Contents
Images
Upload your image
DSS Images Other Images
Related articles
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.
| 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
| J - K DENIS photometry of a VLTI-selected sample of bright southern stars
We present a photometric survey of bright southern stars carried outusing the DENIS instrument equipped with attenuating filters. Theobservations were carried out not using the survey mode of DENIS, butwith individual target pointings. This project was stimulated by theneed to obtain near-infrared photometry of stars to be used in earlycommissioning observations of the ESO Very Large TelescopeInterferometer, and in particular to establish a network of brightcalibrator sources.We stress that near-infrared photometry is peculiarly lacking for manybright stars. These stars are saturated in 2MASS as well as in regularDENIS observations. The only other observations available for brightinfrared stars are those of the Two Micron Sky Survey dating from overthirty years ago. These were restricted to declinations above≈-30°, and thus cover only about half of the sky accessible fromthe VLTI site.We note that the final 2MASS data release includes photometry of brightstars, obtained by means of point-spread function fitting. However, thismethod only achieves about 30% accuracy, which is not sufficient formost applications.In this work, we present photometry for over 600 stars, each with atleast one and up to eight measurements, in the J and K filters. Typicalaccuracy is at the level of 0\fm05 and 0\fm04 in the J and K_s bands,respectively.Based on observations collected at the European Southern Observatory, LaSilla.Tables 1 and 2 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/413/1037
| Metal Abundance of Red Clump Stars in Baade's Window
Thirteen red clump stars from Baade's window were observed with highresolution in the red part of the optical spectrum with the UVES echellespectrograph at the Mount Paranal ESO Observatory. The model atmosphereabundance analysis placed their [Fe/H] values in a range from 0.0 to-1.52 dex. Present results, based on direct measurements of ironabundance, confirm former suggestions that the I-band brightness of thered clump giants only weakly depends on [Fe/H]. The determined values of[Fe/H] may contain a slight systematic error connected with still nowunexplained difference in colors between stars in the Galactic bulge andin the solar vicinity.
| CHARM: A Catalog of High Angular Resolution Measurements
The Catalog of High Angular Resolution Measurements (CHARM) includesmost of the measurements obtained by the techniques of lunaroccultations and long-baseline interferometry at visual and infraredwavelengths, which have appeared in the literature or have otherwisebeen made public until mid-2001. A total of 2432 measurements of 1625sources are included, along with extensive auxiliary information. Inparticular, visual and infrared photometry is included for almost allthe sources. This has been partly extracted from currently availablecatalogs, and partly obtained specifically for CHARM. The main aim is toprovide a compilation of sources which could be used as calibrators orfor science verification purposes by the new generation of largeground-based facilities such as the ESO Very Large Interferometer andthe Keck Interferometer. The Catalog is available in electronic form atthe 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/386/492, and from theauthors on CD-Rom.
| New binary stars discovered by lunar occultations. II.
This paper is the second in a series, following the one by Richichi etal. (1994a, hereafter Paper I), reporting discoveries of new binarystars in the course of routine lunar occultation programs at the TIRGOand Calar Alto observatories, or re-observations of known or suspectedbinaries where only incomplete information was available. We report on atotal of 15 sources. In the following eight cases, we detected acompanion for the first time: SAO 93127, SAO 93195, SAO 95677, SAO96110, SAO 97246, SAO 97258, SAO 183637, AG +15 845. For two stars, SAO76131 and SAO 184822, we confirm previous reports of binarity, with ourIR measurements complementing existing visual information. In the caseof the five stars SAO 93484, SAO 96746, SAO 128467, SAO 157923 (αVir), and SAO 162413, a companion had also been previously observed, butwe could not detect it in our observation. Our negative detection inmost of these cases provides a constraint on the characteristics of thecompanion. The projected separations in our positive results range from0.79" to 0.006", and the range of brightness ratios from =~1:1 to 1:150.The faintest companion has K=~11. The performance of the lunaroccultations technique offers a valid complement to other more modernmethods such as speckle interferometry and long baseline interferometry,and in fact many of the stars in our list could not be resolved byprevious attempts using these latter techniques. In addition to standardobservations by fast photometers, in this paper we include and describethe routine use of an IR array detector to record lunar occultations,which offered significant improvement in sensitivity.
| 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.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
| A photometric survey of the bright southern Be stars
Repeated UBV photometric measurements were made of the 86 bright Bestars south of declination -20 deg, and a network of comparison starswas set up. From a statistical study of the differential photometry itwas found that short- or intermediate-term variability seems to beoccurring in about half of the Be stars, and to be more evident in thestars of earlier spectral type. It was also possible to identify 11individual short- or intermediate-term variables. Four of these (all ofearly B spectral type) appear to exhibit significant variability on atime-scale of a day or less. More intensive observations of one of thesestars, 28 Omega CMA, indicate short-term variations consistent with thepublished spectroscopic period of 1.37 day.
| 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.
| 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.
| The barium and R type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.159..403E&db_key=AST
| Luminosities, Temperatures, and Kinematics of K-Type Dwarfs
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...22..389E&db_key=AST
| Narrow-Band and Broad-Band Photometry of Red Stars. III. Southern Giants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...161..199E&db_key=AST
| Stellar Groups in the Old Disk Population
Not Available
| Photoelectric determination of the colors of 286 stars south of declination -15 degrees.
Not Available
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Ζυγός |
| Right ascension: | 15h37m48.10s |
| Declination: | -23°08'30.0" |
| Apparent magnitude: | 5.78 |
| Distance: | 83.542 parsecs |
| Proper motion RA: | -30.5 |
| Proper motion Dec: | -78.5 |
| B-T magnitude: | 7.147 |
| V-T magnitude: | 5.908 |
Catalogs and designations:
|
