Quantitative Stellar Spectral Classification. IV. Application to the Open Cluster IC 2391
In this work we perform the first test of a stellar spectralclassification method (Stock & Stock 1999) by applying it to earlytype stars. The sample of stars are the members of the open cluster IC2391 that have high-resolution spectra available in the UVES Project ofParanal Observatory. We show that, in general, absolute magnitudes M_Vand intrinsic colors (B-V)_0 can be recovered within the uncertaintiesstated in the original calibration (˜ 0.4 for the magnitudes and˜ 0.03 for the colors). This accuracy allows us to estimatedistances and to infer membership of individual stars to obtain anaverage distance to the cluster of 156+/-24 pc, which is in goodagreement with previously reported determinations. Finally, we identifyand discuss the real strengths and limitations of this method and wesuggest how it can be improved for future studies.
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WIYN open cluster study. XXVI. Improved kinematic membership and spectroscopy of IC 2391
Context: Young open clusters provide important clues to the interfacebetween the main sequence and pre-main-sequence phases of stellarevolution. The young and nearby open cluster IC 2391 is well-suited tostudies of these two evolutionary phases. Aims: We establish a bonafide set of cluster members and then analyze this set in terms of binaryfrequency, projected rotational velocities, [Fe/H], and lithiumabundance. In the wake of the Hipparcos distance controversy for thePleiades, we compare the main-sequence fitting distance modulus to theHipparcos mean parallax for IC 2391. Methods: We have obtained newproper motions for 6991 stars down to V ˜ 13-16 over a~9-deg2 area of the sky comprising IC 2391. The precision ofproper motions, σ_μ=1.7 mas yr-1, allowed us tocalculate reliable membership probabilities. We also obtained preciseradial velocity and v sin i measurements with Coravel and FEROS for 76probable cluster members. The cluster's mean radial velocity is+14.8±0.7 km s-1. The FEROS high-resolution spectrawere used to determine both the [Fe/H] abundance in the four mainsequence dwarfs of IC 2391 and the Li abundance in 47 stars. Inaddition, new BV CCD photometry was obtained for the majority ofprobable cluster members. Results: The proper-motion survey covers a 6times larger sky area than the prior targeted searches for clustermembers in IC 2391. A total of 66 stars are considered bona fide clustermembers down to a mass equivalent to 0.5 Mȯ. A quarterof them have been newly identified with many in the F2-K5 spectralrange, which is crucial for a main-sequence fit. We find a mean [Fe/H]value of +0.06±0.06, when a solar abundance of log ɛ(Fe)= 7.45 is adopted. The main sequence fitting yields a distance modulusthat is 0.19 mag larger than that derived from Hipparcos parallaxes;thus this offset nearly has the size of a similar offset found for thePleiades. The Li abundance pattern is similar to the earlier findingsand is typical for a 40 Myr old open cluster. Conclusions: .A varietyof new data on the probable members of IC 2391 improve essentially allobservational parameters of this young open cluster.
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Abundance analysis of 5 early-type stars in the young open cluster IC 2391
Aims.It is unclear whether chemically peculiar stars of the upper mainsequence represent a class completely distinct from normal A-type stars,or whether there exists a continuous transition from the normal to themost peculiar late F- to early B-type stars. A systematic abundanceanalysis of open cluster early-type stars would help to relate theobserved differences of the chemical abundances of the photospheres toother stellar characteristics, without being concerned by possibledifferent original chemical composition. Furthermore, if a continuoustransition region from the very peculiar to the so called normal A-Fstars exists, it should be possible to detect objects with mildpeculiarities. Methods: .As a first step of a larger project, anabundance analysis of 5 F-A type stars in the young cluster IC 2391 wasperformed using high resolution spectra obtained with the UVESinstrument of the ESO VLT. Results: .Our targets seem to follow ageneral abundance pattern: close to solar abundance of the lightelements and iron peak elements, heavy elements are slightlyoverabundant with respect to the sun, similar to what was found inprevious studies of normal field A-type stars of the galactic plane. Wedetected a weakly chemically peculiar star, HD 74044. Its elementpattern contains characteristics of CP1 as well as CP2 stars, enhancedabundances of iron peak elements and also higher abundances of Sc, Y, Baand Ce. We did not detect a magnetic field in this star (detection limitwas 2 kG). We also studied the star SHJM 2, proposed as a pre-mainsequence object in previous works. Using spectroscopy we found a highsurface gravity, which suggests that the star is very close to theZAMS.
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Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
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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
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The Evolution of Stellar Coronae: Initial Results from a ROSAT PSPC Observation of IC 2391
Not Available
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Liste des étoiles Ap et Am dans les amas ouverts (édition révisée)
Not Available
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The IC 2391 supercluster
Sixty-three field stars and the sparse cluster IC 2391 have beenidentified as members of the IC 2391 supercluster. The members have atleast 95 percent of their space motion, directed toward (A,D) = (5.82h,- 12.44d). Like members of the very similar Pleiades supercluster, theIC 2391 supercluster contains objects of two ages: t = 8 x 19 exp 7 and2.5 x 10 exp 8 yr. A prototype very active chromosphere star and theenigmatic giant variable TZ For are supercluster members together withtwo A-type stars suspected of possessing particulate disks. Anespecially interesting member is the system of Xi Cep (HR 8417) in whichthe two brightest components are greatly undermassive.
