
| Dec sajátmozgás: | 1 |
| B-T magnitude: | 8.855 |
| V-T magnitude: | 8.611 |
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