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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
| Search for X-ray flares in the Pleiades using SoHO LASCO C3 images. Not Available
| Search for gamma Doradus variable stars in the Pleiades cluster Photometric observations in the uvbybeta system of A-F type stars in thePleiades cluster have been performed in order to detect pulsatingvariable stars of gamma Doradus type in the lower part of the Cepheidinstability strip. In order to obtain more information about thebehaviour of the studied objects and to be able to distinguish betweenlong period variable and non-variable stars, two statistical methodshave been developed. Several of these stars show some type ofvariability but only two of the observed objects, H1284 and S29, can besafely classified as gamma Dor stars. Furthermore, these observationshave provided us with Strömgren and Hβ photometry,non-existing up to now for some of them, which permitted us to perform aphotometric study of the Pleiades cluster.
| The Lithium-Rotation Correlation in the Pleiades Revisited The dispersion in lithium abundance at fixed effective temperature inyoung cool stars like the Pleiades has proved a difficult challenge forstellar evolution theory. We propose that Li abundances relative to amean temperature trend, rather than the absolute abundances, should beused to analyze the spread in abundance. We present evidence that thedispersion in Li equivalent widths at fixed color in cool singlePleiades stars is at least partially caused by stellar atmosphereeffects (most likely departures from ionization predictions of modelphotospheres) rather than being completely explained by genuineabundance differences. We find that effective temperature estimates fromdifferent colors yield systematically different values for active stars.There is also a strong correlation between stellar activity and Liexcess, but not a one-to-one mapping between unprojected stellarrotation (from photometric periods) and Li excess. Thus, it is unlikelythat rotation is the main cause for the dispersion in the Li abundances.Finally, there is a significant correlation between detrended Li excessand potassium excess but not calcium-perhaps supporting incompleteradiative transfer calculations (and overionization effects inparticular) as an important source of the Li scatter. Other mechanisms,such as very small metallicity variations and magnetic fields, whichinfluence pre-main-sequence Li burning may also play a role. Finally, wefind no statistical evidence for a decrease in dispersion in the coolestPleiades stars, contrary to some previous work.
| Statistics of binaries in the Pleiades cluster We present a statistical analysis of binaries in galactic clusters,based on photometric properties. Synthetic clusters are used to solvethe deconvolution problem. If the colour-magnitude relation for singlestars is given and if triple stars are treated as binaries, thedistribution of systems in a colour-magnitude diagram (CMD) can be usedto determine cluster properties. They include the maximum number ofsingle stars N1max which is compatible with the distributionof systems, a standard deviation sigma (describing the scatter of starson the main sequence), a critical mass ratio q_c, and the mass ratiodistribution in the case of N_1=N1max. In the general case(N_1<= N1max) the mass ratio distribution can bedetermined for q>q_c, and in favourable cases (if N_1 is sufficientlylarge) for all mass ratios. A first application concerns thePleiades cluster in the colour range 0.2<= B-V<0.98. The concentration of systems near the main sequence in the CMDis used to derive an approximation for the colour-magnitude relation. Asmall positive number c is involved as a parameter. The mass ratiodistribution depends sensitively on c and increases towards small massratios, at least up to q =~ 0.5 and probably up to q =~ 0.3. Thedistribution is bimodal, with a peak at q=1. Photometric arguments showthat c<~ 0.02. A binary frequency of 60-70% as expected from clustersimulations (Kroupa \cite{krou}) requires c<~ 0.03. An adjustment oftwo parameters (c=0.02 and a 70% binary frequency) is sufficient toreproduce the mass ratio distribution for binaries in the galacticfield. This suggests that the mass ratio distribution in the Pleiades issimilar to the distribution in the field, in accordance with aconjecture of Bouvier et al. (\cite{brn}, BRN).
