Upload your image
DSS Images Other Images
Submit a new article
|Abundances of Baade's Window Giants from Keck HIRES Spectra. I. Stellar Parameters and [Fe/H] Values|
We present the first results of a new abundance survey of the Milky Waybulge based on Keck HIRES spectra of 27 K giants in the Baade's Window(l=1deg, b=-4deg) field. The spectral data used inthis study are of much higher resolution and signal-to-noise ratio thanprevious optical studies of Galactic bulge stars. The [Fe/H] values ofour stars, which range between -1.29 and +0.51, were used to recalibratelarge low-resolution surveys of bulge stars. Our best value for the mean[Fe/H] of the bulge is -0.10+/-0.04. This mean value is similar to themean metallicity of the local disk and indicates that there cannot be astrong metallicity gradient inside the solar circle. The metallicitydistribution of stars confirms that the bulge does not suffer from theso-called G dwarf problem. This paper also details the new abundancetechniques necessary to analyze very metal-rich K giants, including anew Fe line list and regions of low blanketing for continuumidentification.Based on data obtained at the W. M. Keck Observatory, which is operatedas a scientific partnership among the California Institute ofTechnology, the University of California, and NASA and was made possibleby the generous financial support of the W. M. Keck Foundation.
|Adaptive Optics Photometry and Astrometry of Binary Stars|
We present astrometric and photometric measurements of 39 binary starsmade with the adaptive optics system on the 3.6 m AdvancedElectro-Optical System (AEOS) telescope, taken from 2002 November to2003 March. The binaries have separations ranging from 0.08" to 5.11"and differential magnitudes ranging from 0.096 to 7.9. Also, we includea list of observations of 23 known binaries that we were unable toresolve. In the process of these measurements, we discovered three newcompanions to two previously known binary stars. We also discuss theeffects of scintillation and anisoplanatism on measurements of binarystar photometry in adaptive optics images. Suggestions on how tominimize these effects are then given.Based on observations made at the Maui Space Surveillance Systemoperated by Detachment 15 of the US Air Force Research Laboratory'sDirected Energy Directorate.
|First results from the ESO VLTI calibrators program|
The ESO Very Large Telescope Interferometer (VLTI) is one of the leadinginterferometric facilities. It is equipped with several 8.2 and 1.8 mtelescopes, a large number of baselines up to 200 m, and with severalsubsystems designed to enable high quality measurements and to improvesignificantly the limits of sensitivities currently available tolong-baseline interferometry. The full scientific potential of the VLTIcan be exploited only if a consistent set of good quality calibrators isavailable. For this, a large number of observations of potentialcalibrators have been obtained during the commissioning phase of theVLTI. These data are publicly available. We briefly describe theinterferometer, the VINCI instrument used for the observations, the dataflow from acquisition to processed results, and we present and commenton the volume of observations gathered and scrutinized. The result is alist of 191 calibrator candidates, for which a total of 12 066observations can be deemed of satisfactory quality. We present a generalstatistical analysis of this sample, using as a starting point theangular diameters previously available in the literature. We derive thegeneral characteristics of the VLTI transfer function, and its trendwith time in the period 2001 through mid-2004. A second paper will bedevoted to a detailed investigation of a selected sample, aimed atestablishing a VLTI-based homogeneous system of calibrators.
|Measuring starspots on magnetically active stars with the VLTI|
We present feasibility studies to directly image stellar surfacefeatures, which are caused by magnetic activity, with the Very LargeTelescope Interferometer (VLTI). We concentrate on late typemagnetically active stars, for which the distribution of starspots onthe surface has been inferred from photometric and spectroscopic imaginganalysis. The study of the surface spot evolution during consecutiverotation cycles will allow first direct measurements (apart from theSun) of differential rotation which is the central ingredient ofmagnetic dynamo processes. The VLTI will provide baselines of up to 200m, and two scientific instruments for interferometric studies at near-and mid-infrared wavelengths. Imaging capabilities will be made possibleby closure-phase techniques. We conclude that a realistically modeledcool surface spot can be detected on stars with angular diametersexceeding ~ 2 mas using the VLTI with the first generation instrumentAMBER. The spot parameters can then be derived with reasonable accuracy.We discuss that the lack of knowledge of magnetically active stars ofthe required angular size, especially in the southern hemisphere, is acurrent limitation for VLTI observations of these surface features.
