내용
사진
사진 업로드
DSS Images Other Images
관련 글
Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters
Context: Radial velocities have proved to be an efficient method formembership determination if there are at least 2 or 3 red giants in acluster. They are necessary for galactic studies, but are still missingfor many open clusters. Aims: We present the final catalogues of along-term observing programme performed with the two coravelspectrovelocimeters for red giants in open clusters. The main aims wereto detect spectroscopic binaries and determine their orbital parameters,determine the membership, and compute mean velocities for the stars andopen clusters. Methods: We computed weighted mean radial velocities for1309 stars from 10 517 individual observations, including the systemicradial velocities from spectroscopic orbits and for cepheids. Results:The final results are contained in three catalogues collecting 10 517individual radial velocities, mean radial velocities for 1309 redgiants, and mean radial velocities for 166 open clusters among whichthere are 57 new determinations. We identified 891 members and 418non-members. We discovered a total of 288 spectroscopic binaries, amongwhich 57 are classified as non-members. In addition 27 stars were judgedto be variable in radial velocities and they are all red supergiants. Conclusions: The present material, combined with recent absolute propermotions, will permit various investigation of the galactic distributionand space motions of a large sample of open clusters. However, thedistance estimates still remain the weakest part of the necessary data.This paper is the last one in this series devoted to the study of redgiants in open clusters based on radial velocities obtained with thecoravel instruments.Based on observations collected at the Haute-Provence Observatory(France) and on observations collected with the Danish 1.54-m telescopesat the European Southern Observatory, La Silla, Chile. Full Tables [seefull textsee full textsee full textsee full textsee full text] to [seefull textsee full textsee full textsee full textsee full text] are onlyavailable and Tables [see full textsee full textsee full textsee fulltextsee full text] and [see full textsee full textsee full textsee fulltextsee full text] are also 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/485/303
| Na, Al, and O Abundances of Open Clusters NGC 7142, NGC 6939, and IC 4756
We present an analysis of echelle spectra of stars in three openclusters obtained with the Hydra multiobject spectrograph on the WIYN3.5 m telescope. Abundances of Fe, O, Si, Ca, Na, Al, and Ni have beendetermined via equivalent width analysis and spectrum synthesis. Meanabundances for each cluster are compared to those of previous studiesand of other clusters in the literature, with emphasis on exploring theenhancements of Na and Al seen in many open clusters. All three clustersshow enhanced values of [Na/Fe] and [Al/Fe], while the abundances of Fe,O, Si, and Ca are consistent with their ages and locations in theGalactic disk.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| delta Scuti-type pulsation in the eclipsing and spectroscopic binary HD 172189 in the cluster IC 4756.
The binary system nature of the HD 172189 as well as the presence of thepulsating delta Scuti-type component in the system have beendiscovered. The great interest of this object lies in that threeimportant characteristics coexist: membership of the cluster IC 47456,binary and pulsation. An orbital period of 5.702 d has been found. Afrequency analysis of all the uvby out-of-primary-eclipse measurementsreveals a dominant frequency of 19.5974 c/d as well as high values inthe range of 18-20 c/d. In addition, it is located in the FOV of COROTmission, being a good candidate for its observation from space.
| HD 172189: an eclipsing and spectroscopic binary with a δ Sct-type pulsating component in an open cluster
We present a study based on more than 2500 uvby-measurements collectedon HD 172189, a new eclipsing binary system with a δ Sct-typepulsating component that belongs to the open cluster IC 4756. The greatinterest of this object lies in that three important characteristicscoexist: cluster membership, binarity and pulsation. Its binarity andthe δ Sct-type pulsations of one component were detected in thecourse of several Strömgren photometric campaigns. The frequencyanalysis of all the uvby out-of-eclipse data reveals a clear frequencyof 19.5974 cd-1as well as the existence of other high valuesin the range 18-20 cd-1. We have also carried out a firstevaluation of the binary parameters and determined a value of 5.702 dfor the orbital period. An additional potential interest of HD 172189resides in its location in the field of view of the COROT mission and,therefore, this star is an excellent candidate for becoming a target forasteroseismology.
| 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
| Open clusters with Hipparcos. I. Mean astrometric parameters
New memberships, mean parallaxes and proper motions of all 9 openclusters closer than 300 pc (except the Hyades) and 9rich clusters between 300 and 500 pc have been computed using Hipparcosdata. Precisions, ranging from 0.2 to 0.5 mas for parallaxes and 0.1 to0.5 mas/yr for proper motions, are of great interest for calibratingphotometric parallaxes as well as for kinematical studies. Carefulinvestigations of possible biases have been performed and no evidence ofsignificant systematic errors on the mean cluster parallaxes has beenfound. The distances and proper motions of 32 more distant clusters,which may be used statistically, are also indicated. Based onobservations made with the ESA Hipparcos astrometry satellite
| 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
| Amendment of our method for deriving stellar membership of an open cluster
Our method for determining statistically the members of an open clusterby means of the proper motions (Missana et al.) is amended and itsvalidity is verified by applying it to the cluster IC 4756 with the datagiven by Herzog et al. (1975), adding nothing to their results. In thecomputation of the dispersion ellipses of the samples and of theChi2 for deriving the significance levels, the weights of theproper motions have been taken into account. The results obtained by thecriterion of the Chi2 and those obtained by Herzog et al. bythe criterion of the maximum likelihood of Sanders (1971) areconcordant.
| 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.
| Chromospheric Activity in Galactic Open Clusters
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993ApJ...417..157B&db_key=AST
| Red giants in open clusters. III - Binarity and stellar evolution in five intermediate-age clusters: NGC 2360, 2423, 5822, 6811, and IC 4756
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990A&A...237...61M&db_key=AST
| A four-color and Hbet study of the galactic cluster IC 4756.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978PASP...90..157S&db_key=AST
| Membership and photometry of the open cluster IC 4756
Probabilities of membership, based on relative proper motions, for 464stars in the field of IC 4756 are given. The cluster proper motiondispersion (m.e.) of 0.09 sec of arc yields 173 probable members.Photographic UBV magnitudes of 471 stars in the field are presented. Thecolor excess of IC 4756 is E(B-V) equal to 0.19 min; the apparentdistance modulus equals 8.5 min, corresponding to the true distance of400 pc. The membership probabilities of 6 blue stragglers and of thesupergiant HD 172365 (F9 Ib) are discussed.
| Untersuchung der offenen Sternhaufen IC 4665, NGC 6633, IC 4756
Not Available
|
새 글 등록
관련 링크
새 링크 등록
다음 그룹에 속해있음:
|
관측 및 측정 데이터
천체목록:
|