| The Pleiades and alpha Persei Clusters The upper-main-sequence members of the Pleiades and alpha Perseiclusters, considered as members of the Local Association, yield meanparallaxes that are only 4% larger than the mean values from Hipparcosobservations. The (log T_eff, M_V) diagram reveals that in thetemperature range from 6000 to 8000 K, the Hyades and alpha Perseimain-sequence members are nearly identical and several tenths of amagnitude brighter than similar stars on the Pleiades main sequence. Thedeparture of the Pleiades main sequence cannot be traced to either ageor heavy-element abundance differences in the range thought to apply tothese clusters. A 50% increase in the helium abundance of Pleiades overHyades stars could account for the luminosity difference. Alternativeexplanations are that the Pleiades cluster is rejected from superclustermembership and/or that the Hipparcos parallax results for the Pleiadesare in error by some 10%.
| The rotational velocity of low-mass stars in the Pleiades cluster We present new {vsin i} measurements for 235 low-mass stars in thePleiades. The differential rotational broadening has been resolved forall the stars in our sample. These results, combined with previouslypublished measurements, provide a complete and unbiased rotation dataset for stars in the mass range from 0.6 to 1.2{Msun}.Applying a numerical inversion technique on the {vsin i} distributions,we derive the distributions of equatorial velocities for low-massPleiades members. We find that half of the Pleiades dwarfs with a massbetween 0.6 to 1 {Msun} have rotation rates lower than 10{ kms(-1) }. Comparison of the rotational distributions of low-mass membersbetween IC 2602/2391 (~ 35 Myr) and the Pleiades (~ 100 Myr) suggeststhat G dwarfs behave like solid-bodies and follow Skumanich's law duringthis time span. However, comparison between Pleiades and older clusters-M34 (~ 200 Myr) and Hyades (~ 600 Myr)- indicates that the braking ofslow rotators on the early main sequence is weaker than predicted by anasymptotical Skumanich's law. This strongly supports the view thatangular momentum tapped in the radiative core of slow rotators on thezero age main sequence (ZAMS) resurfaces into the convective envelopebetween Pleiades and Hyades age. For the G-dwarfs, we derive acharacteristic coupling time scale between the core and the envelope ofabout 100-200 Myr, which accounts for the observed evolution of surfacerotation from the ZAMS to the Hyades. The relationship between rotationand coronal activity in the Pleiades is in agreement with previousobservations in other clusters and field stars. We show that the Rossbydiagram provides an excellent description of the X-ray activity for allstars in the mass domain studied. The Pleiades data for slow andmoderate rotators fills the gap between the X-ray-rotation correlationfound for slow rotators and the X-ray ``saturation plateau'' observedfor young fast rotators. The transition between increasing X-ray fluxwith rotation and X-ray saturation is observed at log (P/tau)=0.8+/-0.1. These results strengthen the hypothesis that the``saturation'' of the angular momentum loss process depends on thestellar mass. Based on observations collected at the Observatoire deHaute-Provence with ELODIE at the 193cm telescope and with CORAVEL atthe 1m-swiss telescope
| Investigation of the Pleiades cluster. IV. The radial structure On the basis of the best available member list and duplicityinformation, we have studied the radial distribution of 270 stars andmultiple systems earlier than K0 in the Pleiades. Five new long periodspectroscopic binaries have been identified from the CORAVELobservations. We have found a clear mass segregation between binariesand single stars, which is explained by the greater average mass of themultiple systems. The mass function of the single stars and primariesappears to be significantly different. While the central part of thecluster is spherical, the outer part is clearly elliptical, with anellipticity of 0.17. The various parameters describing the Pleiades are(for a distance of 125 pc): core radius rc = 0fdg6 (1.4 pc),tidal radius rt = 7fdg4 (16 pc), half mass radius r_{m/2} =0fdg88 (1.9 pc), harmonic radius /line{r} = 1fdg82 (4 pc). Low-massstars (later than K0) probably extend further out and new proper motionand radial velocity surveys over a larger area and to fainter magnitudeswould be very important to improve the description of the clusterstructure and complete mass function. Based on observations collected atthe Haute-Provence Observatory (France). Table~3 is available only inelectronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://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
| ROSAT Observations of the Pleiades. I. X-Ray Characteristics of a Coeval Stellar Population Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJS..102...75M&db_key=AST
| High-precision positions and proper motions of 441 stars in the Pleiades astrometric standard region. Not Available
| 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.
