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מאמרים קשורים
Galactic model parameters for field giants separated from field dwarfs by their 2MASS and V apparent magnitudes
We present a method which separates field dwarfs and field giants bytheir 2MASS and V apparent magnitudes. This method is based onspectroscopically selected standards and is hence reliable. We appliedit to stars in two fields, SA 54 and SA 82, and we estimated a full setof Galactic model parameters for giants including their total localspace density. Our results are in agreement with the ones given in therecent literature.
| 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/.
| 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
| 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
| Sodium in weak G-band giants
Sodium abundances have been determined for eight weak G-band giantswhose atmospheres are greatly enriched with products of the CN-cyclingH-burning reactions. Systematic errors are minimized by comparing theweak G-band giants to a sample of similar but normal giants. If,further, Ca is selected as a reference element, model atmosphere-relatederrors should largely be removed. For the weak-G-band stars (Na/Ca) =0.16 +/- 0.01, which is just possibly greater than the result (Na/Ca) =0.10 /- 0.03 from the normal giants. This result demonstrates that theatmospheres of the weak G-band giants are not seriously contaminatedwith products of ON cycling.
| Lithium in late-type giants. III - The weak G band giants
Li abundances are presented for nine different stars to demonstrate thatthe abundances are consistent with the cosmic value. The observationswere made with the coude telescope and echelle spectrometer on La Silla,covering the Li I 6707 A resonance doublet and the 800 A 2-0 band. Thesurvey included the HD stars 18636, 31274, 36552, 40402, 78146 and 82595and the HR stars 1299 and 4154, all Southern Hemisphere weak FraunhoferG band objects. Both Li-6 and Li-7 were detected in HR 1299. It issuggested that the Li detected in all the stars convected outwardquickly and survived, while C diffused inward and was converted to C-13and N-14. The Li abundances can be observed in both main sequence andred giant stars.
| The lithium in weak G-band stars
Available data on Li abundance and CH band weakness in weak G-band starsindicates the existence of a linear relationship between Li and carbonabundance. Weak G-band stars with a high Li abundance are least depletedin C, and weak G-band stars with a relatively low Li abundance have avery low abundance of C. Li production seems to be a necessity after thestar leaves the main sequence and reaches the giant branch, probably byspallation reactions on the surface. Then mixing due to meridionalcirculation on the giant branch might bring out the CN-processedmaterial to the surface, at the same time destroying the surface Li.Thus, both C and Li abundances are depleted together.
| HD 91805 and the nature of the Bidelman-MacConnell weak-G-band stars
Spectroscopic and photometric observations of the weak-G-band star HD91805 are examined together with intermediate-band photometry of severalBidelman-MacConnell objects. Curve-of-growth and spectrum-synthesisanalyses of HD 91805 are performed to obtain insight into the productsof mixing; the results are found to be very similar to those reported bySneden and Peterson (1977) for HR 6766. Evidence based on theintermediate-band photometry is presented that the majority of theBidelman-MacConnell weak-G-band stars are burning helium in their coressubsequent to the helium core flash. Possible causes of the weak-G-bandanomaly are considered, and it is concluded that carbon depletion due tomeridional circulation requires the least radical departure from nowwell-understood astrophysical processes.
| The lithium abundance in weak-G band stars
Lithium abundances are derived for ten weak-G band giants. The stars arefound to have at least normal lithium abundances, and may have enhancedlithium relative to normal giants of similar temperature. Also, broadlines found in the G5 giant HR 1023 can be interpreted as rotation witha variable radial velocity of amplitude 17 + or - 5 km/sec. Possibleinterpretations of these results are discussed.
| The strength of the 2.3 MU CO band in weak-G-band stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..660H&db_key=AST
| Some observations of weak-G band stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..222D&db_key=AST
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משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | נחש מים |
| התרוממות ימנית: | 10h57m23.99s |
| סירוב: | -29°16'50.7" |
| גודל גלוי: | 8.485 |
| מרחק: | 423.729 פארסק |
| תנועה נכונה: | -14.4 |
| תנועה נכונה: | 16.7 |
| B-T magnitude: | 9.609 |
| V-T magnitude: | 8.578 |
קטלוגים וכינוים:
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