|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 (184.108.40.206) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
|Dating Ptolemy's star catalogue through proper motions : the Hipparchan epoch.|
|Keck Mid-Infrared Imaging of QSO 2237+0305|
Using the Long Wavelength Spectrometer on Keck, we have imaged thegravitationally lensed radio-quiet quasi-stellar object QSO 2237+0305 at8.9 and 11.7 μm for the first time. The mid-IR flux ratios areinconsistent with the optical flux ratios but agree with the radio fluxratios and with some published gravitational lens models. These fluxratios indicate that the IR emission is not affected by microlensing,which rules out the synchrotron emission model. The IR emission islikely produced by hot dust extended on a length scale of more than 0.03pc. The spectral energy distribution further implies a narrow range ofdust temperatures, suggesting that the dust may be located in a shellextending between ~1 and 3 pc from the nucleus and intercepting abouthalf of the QSO luminosity.
|Two-colour photometry for 9473 components of close Hipparcos double and multiple stars|
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
|Revision and Calibration of MK Luminosity Classes for Cool Giants by HIPPARCOS Parallaxes|
The Hipparcos parallaxes of cool giants are utilized in two ways in thispaper. First, a plot of reduced parallaxes of stars brighter than 6.5,as a function of spectral type, for the first time separates members ofthe clump from stars in the main giant ridge. A slight modification ofthe MK luminosity standards has been made so that luminosity class IIIbdefines members of the clump, and nearly all of the class III stars fallwithin the main giant ridge. Second, a new calibration of MK luminosityclasses III and IIIb in terms of visual absolute magnitudes has beenmade.
|A Second Catalog of Orbiting Astronomical Observatory 2 Filter Photometry: Ultraviolet Photometry of 614 Stars|
Ultraviolet photometry from the Wisconsin Experiment Package on theOrbiting Astronomical Observatory 2 (OAO 2) is presented for 614 stars.Previously unpublished magnitudes from 12 filter bandpasses withwavelengths ranging from 1330 to 4250 Å have been placed on thewhite dwarf model atmosphere absolute flux scale. The fluxes wereconverted to magnitudes using V=0 for F(V)=3.46x10^-9 ergs cm^-2 s^-1Å^-1, or m_lambda=-2.5logF_lambda-21.15. This second catalogeffectively doubles the amount of OAO 2 photometry available in theliterature and includes many objects too bright to be observed withmodern space observatories.
|Catalogs of temperatures and [Fe/H] averages for evolved G and K stars|
A catalog of mean values of [Fe/H] for evolved G and K stars isdescribed. The zero point for the catalog entries has been establishedby using differential analyses. Literature sources for those entries areincluded in the catalog. The mean values are given with rms errors andnumbers of degrees of freedom, and a simple example of the use of thesestatistical data is given. For a number of the stars with entries in thecatalog, temperatures have been determined. A separate catalogcontaining those data is briefly described. Catalog only available atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|Dark matter in early-type spiral galaxies: the case of NGC 2179 and of NGC 2775|
We present the stellar and ionized-gas velocity curves andvelocity-dispersion profiles along the major axis for six early-typespiral galaxies. Two of these galaxies, namely NGC 2179 and NGC 2775,are particularly suited for the study of dark matter halos. Using theirluminosity profiles and modeling their stellar and gaseous kinematics,we derive the mass contributions of the luminous and the dark matter tothe total potential. In NGC 2179 we find that the data (measured out toabout the optical radius R_opt) unambiguously require the presence of amassive dark halo. For the brighter and bigger object NGC 2775, we canrule out a significant halo contribution at radii R <~ 0.6 R_opt.Although preliminary, these results agree with the familiar massdistribution trend known for late-type spirals of comparable mass. Basedon observations carried out at ESO, La Silla (Chile) (ESO N. 52, 1-020)and on observations obtained with the VATT: the Alice P. LennonTelescope and the Thomas J. Bannan Astrophysics Facility. Tables 4 to 42are only available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (18.104.22.168) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.
|Determination of the temperatures of selected ISO flux calibration stars using the Infrared Flux Method|
Effective temperatures for 420 stars with spectral types between A0 andK3, and luminosity classes between II and V, selected for a fluxcalibration of the Infrared Space Observatory, ISO, have been determinedusing the Infrared Flux Method (IRFM). The determinations are based onnarrow and wide band photometric data obtained for this purpose, andtake into account previously published narrow-band measures oftemperature. Regression coefficients are given for relations between thedetermined temperatures and the photometric parameters (B2-V1), (b-y)and (B-V), corrected for interstellar extinction through use ofHipparcos parallaxes. A correction for the effect of metallicity on thedetermination of integrated flux is proposed. The importance of aknowledge of metallicity in the representation of derived temperaturesfor Class V, IV and III stars by empirical functions is discussed andformulae given. An estimate is given for the probable error of eachtemperature determination. Based on data from the ESA HipparcosAstrometry Satellite.