| Membership probabilities in the Pleiades field. A catalogue of proper motions and photographic B, V magnitudes for starsup to B=19mag within a region centered near Alcyone is presented. Thecatalogue is based on MAMA measurements of 8 plates taken with theTautenburg Schmidt telescope. The survey includes ca. 14500 stars andcovers a total field of about 9 square degrees. For stars brighter thanB=18mag an internal accuracy of 0.05mag and 2.5mas/year has beenestimated for photometric data and proper motions, respectively.Membership probabilities, proper motions and B, V magnitudes are listedfor 442 stars up to B=19mag in the Pleiades field.
| Radio continuum emission from stars: a catalogue update. An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
| The evolution of the lithium abundances of solar-type stars. III - The Pleiades New measurements of lithium in more than 100 Pleiades F, G, and K dwarfsare reported. Abundances are determined from spectrum synthesis fits tothe data as well as from use of new covers of growth from the Li 6708-Afeature. It is argued that most Late-F and early-G dwarfs in thePleiades are consistent with the tight N(Li) vs mass relation seen inthe Hyades in the same mass range. Most Li-rich stars have abundances ator near the primordial level for Population I, and none exceed thatlevel by a significant amount. At any given color the stars that rotatefast have the most Li and have the strongest chromospheric activity.Ways in which an apparent spread in N(Li) could arise from anintrinsically tight n(Li)-mass relation are considered, and it isconcluded that the spread is probably real and is not an artifact ofline formation conditions or inhomogeneous atmospheres on the stars.
| Rotation and chromospheric emission among F, G, and K dwarfs of the Pleiades High-resolution echelle spectra of more than 100 F, G, and K dwarfs inthe Pleiades are reported. Chromospheric activity in these stars ismeasured via comparisons of the profiles of H-alpha and the Ca II IRtriplet to chromospherically inactive field stars. Consistent dereddenedcolors are determined from the available photometry and temperatures arederived. Most G and K dwarfs in the Pleiades rotate slowly, but about 20percent of the stars are ultrafast rotators (UFRs). That fraction ofUFRs is independent of color, and the highest rotation rates are foundamong the K dwarfs. The Pleiades exhibit a broad range in the strengthof chromospheric emission at any one color. Most G and K dwarfs in thePleiades show H-alpha and the IR triple in absorption, with filling inof the line cores.
| The consistency of Stromgren-beta photometry for northern galactic clusters. I - The Hyades and Coma We have compared the Hyades, Coma, and a set of field standard stars inthe V and Stromgren-beta systems. If Stromgren data by Crawford and hiscollaborators (1966, 1969, 1970) are considered, all the data turn outto be on the same system; no corrections as large as several mmag arerequired to achieve this state. For beta, similar consistency betweenthe Hyades and Coma is already known to exist. We find that for thestandard stars, beta values from the literature are consistent with theHyades-Coma system. For V, we adopt corrections derived previously byJoner and Taylor (1990) for published cluster photometry. Given thesecorrections, we find that within rather generous accidental-errorlimits, the V systems for the field stars and the clusters agree.
| 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.
| Radial velocity measurements in the Pleiades High-resolution radial velocities for 71 stars of both early and latespectral types in the Pleiades cluster have been obtained in order toinvestigate the possibility of establishing an early-type star velocitysystem by bootstrapping late-type velocity standards to early-type onesin young clusters. It is shown that in the absence of early-typevelocity standards the velocity scale of the early-type spectra in thecluster can be tied into the IAU velocity system by examining thevelocity distributions of both the early-type and the late-type stars,since the internal velocity dispersion in an open cluster is less thanabout 1 km/s. It is found that the cluster velocity of the Pleiades is6.0 km/s, with an observed velocity dispersion of 1 km/s. Based on thesevelocity results, a list of potentially constant velocity B and A starsis proposed for further studies to confirm the constancy of theirvelocities.
| CA II H and K measurements made at Mount Wilson Observatory, 1966-1983 Summaries are presented of the photoelectric measurements of stellar CaII H and K line intensity made at Mount Wilson Observatory during theyears 1966-1983. These results are derived from 65,263 individualobservations of 1296 stars. For each star, for each observing season,the maximum, minimum, mean, and variation of the instrumental H and Kindex 'S' are given, as well as a measurement of the accuracy ofobservation. A total of 3110 seasonal summaries are reported. Factorswhich affect the ability to detect stellar activity variations andaccurately measure their amplitudes, such as the accuracy of the H and Kmeasurements and scattered light contamination, are discussed. Relationsare given which facilitate intercomparison of 'S' values with residualintensities derived from ordinary spectrophotometry, and for convertingmeasurements to absolute fluxes.
