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Elemental abundances in the atmosphere of clump giants
Aims.The aim of this paper is to provide the fundamental parameters andabundances for a large sample of local clump giants with a highaccuracy. This study is a part of a big project, in which the verticaldistribution of the stars in the Galactic disc and the chemical anddynamical evolution of the Galaxy are being investigated. Methods:.The selection of clump stars for the sample group was made applying acolour-absolute magnitude window to nearby Hipparcos stars. Theeffective temperatures were estimated by the line depth ratio method.The surface gravities (log {g}) were determined by two methods (thefirst one was the method based on the ionization balance of iron and thesecond one was the method based on fitting of the wings of the Ca I6162.17 Å line). The abundances of carbon and nitrogen wereobtained from the molecular synthetic spectrum, and the Mg and Naabundances were derived using the non-LTE approximation. The "classical"models of stellar evolution without atomic diffusion androtation-induced mixing were employed. Results: .The atmosphericparameters ({T_eff}, log {g}, [Fe/H], {Vt}) and Li, C, N, O,Na, Mg, Si, Ca, and Ni abundances in 177 clump giants of the Galacticdisc were determined. The underabundance of carbon, overabundance ofnitrogen, and "normal" abundance of oxygen were detected. A small sodiumoverabundance was found. A possibility of a selection of the clumpgiants based on their chemical composition and the evolutionary trackswas explored. Conclusions: .The theoretical predictions based onthe classical stellar evolution models are in good agreement with theobserved surface variations of the carbon and nitrogen just after thefirst dredge-up episode. The giants show the same behaviour of thedependencies of O, Mg, Ca, and Si (α-elements) and Ni (iron-peakelement) abundances vs. [Fe/H] as dwarfs do. This allows us to use suchabundance ratios to study the chemical and dynamical evolution of theGalaxy.
| Stellar Parameters and Photospheric Abundances of Late-G Giants: Properties of the Targets of the Okayama Planet Search Program
Towards clarifying the properties of late-G giants, for which we arecurrently conducting a planet-search project at Okayama AstrophysicalObservatory, an extensive spectroscopic study has been performed for ourfirst target sample of fifty-seven G6-G9 III stars, in order toestablish the atmospheric parameters (Teff, log g,vt, and [Fe/H]), the stellar mass along with the evolutionarystatus, and the photospheric abundances of various elements. It wasconfirmed that the conventional spectroscopic method of parameterdetermination using Fe I / II lines with the assumption of LTE workssuccessfully for these evolved stars. We determined the abundances(relative to the Sun) of 19 elements, and examined how their [X/Fe]ratios behave themselves with the run of [Fe/H]. While the trends appearto be similar to those exhibited by disk dwarfs for a number ofelements, some elements (C, O, Na) showed appreciable anomalies, whichmay be interpreted as being due to a dredge-up of nuclear-processedmaterial. Since the [Fe/H] values of these stars tend to be somewhatbiased towards a subsolar regime, some mechanism of slightly reducingthe metallicity might be suspected.
| Radial-Velocity Variability of G-Type Giants: First Three Years of the Okayama Planet Search Program
We report on the radial-velocity variability of G-type giants based onthe results of precise Doppler measurements of 57 stars that wereobserved for the first 3 years of the Okayama Planet Search Program.This program aims to search for planets around intermediate-mass starsin their evolved stages as late-G giants. We found that most of thetargets with B ‑ V < 1.0 have radial-velocity scatters ofσ 10 m s-1, with the most stable reaching levels of6‑8 m s-1, while those with B ‑ V > 1.0 typically showσ 20 m s-1. In total, about 60% of the targets are stable inradial velocity to a level of σ < 15 m s-1 over 1-3 years, andabout 90% have σ < 30 m s-1. We found that 4 stars (HD 30557,HD 34559, HD 68077, and HD 85444) show significant long-termradial-velocity trends, suggesting that they are probably orbited byunseen stellar or substellar companions. Three stars (HD 79181, HD104985, and HD 141680) show periodic radial-velocity variations. HD104985 is the first planet-harboring star discovered from our survey.The properties of the variations in these 3 stars have been, and willbe, extensively discussed in separate papers. Relatively large, but notapparently periodic, radial-velocity variations of σ > 30 m s-1are found in 4 stars (HD 41597, HD 134190, HD 161178, and HD 176598).For most of the stars without showing any significant periodicity, wecan exclude companions with K > 50 m s-1, or m2sini > 1.8 MJ (a/AU)1/2(M*/Mȯ)1/2 for orbital radii a ≲ 1‑2 AU.
| 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.
