Contenidos
Imágenes
Subir su imagen
DSS Images Other Images
Artículos relacionados
Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Comparative abundance analysis of the hot main sequence stars and their progeny in open cluster M 25
Remarkable inconsistencies between elemental abundances in the mainsequence stars and their progeny F-G supergiants are discussed.Comparative abundance analysis of the hot main sequence stars, thecepheid U Sgr and two cool supergiants belonging to young open cluster M25 is performed. The detected disaccord in the abundances of carbon,oxygen and other elements between these stars having a common origin butoccupying at present different evolutionary stages may be due to thefact that the chemical anomalies observed in B stars are caused by themechanism of the radiative diffusion in the upper atmosphere layers. Thechemical composition of B stars determined spectroscopically may notreflect correctly their true chemical composition, nor the chemicalcomposition of the interstellar medium. On the other hand such abundanceanomalies are not expected for F-G supergiants which have suffered thelarge scale mixing in the red giant phase. The observed abundances forthese objects are much more reliable as a reference point in the studyof galactic chemical evolution. Three new Be stars are discovered in M25. Our study has doubled the number of Be stars known in this cluster.
| Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
| HIPPARCOS data for two open clusters containing cepheids
Using proper motion data from the Hipparcos satellite it is shown thatthe cepheids S Nor and U Sgr are members of the open clusters NGC 6087and M 25, respectively. The precision of the Hipparcos data is needed toconclusively carry out a membership test. Parallax data, also obtainedfrom Hipparcos, do not contradict the proper motion results.
| 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
| 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.
| Open cluster chemical composition. 1: Later type stars in eight clusters
Abundance analyses of 36 stars associated with eight open clusters (IC2581, NGC 3532, NGC 5822, NGC 6067, NGC 6087, IC 4725 (M25), IC 4756,and NGC 6882/6885) are presented. The stars are primarily evolved G andK giants and supergiants. Cepheids in NGC 6067, NGC 6087, and IC 4725are included as are non-cluster Cepheids near the clusters NGC 3532, NGC6067, and IC 4725. With the addition of a background K giant in IC 4725,the total number of stars is 40. Elemental abundances derived includeLi, C, N, O, the alpha-elements, the Fe peak, and limited data on theheavy elements. The Na abundances of the sample show a gravitydependence in the sense of an increase in the abundance as the gravitydecreases. The CNO abundances indicate that these objects are processed(on the whole), and that they show the O deficiency previously noted inintermediate mass stars by Luck & Lambert (1981, 1985). There arefour stars in the sample which appear to be unprocessed: two giants andtwo supergiants. There are also two super-Li stars in the sample, one ofwhich is most likely a weak G-band star. It is suggested that thesuper-Li F supergiants could be evolved blue stragglers. The moststriking result of the study is the finding that the (O/Na) ratiocorrelates strongly with the gravity and the stellar mass, thus implyingthat there is a nonstandard additional mixing process affecting thesurface abundances of these stars. A promising candidate for the mixingprocess is the turbulent diffusive mixing process proposed byDenissenkov (1993) which brings Na to the surface and which could alsolead to a modification of the oxygen content.
| Photometry of F-K type bright giants and supergiants. 3: The luminosity, reddening, and heavy element abundance of GK stars
The reddening, luminosity, and heavy element abundance of 250 brightgiants and supergiants of type GK are discussed on the basis of 4 color,DDO, RI, and Geneva photometry Bright giants of type GK with age greaterthan 5 x 108 yr, and of type G0/3 with age greater than 2 x108 yr, are very scarce in the solar neighborhood. The medianspace motion vectors of the bright giants and supergiants with welldetermined space motions are (U, V, W) = (+10.6, -13.2, -7.7) +/- (12.3,8.8, 8.8) km/s. The M1 index for 4 color photometry, whencorrected for luminosity (gravity) effects, is sensitive to heavyelement abundance of the GK stars but may not be reliable for those oftype G0/3. The available spectroscopic determinations of (Fe/H) givemixed results with the two largest samples being internally consistentbut with a large zero-point difference. There is a similar zero-pointshift in the peak frequency of the photometrically determined values ofP(Fe/H) for the F type and for the GK type stars. There is littleevidence for an appreciable galactic, radial gradient in the P(Fe/H)values. A previously noted correlation of the heavy element abundanceindex, delta M1, with the amplitude defect in the B lightcurves of Cepheids, FB, and interpretation of the(PLFB) relation as a (PL(Fe/H)) relation needs furtherinvestigation in light of the apparent sensitivity of M1 toFe/H for the F stars (the domain of the Cepheids with P less than 10 d)and lack of this sensitivity for the G0/3 star (domain of the Cepheidswith P greater than 10 d).
| 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.
| Groups of stars with common motion in the Galaxy - Groups of red supergiants of the luminosity classes I and II
Not Available
| Colour excesses and absolute magnitudes for non-Cepheid F-G supergiants from uvbybeta photometry
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990A&A...239..205A&db_key=AST
| 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.