| Lithium, age, and metallicity in open clusters It is shown that a strong relationship exists between Li abundance andage for stars in the temperature region 5950-6350 K. The relation isderived from mean Li abundances in eight open clusters ranging in agefrom 5 x 10 to the 7th to 8 x 10 to the 9th yr. The Li declinesexponentially with t exp(-0.3). It is suggested that, in thistemperature regime, simple microscopic diffusion is the cause of the Lidepletion. It is possible that there is a metallicity term in therelation, such that higher metallicity clusters with deeper convectionzones have less Li depletion, while lower metallicity cluster undergogreater depletion. This is consistent with expectations from diffusiontheory. Furthermore, the halo stars, with even lower metallicity andshallower convection zones, would have more diffusion and more Lidepletion; this is in agreement with recent theoretical work.
| X-ray studies of coeval star samples. II - The Pleiades cluster as observed with the Einstein Observatory Coronal X-ray emission of the Pleiades stars is investigated, andmaximum likelihood, integral X-ray luminosity functions are computed forPleiades members in selected color-index ranges. A detailed search isconducted for long-term variability in the X-ray emission of those starsobserved more than once. An overall comparison of the survey resultswith those of previous surveys confirms the ubiquity of X-ray emissionin the Pleiades cluster stars and its higher rate of emission withrespect to older stars. It is found that the X-ray emission from dA andearly dF stars cannot be proven to be dissimilar to that of Hyades andfield stars of the same spectral type. The Pleiades cluster members showa real rise of the X-ray luminosity from dA stars to early dF stars.X-ray emission for the young, solarlike Pleiades stars is about twoorders of magnitude more intense than for the nearby solarlike stars.
| Lithium in old open clusters - NGC 188 Echelle spectra which include the Li I line at 6707 A are reported forseven main-sequence stars and one subgiant in NGC 188. The Li I line isdetected in five of the six dwarfs which are highly probable clustermembers. The derived atmospheric Li/H ratios exceed the solar value byfactors ranging approximately from 10 to 40, although these apparentlyclosely solarlike stars are about twice as old as the sun. The variationof the lithium abundance with stellar mass along the main sequences ofthe Pleiades, the Hyades, NGC 752, and NGC 188 are compared. Theresulting evolutionary pattern indicates that the lithium fraction inthe Galactic gas has shown no appreciable change from Li/H of roughly 10to the -9th since the birth of NGC 188 about 10 Gyr ago, except that theabundance could have been higher by an uncertain but possiblyappreciable factor at the beginning of that epoch.
| Lithium in the Pleiades and Alpha Persei clusters Observations of the Li region in the 23 F dwarfs of the Pleiades andAlpha Per clusters were performed with a TI CCD at the coudespectrographof the 200-inch telescope with a spectral resolution of 0.2 A and 2sigma signal-to-noise ratios of 100-300. All 21 of the stars observed inthe temperature region of 6100-7300 K show strong Li I lines with valuesof log N(Li) near 3.0; the mean is 2.98 + or - 0.13. The data suggestthat the significant decrease in surface Li, possibly caused bydiffusion or differential rotation, occurs for cluster stars between theages of 5 x 10 to the 7th to 5 x 10 to the 8th yr.
| Interstellar extinction in the direction of the Merope dark cloud in Pleiades The dependence of interstellar extinction on distance in the directionof the dark cloud south of Merope is determined using photoelectricphotometry of 93 stars in the Vilnius photometric system. The cloudfront edge is detected at 120-130 pc from the sun, and the distance ofthe Pleiades cluster is found to be 127 pc. Mean extinction, A(V), inthe Merope cloud is of the order of 1.0 mag. There is no evidence ofextinction at distances exceeding the Merope cloud distance. Thevariable extinction method yields R = A(V)/E(B-V) = 3.6, while themaximum polarization wavelength method gives the value 3.4. SomePleiades stars are suspected to be unresolved binaries.
