Contents
Images
Upload your image
DSS Images Other Images
Related articles
The Radial Velocity Experiment (rave): Second Data Release
We present the second data release of the Radial Velocity Experiment(RAVE), an ambitious spectroscopic survey to measure radial velocitiesand stellar atmosphere parameters (temperature, metallicity, surfacegravity, and rotational velocity) of up to one million stars using the 6dF multi-object spectrograph on the 1.2 m UK Schmidt Telescope of theAnglo-Australian Observatory (AAO). The RAVE program started in 2003,obtaining medium resolution spectra (median R = 7500) in the Ca-tripletregion (8410-8795 Å) for southern hemisphere stars drawn from theTycho-2 and SuperCOSMOS catalogues, in the magnitude range 9 < I <12. Following the first data release, the current release doubles thesample of published radial velocities, now containing 51,829 radialvelocities for 49,327 individual stars observed on 141 nights between2003 April 11 and 2005 March 31. Comparison with external data setsshows that the new data collected since 2004 April 3 show a standarddeviation of 1.3 km s–1, about twice as good as for thefirst data release. For the first time, this data release containsvalues of stellar parameters from 22,407 spectra of 21,121 individualstars. They were derived by a penalized χ2 method usingan extensive grid of synthetic spectra calculated from the latestversion of Kurucz stellar atmosphere models. From comparison withexternal data sets, our conservative estimates of errors of the stellarparameters for a spectrum with an average signal-to-noise ratio (S/N) of~40 are 400 K in temperature, 0.5 dex in gravity, and 0.2 dex inmetallicity. We note however that, for all three stellar parameters, theinternal errors estimated from repeat RAVE observations of 855 stars areat least a factor 2 smaller. We demonstrate that the results show nosystematic offsets if compared to values derived from photometry orcomplementary spectroscopic analyses. The data release includes propermotions from Starnet2, Tycho-2, and UCAC2 catalogs and photometricmeasurements from Tycho-2 USNO-B, DENIS, and 2MASS. The data release canbe accessed via the RAVE Web site: http://www.rave-survey.org andthrough CDS.
| Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters
We present a homogeneous set of stellar atmospheric parameters(Teff, logg, [Fe/H]) for MILES, a new spectral stellarlibrary covering the range λλ 3525-7500Å at2.3Å (FWHM) spectral resolution. The library consists of 985 starsspanning a large range in atmospheric parameters, from super-metal-rich,cool stars to hot, metal-poor stars. The spectral resolution, spectraltype coverage and number of stars represent a substantial improvementover previous libraries used in population synthesis models. Theatmospheric parameters that we present here are the result of aprevious, extensive compilation from the literature. In order toconstruct a homogeneous data set of atmospheric parameters we have takenthe sample of stars of Soubiran, Katz & Cayrel, which has very welldetermined fundamental parameters, as the standard reference system forour field stars, and have calibrated and bootstrapped the data fromother papers against it. The atmospheric parameters for our clusterstars have also been revised and updated according to recent metallicityscales, colour-temperature relations and improved set of isochrones.
| Medium-resolution Isaac Newton Telescope library of empirical spectra
A new stellar library developed for stellar population synthesismodelling is presented. The library consists of 985 stars spanning alarge range in atmospheric parameters. The spectra were obtained at the2.5-m Isaac Newton Telescope and cover the range λλ3525-7500 Å at 2.3 Å (full width at half-maximum) spectralresolution. The spectral resolution, spectral-type coverage,flux-calibration accuracy and number of stars represent a substantialimprovement over previous libraries used in population-synthesis models.
| Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| Statistical cataloging of archival data for luminosity class IV-V stars. II. The epoch 2001 [Fe/H] catalog
This paper describes the derivation of an updated statistical catalog ofmetallicities. The stars for which those metallicities apply are ofspectral types F, G, and K, and are on or near the main sequence. Theinput data for the catalog are values of [Fe/H] published before 2002February and derived from lines of weak and moderate strength. Theanalyses used to derive the data have been based on one-dimensional LTEmodel atmospheres. Initial adjustments which are applied to the datainclude corrections to a uniform temperature scale which is given in acompanion paper (see Taylor \cite{t02}). After correction, the data aresubjected to a statistical analysis. For each of 941 stars considered,the results of that analysis include a mean value of [Fe/H], an rmserror, an associated number of degrees of freedom, and one or moreidentification numbers for source papers. The catalog of these resultssupersedes an earlier version given by Taylor (\cite{t94b}).Catalog is only available in electronic form at the CDS via anonymousftp cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/731
| Statistical cataloging of archival data for luminosity class IV-V stars. I. The epoch 2001 temperature catalog
This paper is one of a pair in which temperatures and metallicitycatalogs for class IV-V stars are considered. The temperature catalogdescribed here is derived from a calibration based on stellar angulardiameters. If published calibrations of this kind are compared by usingcolor-index transformations, temperature-dependent differences among thecalibrations are commonly found. However, such differences are minimizedif attention is restricted to calibrations based on Johnson V-K. Acalibration of this sort from Di Benedetto (\cite{dib98}) is thereforetested and adopted. That calibration is then applied to spectroscopicand photometric data, with the latter predominating. Cousins R-Iphotometry receives special attention because of its high precision andlow metallicity sensitivity. Testing of temperatures derived from thecalibration suggests that their accuracy and precision are satisfactory,though further testing will be warranted as new results appear. Thesetemperatures appear in the catalog as values of theta equiv5040/T(effective). Most of these entries are accompanied by measured orderived values of Cousins R-I. Entries are given for 951 stars.Catalog is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/721
| 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
| Classification of Population II Stars in the Vilnius Photometric System. I. Methods
The methods used for classification of Population II stars in theVilnius photometric system are described. An extensive set of standardswith known astrophysical parameters compiled from the literature sourcesis given. These standard stars are classified in the Vilnius photometricsystem using the methods described. The accuracy of classification isevaluated by a comparison of the astrophysical parameters derived fromthe Vilnius photometric system with those estimated from spectroscopicstudies as well as from photometric data in other systems. For dwarfsand subdwarfs, we find a satisfactory agreement between our reddeningsand those estimated in the uvbyscriptstyle beta system. The standarddeviation of [Fe/H] deter mined in the Vilnius system is about 0.2 dex.The absolute magnitude for dwarfs and subdwarfs is estimated with anaccuracy of scriptstyle <=0.5 mag.
| Analyses of archival data for cool dwarfs. 2: A catalog of temperatures
A calibration presented in a previous paper is used in this paper toderive temperatures for FGK stars near the main sequence. Thecalibration is checked against published counterparts, and it is foundthat previous calibrations have not established K-dwarf temperatures inparticular beyond reasonable doubt. The database assembled to derive thetemperatures is described, and the problems posed by close binaries areevaluated. The newly derived temperatures are used to check a line-depthratio proposed as a thermometer by Gray and Johanson (1991, PASP, 103,439), and it is found that the ratio is metallicity-sensitive.Temperatures are given for a total of 417 stars.
| 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.
| Three-dimensional classification of 78 metal-deficient giants in the Vinius photometric system
Not Available
| Photoelectric photometry of metal-deficient giants of spectral types G and K in the Vilnius system
Not Available
| Population studies. I - The Bidelman-MacConnell 'weak-metal' stars
BRVI and DDO photometry are presented for 309 Bidelman-MacConnell'weak-metal' stars. Radial velocities are calculated for most of thestars having Fe/H abundances of no more than -0.8. The photometricobservations were carried out using the 0.6-meter and 1.0-metertelescopes of the Siding Spring Observatory. Photometric taxonomy wasused to classify the stars as dwarfs, giants, red-horizontal branchstars, and ultraviolet-bright stars, respectively. It is found that 35percent of the stars are giants; 50 percent are dwarfs; and 5 percentbelong to the red-horizontal branch group. The role of selection effectsin investigations of the formation of the Galaxy is discussed on thebasis of the photometric observations and the observational constraintsproposed by Eggen et al. (1962).
