Masses of Star Clusters in the Nuclei of Bulgeless Spiral Galaxies
In the last decade star clusters have been found in the centers ofspiral galaxies across all Hubble types. We here present a spectroscopicstudy of the exceptionally bright (106-108Lsolar) but compact (re~5 pc) nuclear starclusters in very late type spirals with the Ultraviolet and VisualEchelle Spectrograph at the VLT. We find that the velocity dispersionsof the nine clusters in our sample range from 13 to 34 kms-1. Using photometric data from the Hubble Space TelescopeWFPC2 and spherically symmetric dynamical models, we determine massesbetween 8×105 and 6×107Msolar. The mass-to-light ratios range from 0.2 to 1.5 in theI band. This indicates a young mean age for most clusters, in agreementwith previous studies. Given their high masses and small sizes, we findthat nuclear clusters are among the objects with the highest meansurface density known (up to 105 Msolarpc-2). From their dynamical properties we infer that, ratherthan small bulges, the closest structural kin of nuclear clusters appearto be massive compact star clusters. This includes such differentobjects as globular clusters, ``super star clusters,'' ultracompactdwarf galaxies (UCDs), and the nuclei of dwarf elliptical galaxies. Itis a challenge to explain why, despite the widely different currentenvironments, all different types of massive star clusters share verysimilar and structural properties. A possible explanation links UCDs andmassive globular clusters to nuclear star clusters through stripping ofnucleated dwarf galaxies in a merger event. The extreme properties ofthis type of cluster would then be a consequence of the clusters'location in the centers of their respective host galaxies.
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Statistical Constraints for Astrometric Binaries with Nonlinear Motion
Useful constraints on the orbits and mass ratios of astrometric binariesin the Hipparcos catalog are derived from the measured proper motiondifferences of Hipparcos and Tycho-2 (Δμ), accelerations ofproper motions (μ˙), and second derivatives of proper motions(μ̈). It is shown how, in some cases, statistical bounds can beestimated for the masses of the secondary components. Two catalogs ofastrometric binaries are generated, one of binaries with significantproper motion differences and the other of binaries with significantaccelerations of their proper motions. Mathematical relations betweenthe astrometric observables Δμ, μ˙, and μ̈ andthe orbital elements are derived in the appendices. We find a remarkabledifference between the distribution of spectral types of stars withlarge accelerations but small proper motion differences and that ofstars with large proper motion differences but insignificantaccelerations. The spectral type distribution for the former sample ofbinaries is the same as the general distribution of all stars in theHipparcos catalog, whereas the latter sample is clearly dominated bysolar-type stars, with an obvious dearth of blue stars. We point outthat the latter set includes mostly binaries with long periods (longerthan about 6 yr).
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A catalog of bright calibrator stars for 200-m baseline near-infrared stellar interferometry
We present in this paper a catalog of reference stars suitable forcalibrating infrared interferometric observations. In the K band,visibilities can be calibrated with a precision of 1% on baselines up to200 meters for the whole sky, and up to 300 meters for some part of thesky. This work, extending to longer baselines a previous catalogcompiled by Bordé et al. (2002, A&A, 393, 183), isparticularl y well adapted to hectometric-class interferometers such asthe Very Large Telescope Interferometer (VLTI, Glindemann et al. 2003,Proc. SPIE, 4838, 89) or the CHARA array (ten Brummelaar et al. 2003,Proc. SPIE, 4838, 69) when one is observing well-resolved, high-surfacebrightness objects (K 8). We use the absolute spectro-photometriccalibration method introduced by Cohen et al. (1999, AJ, 117, 1864) toderive the angular diameters of our new set of 948 G8-M0 calibratorstars extracted from the IRAS, 2MASS and MSX catalogs. Angular stellardiameters range from 0.6 mas to 1.8 mas (median is 1.1 mas) with amedian precision of 1.35%. For both the northern and southernhemispheres, the closest calibrator star is always less than 10°away.
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CHARM2: An updated Catalog of High Angular Resolution Measurements
We present an update of the Catalog of High Angular ResolutionMeasurements (CHARM, Richichi & Percheron \cite{CHARM}, A&A,386, 492), which includes results available until July 2004. CHARM2 is acompilation of direct measurements by high angular resolution methods,as well as indirect estimates of stellar diameters. Its main goal is toprovide a reference list of sources which can be used for calibrationand verification observations with long-baseline optical and near-IRinterferometers. Single and binary stars are included, as are complexobjects from circumstellar shells to extragalactic sources. The presentupdate provides an increase of almost a factor of two over the previousedition. Additionally, it includes several corrections and improvements,as well as a cross-check with the valuable public release observationsof the ESO Very Large Telescope Interferometer (VLTI). A total of 8231entries for 3238 unique sources are now present in CHARM2. Thisrepresents an increase of a factor of 3.4 and 2.0, respectively, overthe contents of the previous version of CHARM.The catalog is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/431/773
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Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
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The proper motions of fundamental stars. I. 1535 stars from the Basic FK5
A direct combination of the positions given in the HIPPARCOS cataloguewith astrometric ground-based catalogues having epochs later than 1939allows us to obtain new proper motions for the 1535 stars of the BasicFK5. The results are presented as the catalogue Proper Motions ofFundamental Stars (PMFS), Part I. The median precision of the propermotions is 0.5 mas/year for mu alpha cos delta and 0.7mas/year for mu delta . The non-linear motions of thephotocentres of a few hundred astrometric binaries are separated intotheir linear and elliptic motions. Since the PMFS proper motions do notinclude the information given by the proper motions from othercatalogues (HIPPARCOS, FK5, FK6, etc.) this catalogue can be used as anindependent source of the proper motions of the fundamental stars.Catalogue (Table 3) is only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strastg.fr/cgi-bin/qcat?J/A+A/365/222
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Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
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Second astrolabe catalogue of Santiago.