| 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
| Rotation and lithium in single giant stars
In the present work, we study the link between rotation and lithiumabundance in giant stars of luminosity class III, on the basis of alarge sample of 309 single stars of spectral type F, G and K. We havefound a trend for a link between the discontinuity in rotation at thespectral type G0III and the behavior of lithium abundances around thesame spectral type. The present work also shows that giant starspresenting the highest lithium contents, typically stars earlier thanG0III, are those with the highest rotation rates, pointing for adependence of lithium content on rotation, as observed for otherluminosity classes. Giant stars later than G0III present, as a rule, thelowest rotation rates and lithium contents. A large spread of about fivemagnitudes in lithium abundance is observed for the slow rotators.Finally, single giant stars with masses 1.5 < M/Msun<=2.5 show a clearest trend for a correlation between rotational velocityand lithium abundance. Based on observations collected at theObservatoire de Haute -- Provence (France) and at the European SouthernObservatory, La Silla (Chile). Table 2 is only available electronicallywith the On-Line publication athttp://link.springer.de/link/service/00230/
| A catalog of rotational and radial velocities for evolved stars
Rotational and radial velocities have been measured for about 2000evolved stars of luminosity classes IV, III, II and Ib covering thespectral region F, G and K. The survey was carried out with the CORAVELspectrometer. The precision for the radial velocities is better than0.30 km s-1, whereas for the rotational velocity measurementsthe uncertainties are typically 1.0 km s-1 for subgiants andgiants and 2.0 km s-1 for class II giants and Ib supergiants.These data will add constraints to studies of the rotational behaviourof evolved stars as well as solid informations concerning the presenceof external rotational brakes, tidal interactions in evolved binarysystems and on the link between rotation, chemical abundance and stellaractivity. In this paper we present the rotational velocity v sin i andthe mean radial velocity for the stars of luminosity classes IV, III andII. Based on observations collected at the Haute--Provence Observatory,Saint--Michel, France and at the European Southern Observatory, LaSilla, Chile. Table \ref{tab5} also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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 (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The photoelectric astrolabe catalogue of Yunnan Observatory (YPAC).
The positions of 53 FK5, 70 FK5 Extension and 486 GC stars are given forthe equator and equinox J2000.0 and for the mean observation epoch ofeach star. They are determined with the photoelectric astrolabe ofYunnan Observatory. The internal mean errors in right ascension anddeclination are +/- 0.046" and +/- 0.059", respectively. The meanobservation epoch is 1989.51.
| 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.
| Speckle imaging with the MAMA detector: Preliminary results
We report on the first successful speckle imaging studies using theStanford University speckle interferometry system, an instrument thatuses a multianode microchannel array (MAMA) detector as the imagingdevice. The method of producing high-resolution images is based on theanalysis of so-called 'near-axis' bispectral subplanes and follows thework of Lohmann et al. (1983). In order to improve the signal-to-noiseratio in the bispectrum, the frame-oversampling technique of Nakajima etal. (1989) is also employed. We present speckle imaging results ofbinary stars and other objects from V magnitude 5.5 to 11, and thequality of these images is studied. While the Stanford system is capableof good speckle imaging results, it is limited by the overall quantumefficiency of the current MAMA detector (which is due to the response ofthe photocathode at visible wavelengths and other detector properties)and by channel saturation of the microchannel plate. Both affect thesignal-to-noise ratio of the power spectrum and bispectrum.
| APT Observations of Small-Amplitude Red Variables
Not Available
| A critical appraisal of published values of (Fe/H) for K II-IV stars
'Primary' (Fe/H) averages are presented for 373 evolved K stars ofluminosity classes II-IV and (Fe/H) values beween -0.9 and +0.21 dex.The data define a 'consensus' zero point with a precision of + or -0.018 dex and have rms errors per datum which are typically 0.08-0.16dex. The primary data base makes recalibration possible for the large(Fe/H) catalogs of Hansen and Kjaergaard (1971) and Brown et al. (1989).A set of (Fe/H) standard stars and a new DDO calibration are given whichhave rms of 0.07 dex or less for the standard star data. For normal Kgiants, CN-based values of (Fe/H) turn out to be more precise than manyhigh-dispersion results. Some zero-point errors in the latter are alsofound and new examples of continuum-placement problems appear. Thushigh-dispersion results are not invariably superior to photometricmetallicities. A review of high-dispersion and related work onsupermetallicity in K III-IV star is also given.