| A catalogue of Fe/H determinations, 1984 edition
The present version of the Cayrel de Strobel et al. (1981) catalog ofFe/H abundance ratio determinations contains 1921 values for 1035 stars,which represents an augmentation over the previous publication of 48 and47 percent, respectively. In addition, the literature search conductedis complete up to December, 1983. Stellar metal abundance, effectivetemperature, spectroscopic gravity, spectral type, and photometricindices are covered.
| H-alpha emission in old giants
New data on H-alpha emission in 24 globular cluster giants are combinedwith similar published data on H-alpha emission in globular cluster,open cluster and field halo giants, making a total homogeneous sample of113 old giants. On the basis of this sample, the most relevantconclusions are: (i) at the resolving power of the CTIO and KPNO echellespectrographs, no star with a luminosity log(L/solar L) less than 2.7has H-alpha emission; (ii) the fraction of stars brighter than log(L/solar L) = 2.7 exhibiting H-alpha emission at this spectralresolution is 0.61 + or - 0.09; this fraction is only weakly dependenton luminosity; (iii) the clusters with red horizontal branches containvery few stars with H-alpha emission wings; and (iv) for other clusters,H-alpha emission may be marginally favored by a higher metallicityand/or microturbulence.
| Metal-Deficient Giants in the Galactic Field - Catalogue and Some Physical Parameters
Not Available
| Abundances in metal-poor stars. III - Eleven field giants
The present investigation is concerned with the high dispersion spectraof eleven field giants, covering a metallicity range from -0.4 to -2.5(Fe abundances). The data provide a basis for comparing the compositionof globular clusters and field stars over a wide range in metalabundance. The kinematical and dynamical properties of the stars suggesta halo origin. Two samples of halo stars are compared. It appears thatCa and Ti are overabundant in metal-poor field stars both in globularclusters and in the field halo. However, the globular clusters aresystematically richer in these elements than field stars. Ba (andperhaps Na and Mg) seems overdeficient in metal-poor stars in the fieldhalo but not in globular clusters.
| H-alpha emission and mass loss from metal-poor giants
H-alpha emission lines are studied by means of high dispersion spectraof about 30 metal-poor giants. No emission line has been found in starshaving a luminosity less than log (L/solar-L) = 2.7, while 2/3 of thestars brighter than that show emission lines. From the data H-alphaemission seems correlated with metal abundance and microturbulence. Someimplications about mass loss from these stars are briefly considered.
| Photometry of Metal Weak Stars
Not Available
| Southern subdwarf photometry
UBV photometry and normalized UV excesses are reported for 176 southernmetal-poor stars selected from the objective-prism survey of Bidelmanand MacConnell (1973) as well as 49 other metal-deficient starsidentified in other surveys. Photometry is also presented for 32 otherstars lying near the 225 program stars (although not explicitlyidentified as such in the text, the program stars are apparentlysubdwarfs and subdwarf candidates). Previously determined spectral typesand degrees of line weakening are given for the 225 stars, andmetallicities are estimated on the basis of the degrees of lineweakening. It is noted that 33 F and G stars with extreme meannormalized UV excesses of approximately 0.22 mag have a mean Fe/H valueof -1.4 and probably represent halo subdwarfs, while 82 F and G starswith moderate UV excesses are mostly old disk stars.
| A Search for Metal-Deficient Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...22..117B&db_key=AST
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Sagittarius |
| Right ascension: | 20h04m49.47s |
| Declination: | -28°16'25.1" |
| Apparent magnitude: | 9.558 |
| Proper motion RA: | 2.5 |
| Proper motion Dec: | 47 |
| B-T magnitude: | 10.131 |
| V-T magnitude: | 9.606 |
Catalogs and designations:
|
INHABITED SKY