Positions for 350 FK5 and 164 FK5 Extension stars as determined with theDanjon astrolabe of Santiago and differences astrolabe-catalogue aregiven for Equinox J2000.0 and for the mean observation epoch of eachstar. The average mean error in alpha is +/-0.005s and +/-0.07" indelta. The mean epoch of observation of the catalogue is J1979.96.
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Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
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Santiago Fundamental Catalogue - A catalogue of 1105 FK5 stars (equinox J2000.0)
The positions in right ascension and declination of 1105 FK5 stars,observed with a Meridian Circle during the period 1979 to 1991, aregiven. The average mean square error of a position, for the wholecatalog, is +/- 0.009 s in right ascension and +/- 0.10 arcsec indeclination. The mean epoch of the catalog is 1983.148.
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Secondary standards for H-beta photometry in the Southern Hemisphere (second series).
Not Available
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Physical data of the fundamental stars.
Not Available
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UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available
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Large and kinematically unbiased samples of G- and K-type stars. IV - Evolved stars of the old disk population
Modified Stromgren and (R,I) photometry, along with DDO and Genevaphotometry, are presented for a complete sample of evolved old-disk Gand K giants in the Bright Star Catalogue. Stars with ages of between1.5 x 10 to the 9th and 10 to the 10th yr are found to have anear-normal distribution of heavy element abundances, centered on anFe/H abundance ratio of -0.1 dex. The old disk clusters NGC 3680 and IC4651 contain red-straggler young-disk giants that are probablycontemporaries of the blue stragglers in the clusters.
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Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
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Secondary standards for the Stromgren UVBY system
Observations of 158 E region stars have been made in the Stromgrensystem, using the 46-cm reflector at Cape Town. They are mostly brighterthan eighth magnitude and are intended for use as secondary standardsfor the four-color system. The E region relative zero points are definedwith a precision of + or - 0.001 mag, and the internal standard errorsof the colors life between + or - 0.001 and + or - 0.002 mag.
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Santiago declination catalogue - A declination catalogue of 412 FK4 stars (equinox 1950.0)
This catalog contains the positions in declination, of 412 FK4 stars.The observations were carried out with the Repsold Meridian Circle atCerro Calan National Astronomical Observatory, during the period1963-1968. The average mean square error of one observation (for thewhole catalog) is + or - 0.13 arcsec. The mean epoch of observation ofthe catalog is 1965.75.
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UBV photometry of E region standard stars of intermediate brightness
Photometry data are given for 335 stars in the nine E regions.Observations were made using a photometer and filters on the 47 cmreflector at Cape Town. The stellar dispersions are summarized. Data arepresented in tabular form.
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The Wolf 630 moving group of stars
An analysis is made of the probability of collective membership of thestars assigned by Eggen to the Wolf 630 moving group. This probabilityis estimated from the scatter of points in the color-absolute magnitudediagram when compared to the intrinsic scatter observed for M67.Particular attention is paid to the random errors for all the observedand deduced stellar parameters. Results show that either theobservational errors must be about 2.4 times larger than given in theproper motion and radial velocity source catalogues, or the intrinsicscatter in the color-magnitude diagram for the Wolf 630 group must bemuch larger than for M67, or many of the stars considered cannot bemembers.
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DDO Observations of Southern Stars
Not Available
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Up-To UBVRI Values for the E-Region Standard Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...46....7V&db_key=AST
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Photometric standard stars for the UBV and (RI)KC systems.
Not Available
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Fainter Standards for VRI Photometry in the E Regions
Not Available
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A photoelectric measurement of magnesium for late-type stars
A photoelectric index of MgH + Mg b for late-type stars has been createdby the addition of one filter bandpass to the DDO system. Measurementsshow that this index has good sensitivity to surface gravity for Kstars, and suggest that it can differentiate metal-poor halo giants fromdisk stars. From this index, involving measurement through two filtersalone, it appears that membership can be determined for stars on thegiant branch of globular clusters. It is possible that the index couldbe used, after calibration with cluster giants, to determine ages ofgiant stars in the field.
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Catalogue general des etoiles observees a l'astrolabe (1957-1975), corrections individuelles aux positions DU FK4.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&AS...31..159B&db_key=AST
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VRI standards in the E regions
Not Available
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Luminosity functions and the evolution of low-mass population I giants
Luminosity functions in terms of bolometric magnitudes are constructedfor M67 and for two samples of old-disk field giants. These are comparedwith theoretical rates of evolution on the giant branch. M67 has too fewstars to give a useful comparison. The field giants show good agreementwith theory, and the number of stars at the 'clump' suggests that corehelium-burning is prolonged by overshoot with semiconvective mixing. Thefuel consumption derived from the luminosity functions is consistentwith core helium ignition at the theoretically predicted core mass, andwith a final core mass in agreement with observed white dwarf masses.Data are needed for a larger complete sample of field giants for theluminosity function to be better determined. Further details, especiallyfor the variable M giants at the top of the giant branch, are needed forpopulation syntheses of elliptical galaxies.
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DDO intermediate-band photometry of moving-group stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975PASP...87...17B&db_key=AST
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Standard Stars for VRI Photometry with S25 Response Photocathodes [Errata: 1974MNSSA..33....1C]
Not Available
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Investigation of a Milky Way field in Canis Major
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79.1022C&db_key=AST
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INHABITED SKY