| Membership of Cepheids and red giants in 8 open clusters - NGC 129, 6067, 6087, 6649, 6664, IC 4725, LY 6, RU 79
The membership of eight cluster Cepheids,DL Cas,EV Sct, V367 Sct, S Nor,TW Nor,V340 Nor, U Sgr and CS Vel, has been examined by comparing theirsystemic radial velocity with that observed for the red giants in thesame clusters. The membership is very probable in seven cases, theonly-exception being CS Vel. Additional observations of main sequencestars are necessary to confirm some of the conclusions. Onespectroscopic binary was discovered among the Cepheids (DL Cas) and atleast four were among the red giants. Orbits have been determined fortwo red giants, one in NGC 129 and one in IC 4725. The position withinthe instability strip of the nonvariable F5Ib star in NGC 129 is due toits probable composite (gK + dB) character. The ratio of the number ofCepheids to the number of red giants is less than 1, in good agreementwith the prediction of evolutionary models with core overshooting. Thisstudy is based on 382 observations of 45 stars, obtained with the radialvelocity scanner CORAVEL.
| Spectral types and luminosities of supergiants in open clusters
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985PASP...97..297K&db_key=AST
| 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.
| Four-color and H-beta photometry of the galactic cluster M25
Four-color and H-beta photometry has been done for 39 stars in thegalactic cluster M25. The data are used to remove nonmember stars fromthe sample and to determine which stars are cluster members. A meandistance modulus of 8.76 and color excess of E(b-y) = 0.341 is found.
| DDO Observations of Southern Stars
Not Available
| Abundances of chemical elements in the atmospheres of K giants
The atmospheres of the giant stars of the spectral class KO IIIbelonging to the Hyades cluster, NGC 752, M 25, and UMa, areinvestigated with emphasis placed on differences in the abundances ofchemical elements. A modified method of differential curves of growthfor determining the actual abundances of chemical elements is presented.The characteristic abundances of stars belonging to different openclusters are found to be the same within the limits of the measurementerrors, and close to the abundances in the solar atmosphere. An excessof heavy elements of the iron group in the atmospheres of the stars N213 and HD 170820 is examined. Values of the degree of ionization areestimated using model atmospheres and effective depths of formation ofatomic absorption lines.
| The Abundances in Atmospheres the Cold Stars of Different Ages
Not Available
| Revised MK spectral types for G, K, and M stars
A catalog of spectral types of 552 G, K, and M stars is presented, whichis classified on the revised MK system. Stellar representatives of thehalo, disk, and arm populations in all parts of the sky are included.Photoelectric V magnitudes are given, as are intensity estimates of anyfeatures which make the spectrum appear peculiar as compared to thespectrum of a similar normal star. Abundance indices are also providedin the following lines or bands: CN, barium, Fe, calcium, and CH.
| A photoelectric measurement of magnesium for late-type stars
A photoelectric index of MgH + Mg b for late-type stars has been createdby the addition of one filter bandpass to the DDO system. Measurementsshow that this index has good sensitivity to surface gravity for Kstars, and suggest that it can differentiate metal-poor halo giants fromdisk stars. From this index, involving measurement through two filtersalone, it appears that membership can be determined for stars on thegiant branch of globular clusters. It is possible that the index couldbe used, after calibration with cluster giants, to determine ages ofgiant stars in the field.
| Abundance of chemical elements in atmospheres of cool stars.
Not Available
| UBV observations of the open cluster M25
The photoelectric calibration in the moderately young open cluster M25,which contains the Cepheid U Sgr, is extended on the basis of UBVobservations of 12 additional photoelectric standards with V magnitudesranging from 14.8 to 16.3. A mean B-V color excess of 0.51 + or - 0.1(m.e.) is obtained for 42 probable main-sequence stars within 5.0 arcminof the adopted cluster center. It is shown that a distance modulus of10.7 and a U-B color excess of 0.37 give a reasonable fit toSchmidt-Kaler's (1965) age-zero relation between absolute visualmagnitude and U-B, with the corresponding true distance modulus beingaround 9.0 for R = 3.3.
| Five-channel photometry of cepheids and supergiants in the southern Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...24..413P&db_key=AST
| Sodium in late-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&A.....7..408C&db_key=AST
| Abundances in K-Giant Stars. II. a Survey of Field Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968ApJS...16....1H&db_key=AST
| Equivalent Width of Hα in Late-Type Stars
Not Available
| A New Variable in M 25
Not Available
| Metal-to-H ratios in the Galaxy as indicated by narrow-band photometry of Cepheids.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966AJ.....71..615W&db_key=AST
|
Enviar un nuevo artículo
Enlaces relacionados
- - No se han encontrado enlaces -
En viar un nuevo enlace
Miembro de los siguientes grupos:
|
Datos observacionales y astrométricos
| Constelación: | Sagitario |
| Ascensión Recta: | 18h32m13.11s |
| Declinación: | -19°07'26.3" |
| Magnitud Aparente: | 7.358 |
| Distancia: | 427.35 parsecs |
| Movimiento Propio en Ascensión Recta: | -3.8 |
| Movimiento Propio en Declinación: | -6.3 |
| B-T magnitude: | 9.438 |
| V-T magnitude: | 7.53 |
Catálogos y designaciones:
|
INHABITED SKY