|Infrared standards for ISO. I. A new calibration of mid infrared photometry|
We present N, 8.7 mu m, 9.8 mu m 12.5 mu m and Q bolometry of 26 starswhich were observed on the IRTF. These are primarily K giants which havebeen well measured at other wavelengths and are chosen to be single andnon-variable. Hence the data presented provides a new homogeneous set ofmid IR standards. As a test of part of the calibration strategy of ISOover this wavelength range, the zero points have been set using theKurucz model grids (1993) to predict the mid IR magnitudes from near IRdata. An analysis of the errors involved is presented and a comparisonwith more direct methods for the determination of the zero pointssuggest an possible error of 0.015 mags, although the source of thiserror is unclear as it is at the level of the uncertainty in the moredirect methods. The effect of the SiO fundamental on the spectral energydistributions of K giants is discussed.
|The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants|
We present X-ray data for all late-type (A, F, G, K, M) giants andsupergiants (luminosity classes I to III-IV) listed in the Bright StarCatalogue that have been detected in the ROSAT all-sky survey.Altogether, our catalogue contains 450 entries of X-ray emitting evolvedlate-type stars, which corresponds to an average detection rate of about11.7 percent. The selection of the sample stars, the data analysis, thecriteria for an accepted match between star and X-ray source, and thedetermination of X-ray fluxes are described. Catalogue only available atCDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|Classification and Identification of IRAS Sources with Low-Resolution Spectra|
IRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed.
|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 (126.96.36.199), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|The Pulkovo Spectrophotometric Catalog of Bright Stars in the Range from 320 TO 1080 NM|
A spectrophotometric catalog is presented, combining results of numerousobservations made by Pulkovo astronomers at different observing sites.The catalog consists of three parts: the first contains the data for 602stars in the spectral range of 320--735 nm with a resolution of 5 nm,the second one contains 285 stars in the spectral range of 500--1080 nmwith a resolution of 10 nm and the third one contains 278 stars combinedfrom the preceding catalogs in the spectral range of 320--1080 nm with aresolution of 10 nm. The data are presented in absolute energy unitsW/m(2) m, with a step of 2.5 nm and with an accuracy not lower than1.5--2.0%.
|A Study of Variability in a Sample of G and K Giants|
Eight years of Ca II surface activity records from Mount WilsonObservatory measured for 12 bright G-K III stars have been analyzed inorder to detect periodic variations attributable to rotation. We alsopresent photometric V-band data for these stars from the Fairborn 0.25mAutomatic Photometric Telescope (APT) that yielded a photometric periodin one case and rms deviations from apparently constant brightnesslevels for the remaining 11 stars. The Ca II data yielded rotationperiods for 10 out of 12 giant stars. We demonstrate that thephotometric variability and non-variability of these stars can bepredicted from their Rossby numbers calculated from our observedrotation periods and convective turnover times scaled up from the mainsequence. (SECTION: Stars)
|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.
|Evolved GK stars near the Sun. 2: The young disk population|
From a sample of nearly 2000 GK giants a group of young disk stars withwell determined space motions has been selected. The zero point of theluminosity calibrations, both from the ultraviolet flux (modifiedStroemgren system) and that in the region of 4200 to 4900 A (DDOsystem), show a discontinuity of about a half magnitude at the border ofthe young disk and old disk domains. The population separation is basedon the space velocity components, which are also an age discriminant,with the population interface near 2 x 109 yr, based onmodels with convective overshoot at the core. This age corresponds togiant masses near 1.7 solar mass, near the critical mass separating theyoung stars that do not burn helium in degenerate cores from older starsthat do. Ten percent of both populations show CN anomalies in that thederived value of P(Fe/H) from CN (Cm) and fromFe(M1) differ by more than 0.1 dex and the weak and strong CNstars occur equally in the old disk but the weak CN stars predominate inthe young disk. Peculiar stars, where flux distortions affect theluminosity calibrations, are of the CH+(Ba II) and CH-(weak G band)variety and represent less than 1% of the stars in both populations. Theyoung disk giants are restricted to ages greater than about109 yr, because younger stars are bright giants orsupergiants (luminosity class 2 or 1), and younger than about 2 x109 yr, because the old disk-young disk boundary occurs near1.7 solar mass. The distribution of heavy element abundances, P(Fe/H),for young disk giants is both more limited in range (+/- 0.4 dex) and isskewed toward higher abundances, compared with the nearly normaldistribution for old disk giants. The distribution of (U,V) velocityvectors gives (U,V,W) and their dispersions = (+17.6 +/- 18.4, -14.8 +/-8.4, -6.9 +/- 13.0) and (+3.6 +/- 38.4, -20.7 +/- 27.5, -6.7 +/-17.3)km/s for young and old disk giants, respectively.