| VBLUW observations of Pleiades G and K dwarfs Photometric observations of 45 G and K dwarfs in the Pleiades cluster,obtained using the VBLUW photometer and a 16.5-arcsec diaphragm on the91-cm Dutch telescope at ESO during 1980-1981, are reported. The dataare presented in tables and briefly characterized. Light curves areprovided for 11 variable stars, and features indicating surface fluxdistributions which are not axially symmetric are noted, along withrotational light variations like those of BY Dra. The photometricperiods are found to be in good agreement with the rotational periods,and possible reasons why no periods were found between 0.6 and 6.0 d arediscussed.
| The Pleiades cluster. III - Polarization, reddening, and the unusual distribution of interstellar matter A polarization survey of Pleiades cluster members and nonmembers hasbeen carried out together with a determination of interstellar reddeningfor cluster members. The ISM in front of and inside the cluster leads tovariable polarization and reddening across the cluster. The optical datacorrelate well with available radio and millimeter features. Twodistinct ISM concentrations are isolated: (1) a uniform foreground sheetin front of the whole cluster which is seen as constant reddening andpolarization in the eastern part of the cluster; and (2) additionalintracluster material, located mainly in the western part of thecluster.
| The distance of the Pleiades cluster and the calibration of photometric luminosities for early-type stars An examination of the lower main-sequence (mode-A) stars in the Pleiadescluster suggests an Fe/H abundance ratio between 0.0 and 0.1 dex with aresulting modulus of 5.65 + or - 0.1 mag, and fundamental defects in thecalculation of Balona and Shobbrook (1984), with an adopted modulus of5.50 mag, are discussed. It is suggested that the ZAMS of Balona andShobbrook, and of Mermilliod (1981), are too bright due to theirassumption that the color-luminosity arrays of such clusters as thePleiades represent isochrones, leading to uncertainties in the ZAMS,particularly with respect to slope. Several recently publishedphotometric luminosity calibrations for early-type stars may beincorrect due to their failing to recognize the probable presence of atleast two evolutionary modes and the apparent absence of ZAMS stars nearthe sun.
| A VBLUW photometric survey of the Pleiades cluster Photometric data are presented for 390 known or suspected members of thePleiades cluster. The data were obtained in 1979 at ESO using theWalraven VBLUW photometer and the Dutch 91-cm telescope. A comparisonwas made with subsets obtained with the same telescope andinstrumentation at the former Leiden Southern Station at the SAAO annexduring 1976 and 1977, and with data obtained at ESO during 1980 and1981. The much improved performance of the telescope and the photometerat their new site is obvious from these comparisons. The stars measuredcomprise the selection of possible members by Hertzsprung (1947)brighter than m(pg) = 14.5 and a selection of possible members in theouter region of the cluster by Pels et al. (1975). Of the starsselected, 66 were found not to be members. A few of these are possiblyescaping members. The present data set provides a well determined mainsequence over the range K2V to B9V, as well as data on some of theprobably premain-sequence K2-to-K5 and postmain-sequence B8-to-B6 stars.Finding charts for the stars selected by Pels are presented in anappendix.
| The Pleiades cluster. I - Polarization and reddening of the brighter stars New linear polarization values have been measured for the brightPleiades stars at an accuracy level of 0.0001. Suspicions in theliterature concerning a high incidence of intrinsic polarization are notconfirmed. Multiple measurements show no (or very little) evidence forpolarization variability. The critical polarization/extinction ratio iscompatible with an interstellar origin, while any unusual individualvalues are not statistically significant. The average ratio of blue tovisual polarization is also consistent with an interstellar origin ofpolarization. Despite the small size of the polarization values, anexcellent agreement with the average values measured by Markkanen (1977)is found.
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Observation and Astrometry data
Constellation: | Taurus |
Right ascension: | 03h43m42.88s |
Declination: | +23°35'41.2" |
Apparent magnitude: | 9.561 |
Proper motion RA: | 21.4 |
Proper motion Dec: | -45.6 |
B-T magnitude: | 10.137 |
V-T magnitude: | 9.609 |
Catalogs and designations:
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