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Liste des étoiles Ap et Am dans les amas ouverts (Edition révisée)
Not Available
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Catalog of AP and AM stars in open clusters
The previous results of Raab (1922), Markarian (1951), and Collinder(1931) have been used to catalog Ap and Am stars that are in the fieldof open clusters. Tabular data are presented for the clusterdesignation, the HD or HDE number, the right ascension (1900), thedeclination (1900), and the magnitude. Also listed are the spectraltypes and, for certain stars, the probability of cluster membership.
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Radial velocities in the open cluster IC 2391
Radial velocities have been determined for 31 stars in the field of theopen cluster IC 2391, and the percentage of probable radial-velocityvariables is derived. The orbit of one previously known spectroscopicbinary is improved, and the existence of two double-line binaries isconfirmed. The membership to the cluster and the average cluster radialvelocity are discussed and the incidence of short-period binaries amongthe Main-Sequence members of IC 2391 is compared with the incidence forother clusters with similar average axial rotation of its members.
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Chemically peculiar stars in open clusters. I - The catalog
The largest existing compilation is presented of Ap and Am open clusterstars. The catalog contains information on 381 chemically peculiar (CP)stars of the upper main sequence in 79 open clusters. The catalog iscomposed of the following tables: (1) the main body, which lists CP (orsuspected CP) stars which are kinematical (or suspected kinematical)members of open clusters; (2) the list of CP (or suspected CP) starssometimes numbered among cluster members but which are actuallykinematical nonmembers; (3) the list of stars sometimes designated as'peculiar' but, in fact, probably not CP; (4) references for numberingsystems of cluster stars; (5) references for membership; and (6)references for spectral and/or peculiarity types.
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Photoelectric search for CP2-stars in open clusters. VIII - IC 2391 and NGC 2451
Delta-a photometry for 90 stars in the areas of the rather young openclusters IC 2391 and NGC 2451, covering the whole spectral domain ofCP2-stars, is presented. Seven stars show up as photometricallypeculiar, but membership is probable only for 4, 2 for each cluster. NGC2451 may have to be divided into a near and a far cluster. IC 2391 isunreddened and presents itself as ideal reference for the normality linein the Delta-a photometry. Crawford's (1978) calibration yields absolutemagnitudes for the peculiar stars which result in distance moduli veryclose to the mean cluster modulus. Again it is possible to confront thediversity of spectral classifications with the photometric peculiarityindex Delta-a.
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Axial rotational velocities in the open cluster IC 2391
Projected rotational velocities have been determined for the members ofthe open cluster IC 2391. The results are discussed in the context ofthe statistical relation between axial rotation and percentage ofbinaries found by Abt (1962) for open clusters and associations.
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Spectral morphology in the open cluster IC 2391
Thirty-one stars brighter than B = 10 in the field of the open clusterIC 2391 are classified on the basis of the mean and MK dispersion. Byusing only normal stars of the main sequence and the absolute visualmagnitudes taken from the calibration made by Garrison (1978), adistance modulus of 5.9 + or - 0.07 (p.e.) magnitudes has been obtainedwhich corresponds to a distance of about 150 pc. A new Am star has beendiscovered, and the presence of two more, discovered earlier, has beenconfirmed. The spectra of the Silicon star HD 74535 and of a Si-Cr-Srobject are characterized.
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Six clusters in Puppis-Vela
Intermediate band and H-beta observations of stars in the clusters NGC2451, Cr 140, Cr 135, Cr 173, IC 2391, and Cr 132 in Puppis-Vela arediscussed. Photometric and astrometric parameters for the stars areshown and discussed, along with light and color curves, color-luminosityarrays, histograms for reddening and luminosity, and stellardistributions. Cr 132 consists mainly of members of CMa OB2 plus a fewstars that may be an extension of Cr 140. The latter is an elongatedcluster of some 20 stars, 450 pc distant, 30 million years old, and with(U,V,W) = (+27,-6,-16) km/s. Cr 135 has only eight members, including aK2 Ib star, some 30 million years old, 310 pc distant, and (U,V,W) =(+13,-11,-12) km/s. For NGC 2451, extensive photometry reveals nocluster. Cr 173 is in the Vela sheet and may contain Gamma Vel and thecepheid AH Vel. IC 2391 is a very extended cluster including about twodozen stars brighter than the sun, some 30 million years old and 165 pcdistant, with (U,V,W) = (+20,-19,-3) km/s.
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Properties of AM stars in the Geneva photometric system
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....92..289H&db_key=AST
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Relative radial velocities from objective prism spectra in the region of nine southern open star clusters and a star field at Eta Carinae
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...41..245G&db_key=AST
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Polarization measurements of 313 nearby stars
The linear polarization of 313 low galactic latitude stars has beenmeasured. With few exceptions all program stars have a spectral typelater than B9 and are within 600 parsec of the sun. 181 stars aresituated at the southern sky and 132 at the northern sky.
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Rotational Velocities in IC 2391
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974PASP...86..940L&db_key=AST
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Multicolor photometry of metallic-line stars. III. A photometric catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974RMxAA...1..175M&db_key=AST
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The Bibliographical Star Index
Not Available
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NGC 2516 and the Pleiades Group
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...173...63E&db_key=AST
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K-Line Photometry of Stars in Population i Clusters
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...23..453H&db_key=AST
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Variation of Metal Abundance in Stars in Population I Clusters
Abstract image available at:http://adsabs.harvard.edu/abs/1971PASP...83..173H
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Spectroscopic Studies of Southern Galactic Clusters, I. IC 2391
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969PASP...81..629P&db_key=AST
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Photometric studies of southern galactic cluster. I. IC 2391.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969AJ.....74..899P&db_key=AST
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INHABITED SKY