| MK classification and photometry of stars used for time and latitude observations at Mizusawa and Washington
MK spectral classifications are given for 591 stars which are used fortime and latitude observations at Mizusawa and Washington. Theclassifications in the MK system were made by slit spectrograms ofdispersion 73 A/mm at H-gamma which were taken with the 91 cm reflectorat the Okayama Astrophysical Observatory. Photometric observations in UBV were made with the 1-meter reflector at the Flagstaff Station of U.S.Naval Observatory. The spectrum of HD 139216 was found to show a strongabsorption line of H-beta. The following new Am stars were found:HD9550, 25271, 32784, 57245, 71494, and 219109. The following new Apstars were found: HD6116, 143806, 166894, 185171, and 209260. The threestars, HD80492, 116204, and 211376, were found to show the emission inCaII H and K lines.
| A search for lithium-rich giant stars
Lithium abundances or upper limits have been determined for 644 brightG-K giant stars selected from the DDO photometric catalog. Two of thesegiants possess surface lithium abundances approaching the 'cosmic' valueof the interstellar medium and young main-sequence stars, and eight moregiants have Li contents far in excess of standard predictions. At leastsome of these Li-rich giants are shown to be evolved to the stage ofhaving convectively mixed envelopes, either from the direct evidence oflow surface carbon isotope ratios, or from the indirect evidence oftheir H-R diagram positions. Suggestions are given for the uniqueconditions that might have allowed these stars to produce or accrete newlithium for their surface layers, or simply to preserve from destructiontheir initial lithium contents. The lithium abundance of the remainingstars demonstrates that giants only very rarely meet the expectations ofstandard first dredge-up theories; the average extra Li destructionrequired is about 1.5 dex. The evolutionary states of these giants andtheir average masses are discussed briefly, and the Li distribution ofthe giants is compared to predictions of Galactic chemical evolution.
| Radial velocity measurements. II - Ground-based observations of the program stars for the HIPPARCOS satellite
New radial velocities for 446 stars of magnitude 9.0 or brighter in 1616-sq-deg fields of the Northern Hemisphere are determined by automaticPDS measurement of 80-A/mm-dispersion spectra obtained at theObservatoire de Haute Provence using a 17-cm-diameter objective prism.The fields were selected to provide data for the input catalog of theESA Hipparcos astrometric satellite. The measurement techniques andprecision are discussed, and the results are presented in extensivetables and graphs.
| Photoelectric UBV photometry for 317 PZT and VZT stars
UBV data were taken of 317 stars to fill gaps in photoelectric recordsneeded for establishing a terrestrial reference frame for earthorientation purposes. The study supplied the magnitudes and colors andaided in identifying nearby stars without trigonometric parallaxes. Thesurvey averaged over three observations of each object. A complete tableof the V, B-V, U-B and number of observations of each object isprovided.
| Narrow-band photometry of G and K stars near the North Galactic Pole
Photoelectric narrow-band photometry obtained for 292 late-type starsbrighter than 10 m in the North Galactic Pole area is discussed. The g,n, k, m, f-system of Dickow et al. (1970) is used. The stars were chosenfrom two lists: (1) all stars of spectral type G5 or later in the HenryDraper Catalog (Cannon and Pickering, 1918-1924) within 15 deg of theNorth Galactic Pole, together with a few BD stars; and (2) all starsclassified as K or M giants and in Upgren's 25-31 deg zones (Upgren,1962). For most of the stars, estimates of the following quantities arederived: V-magnitude, R-I color, metal abundance, MV, and theduplicity parameter res(k).
| MK spectral types for some F and G stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979PASP...91...83C&db_key=AST
| An improved spectroscopic orbit for the white dwarf eclipsing binary BD +16 deg 516
Original spectrograms plus newly acquired ones have been remeasured andanalyzed along with numerous standard stars to provide a more definitiveorbit solution and center-of-mass radial velocity for this importantbinary. Evidence from the Ca II emission lines suggests that achromospheric 'event' may have been observed which is related to massexchange.
| Cyanogen Strengths, Luminosities, and Kinematics of K Giant Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJS...29..161J&db_key=AST
| Erratum : MK classification for F- and G-type stars. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..507H&db_key=AST
| MK classifications for F-and G-type stars. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..165H&db_key=AST
| Narrow-band photometry of late-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..199H&db_key=AST
| Polarimetric Observations of Nearby Stars in the Directions of the Galactic Poles and the Galactic Plane
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968ApJ...151..907A&db_key=AST
| MK Spectral Types for 185 Bright Stars
Not Available
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Osservazione e dati astrometrici
| Costellazione: | Boote |
| Ascensione retta: | 13h41m02.30s |
| Declinazione: | +22°29'45.0" |
| Magnitudine apparente: | 5.62 |
| Distanza: | 98.717 parsec |
| Moto proprio RA: | -15.7 |
| Moto proprio Dec: | -25 |
| B-T magnitude: | 6.921 |
| V-T magnitude: | 5.736 |
Cataloghi e designazioni:
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INHABITED SKY