|Velocity dispersions and mean abundances for Roman's G5-K1 spectroscopic groups|
The velocity dispersions and U-V distributions of Roman's (1950, 1952)four spectroscopic groups (weak CN, weak line, strong line, and 4150)are compared with those of groups based only on Fe/H ratio. It is shownthat the velocity-dispersion gradient for the Roman spectroscopic groupsis greater than for the comparison group for all three velocitycomponents and for the mean orbital eccentricity, with a clearly definedminimum for the strong-line stars and a sharp upturn for the 4150 stars.The results suggest that the Roman's assignment to distinctspectroscopic groups results in more homogeneous groups than the binningon the basis of metallicity.
|CA II H and K measurements made at Mount Wilson Observatory, 1966-1983|
Summaries are presented of the photoelectric measurements of stellar CaII H and K line intensity made at Mount Wilson Observatory during theyears 1966-1983. These results are derived from 65,263 individualobservations of 1296 stars. For each star, for each observing season,the maximum, minimum, mean, and variation of the instrumental H and Kindex 'S' are given, as well as a measurement of the accuracy ofobservation. A total of 3110 seasonal summaries are reported. Factorswhich affect the ability to detect stellar activity variations andaccurately measure their amplitudes, such as the accuracy of the H and Kmeasurements and scattered light contamination, are discussed. Relationsare given which facilitate intercomparison of 'S' values with residualintensities derived from ordinary spectrophotometry, and for convertingmeasurements to absolute fluxes.
|High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances|
A high-resolution spectroscopic survey of 671 G and K field giants isdescribed. Broad-band Johnson colors have been calibrated againstrecent, accurate effective temperature, T(eff), measurements for starsin the range 3900-6000 K. A table of polynomial coefficients for 10color-T(eff) relations is presented. Stellar atmosphere parameters,including T(eff), log g, Fe/H, and microturbulent velocity, are computedfor each star, using the high-resolution spectra and various publishedphotometric catalogs. For each star, elemental abundances for a varietyof species have been computed using a LTE spectrum synthesis program andthe adopted atmosphere parameters.
|IUE and Einstein survey of late-type giant and supergiant stars and the dividing line|
Results are presented on an IUE UV survey of 255 late-type G, K, and Mstars, complementing the Maggio et al. (1990) Einstein X-ray survey of380 late-type stars. The large data sample of X-ray and UV detectionsmake it possible to examine the activity relationship between the X-rayand the UV emissions. The results confirm previous finding of a trendinvolving a steeply-dropping upper envelope of the transition regionline fluxes, f(line)/f(V), as the dividing line is approached. Thissuggests that a sharp decrease in maximum activity accompanies theadvancing spectral type, with the dividing line corresponding to thissteep gradient region. The results confirm the rotation-activityconnection for stars in this region of the H-R diagram.
|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.
|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.
|A list of MK standard stars|
|The Perkins catalog of revised MK types for the cooler stars|
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
|Stellar integrated fluxes in the wavelength range 380 NM - 900 NM derived from Johnson 13-colour photometry|
Petford et al. (1988) have reported measured integrated fluxes for 216stars with a wide spread of spectral type and luminosity, and mentionedthat a cubic-spline integration over the relevant Johnson 13-colormagnitudes, converted to fluxes using Johnson's calibration, is inexcellent agreement with those measurements. In this paper a list of thefluxes derived in this way, corrected for a small dependence on B-V, isgiven for all the 1215 stars in Johnson's 1975 catalog with completeentries.
Submit a new link
Member of following groups:
Observation and Astrometry data
|Proper motion RA:||-8|
|Proper motion Dec:||-8.6|
Catalogs and designations: