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Classification of Spectra from the Infrared Space Observatory PHT-S Database
We have classified over 1500 infrared spectra obtained with the PHT-Sspectrometer aboard the Infrared Space Observatory according to thesystem developed for the Short Wavelength Spectrometer (SWS) spectra byKraemer et al. The majority of these spectra contribute to subclassesthat are either underrepresented in the SWS spectral database or containsources that are too faint, such as M dwarfs, to have been observed byeither the SWS or the Infrared Astronomical Satellite Low ResolutionSpectrometer. There is strong overall agreement about the chemistry ofobjects observed with both instruments. Discrepancies can usually betraced to the different wavelength ranges and sensitivities of theinstruments. Finally, a large subset of the observations (~=250 spectra)exhibit a featureless, red continuum that is consistent with emissionfrom zodiacal dust and suggest directions for further analysis of thisserendipitous measurement of the zodiacal background.Based on observations with the Infrared Space Observatory (ISO), aEuropean Space Agency (ESA) project with instruments funded by ESAMember States (especially the Principle Investigator countries: France,Germany, Netherlands, and United Kingdom) and with the participation ofthe Institute of Space and Astronautical Science (ISAS) and the NationalAeronautics and Space Administration (NASA).
| STELIB: A library of stellar spectra at R ~ 2000
We present STELIB, a new spectroscopic stellar library, available athttp://webast.ast.obs-mip.fr/stelib. STELIB consists of an homogeneouslibrary of 249 stellar spectra in the visible range (3200 to 9500Å), with an intermediate spectral resolution (la 3 Å) andsampling (1 Å). This library includes stars of various spectraltypes and luminosity classes, spanning a relatively wide range inmetallicity. The spectral resolution, wavelength and spectral typecoverage of this library represents a substantial improvement overprevious libraries used in population synthesis models. The overallabsolute photometric uncertainty is 3%.Based on observations collected with the Jacobus Kaptein Telescope,(owned and operated jointly by the Particle Physics and AstronomyResearch Council of the UK, The Nederlandse Organisatie voorWetenschappelijk Onderzoek of The Netherlands and the Instituto deAstrofísica de Canarias of Spain and located in the SpanishObservatorio del Roque de Los Muchachos on La Palma which is operated bythe Instituto de AstrofÃsica de Canarias), the 2.3 mtelescope of the Australian National University at Siding Spring,Australia, and the VLT-UT1 Antu Telescope (ESO).Tables \ref{cat1} to \ref{cat6} and \ref{antab1} to A.7 are onlyavailable in electronic form at http://www.edpsciences.org. The StellarLibrary STELIB library is also available at the CDS, via anonymous ftpto cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/402/433
| 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/.
| UBV photometry of Galactic foreground and LMC member stars - III. LMC member stars - a new data base
New UBV photometry for 878 luminous member stars of the Large MagellanicCloud (LMC) and 13 stars of uncertain membership is presented. The datawill be available at Centre de Données astronomiques deStrasbourg. Including former observations now UBV data are available foraltogether 2470 luminous LMC stars and 2106 foreground stars plus 65stars of uncertain membership. The observations have been used alreadyfor several investigations dealing e.g. with interstellar reddeninglines and intrinsic colours, the dust distribution and the calibrationof charge-coupled device exposures.
| Red supergiants in the LMC - IV: Calibration of intrinsic colours and the HRD
A new calibration of the (B-V)0, (V-R)0 and(V-I)0 colours in the Kron-Cousins system for F to Msupergiants and of the (V-K)0 colours in the SAAO system of Kto M supergiants in the LMC as measures of effective temperature andbolometric correction is given. For F to G supergiants the theoreticalTeff-intrinsic colour- relations given by Lejeune et al.(1997) on the basis of their own model atmospheres agree mostly wellwith our observations. For K to M supergiants, however, their intrinsiccolours are too red in most cases. The relations given by Bessell et al.(1998) based on the model atmospheres of Plez (1997) fit theobservations better, but their synthetic colours are often also too red.The calibration of the bolometric correction is not reproduced well byany of the models. The HRD of the stars shows two distinct groups, onewith log Teff above 3.80 and one with log Teffbetween 3.53 and 3.62. The upper luminosity and therefore the mass limitdepends significantly on effective temperature. The F to G stars haveMbol up to -9.8 mag (corresponding to 45 Msun),while the K to M stars do not exceed - -9.0 mag (corresponding to 31Msun). Neither the Geneva nor the Padova models can fit thepositions of the most luminous and the coolest supergiants. Thediscrepancy between theory and observation increases both withincreasing mass loss rate and overshooting. Best agreement with theobservations is reached by assuming mass loss rates of 2/3 of the deJager et al. (1988) mass loss rates. As shown both by the luminosity andinitial mass function, very luminous (i.e. massive) stars areoverproportionally rare. With -3.73 +/- 0.20 the slope of the initialmass function is very steep in the considered range of 16-35Msun, but confirms the results obtained by Massey et al.(1995) from an extensive study of the field OB stars both in theMagellanic Clouds and the Galaxy.
| HIPPARCOS photometry of 24 variable massive stars (alpha Cygni variables)
The photometric variability of 24 alpha Cyg variables, i.e. variablesuper-and hypergiants, observed by the Hipparcos satellite is described.Three of the selected stars are situated in the SMC, 12 in the LMC andthe remaining 9 in the Galactic plane. Four of them are hot S Dor-typevariables, or LBVs (luminous blue variables) and two are possiblemembers of this class. Light curves are presented for all stars. Forfive stars, among which one LBV, the variability was discovered from theHipparcos photometric data. Results of period searches are presentedand, when relevant, folded light curves are shown. The linear ephemerisof two variables was revised. For most of the program stars theHipparcos magnitude scale (Hp) differs from the V of the UBV system byla 0fm1 . For all variables temperatures and M_bol are given. Galacticforeground reddening for the objects in the Magellanic Clouds are givenbased on IRAS maps.
| The yellow hypergiants
We list the main stellar data of known hypergiants and similarlyluminous stars, and then concentrate on a review of the yellowhypergiants. These stars are post-red supergiants evolving alongblueward loops in the Hertzsprung-Russell diagram. Their properties,their location in the Hertzsprung-Russell diagram and their occasionalmass ejections are related to a region of atmospheric instability in theH-R diagram, the Yellow Void. The `bouncing against the border of theVoid' of three objects: ρ Cas, HR8752 and IRC+10420, is described.The apparent atmospheric instability of yellow hypergiants is related tothe atmospheric pulsations. There are indications that the approach tothe Void is associated with an increased amplitude of the pulsation andwith enhanced mass loss. The observed small-scale motion field is onlyapparently strongly supersonic; the observed large stochastic velocitiesare the quasi-stochastically varying thermal motions in the many hotsheets that occur in the wakes of many small shocks, while the realhydrodynamic velocity component is small and subsonic. This shock-wavefield is also responsible for the observed rate of mass loss and foremission in the wings of Hα . Most yellow hypergiants haveenvelopes containing gas and dust, but a thick extended envelope,presumably dissipating and showing bipolar outflow, is only known aroundIRC+10420. At the interface of the bipolar wind and the interstellarmedium one or more stationary shocks may develop as is observed in thecase of IRC+10420 and suspected with ρ Cas.
| 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
| Carbon, nitrogen, oxygen and lithium abundances of six cool supergiants in the SMC.
Carbon, nitrogen and oxygen abundances were derived from high-resolutionspectra of 6 cool supergiants of the Small Magellanic Cloud.Oxygen-to-iron ratios (mean value <[O/Fe]>=~-0.18dex) are found tobe similar to those found in young objects in the LMC and the Galaxy.This result is discussed in terms of chemical evolution. A meandeficiency of the carbon-to-iron ratio of <[C/Fe]>=~-0.3dex and anitrogen-to-iron ratio <[N/Fe]>=~+0.22dex might imply a mixingsignature, which is confirmed by the low ^12^C/^13^C ratio measured inthree stars. In terms of chemical evolution, carbon plus nitrogenabundances have to be considered: in our sample, a mean value of<[(C+N)/Fe]>=~-0.15dex indicates a slight deficiency in carbonplus nitrogen with respect to the Sun, similar to the deficiencies foundin Galactic supergiants and Orion. Lithium has been detected in all theprogram stars, reaching ɛ(Li)=0.6dex for two stars.
| The HIPPARCOS proper motion of the Magellanic Clouds
The proper motion of the Large (LMC) and Small (SMC) Magellanic Cloudusing data acquired with the Hipparcos satellite is presented. Hipparcosmeasured 36 stars in the LMC and 11 stars in the SMC. A correctlyweighted mean of the data yields the presently available most accuratevalues, mu_alpha cos(delta) = 1.94 +/- 0.29 mas/yr, mu_delta = - 0.14+/- 0.36 mas/yr for the LMC. For the SMC, mu_alpha cos(delta) = 1.23 +/-0.84 mas/yr, mu_delta = - 1.21 +/- 0.75 mas/yr is obtained, whereby careis taken to exclude likely tidal motions induced by the LMC. Bothgalaxies are moving approximately parallel to each other on the sky,with the Magellanic Stream trailing behind. The Hipparcos proper motionsare in agreement with previous measurements using PPM catalogue data byKroupa et al. (1994), and by Jones et al. (1994) using backgroundgalaxies in a far-outlying field of the LMC. For the LMC the Hipparcosdata suggest a weak rotation signal in a clockwise direction on the sky.Comparison of the Hipparcos proper motion with the proper motion of thefield used by Jones et al. (1994), which is about 7.3 kpc distant fromthe center of the LMC, also suggests clockwise rotation. Combining thethree independent measurements of the proper motion of the LMC and thetwo independent measurements of the proper motion of the SMC improvesthe estimate of the proper motion of the LMC and SMC. The correspondinggalactocentric space motion vectors are computed. Within theuncertainties, the LMC and SMC are found to be on parallel trajectories.Recent theoretical work concerning the origin of the Magellanic Systemis briefly reviewed, but a unique model of the Magellanic Stream, forthe origin of the Magellanic Clouds, and for the mass distribution inthe Galaxy cannot yet be decided upon. Future astrometric space missionsare necessary to significantly improve our present knowledge of thespace motion of the two most conspicuous galactic neighbours of theMilky Way.
| New discoveries on the S DOR phenomenon based on an investigation of the photometric history of the variables AG Car, S DOR and Eta Car.
A century of photometric observations of AG Car and S Dor isinvestigated for general characteristics and possible periodicities inthe occurrence of the S Dor (SD) phases, defined as episodes of a radiusand an apparent brightness variation at a more or less constantluminosity. We identified two types of such phases: the``very-long-term" (VLT) and the ``normal" SD phases. The latter aresuperimposed on the first. The time scales for the VLT-SD phases are inthe order of decades for both variables. The normal SD phases of AG Carand presumably also of S Dor obey stable periods of 371.4d +/-0.6d and6.8+/-0.1yr, respectively. We suspect that the SD-, or LBV phenomenon isprovoked by two types of pulsational modes. The oscillating O-C valuesfor both variables indicate the possible presence of beat cycles. Theirtime scales are of the order of years to decades. We found, at least forthe SD activity of AG Car, further support for a radius change of thestar and a more or less horizontal displacement in the theoreticalHR-diagram. However, S Dor has a higher luminosity in minimum than inmaximum, amounting to 0.5-1mag depending on the range in the visualmagnitude (1-2.4mag). Inconsistencies between existing temperaturescales during the light variations of AG Car were noticed. We found nocyclic pattern whatsoever in the SD phases of Eta Car. The time scalefor such events within the last 20yr lies between 1 and 3yr. There isevidence that over the last 20 yrs the central LBV in the Eta Car systemexperienced a rising branch of a VLT-SD phase, which appears to furnish,according to the secular colour change, indirect support for an ongoingdecrease of the circumstellar dust density.
| A uvbyβ photometric calibration of iron abundances in supergiant stars.
A photometric reddening-free calibration for [Fe/H] valid for giant andsupergiant stars of intermediate temperature, has been obtained usingthe Stroemgren uvbyβ system. Galactic supergiants, supergiants inthe Magellanic Clouds and Galactic metal deficient red giants withspectroscopic determinations of [Fe/H] were used as calibrators. Thecalibration can be used to predict [Fe/H] with an accuracy of 0.33 dex,valid for stars with 0.14<[m_1_]<0.70 in the iron abundance range-2.5<[Fe/H]<+0.3. This shows the potential of supergiant stars astracers of iron abundances in other galaxies. Evidence that Galacticluminous F-G stars are intrinsically bluer than their counterparts inthe Magellanic Clouds is offered.
| Carbon abundances in the LMC globular cluster NGC 1818.
From medium-resolution spectra (~5A) of 5 red supergiants in theglobular cluster NGC 1818 of the Large Magellanic Cloud, we have derivedtheir metallicities through a comparison to a grid of 380 syntheticspectra (Cayrel et al. 1991). The carbon abundances were then derived bycomputing synthetic spectra in the G-band region. A mean metallicity forthe 5 stars is [Fe/H]=~-0.9. The mean carbon abundance isɛ(C)=7.9 for 4 stars, and a lower value of ɛ(C)=7.2 forthe star B26, for which a convective mixing, or exchange of materialwith a companion has possibly occurred.
| Oxygen abundances in the large magellanic cloud: A prediction of SN II/SN I rates
Using the O I lambda 615.8 nm line we have derived the oxygen abundancesfor two stars of the large magellanic cloud (LMC). Available oxygenabundances in the literature are given for another nine stars. Thesedata points are compared to predictions of epsilon(O) vs. epsilon(Fe),based on planetary nebulae data, showing good agreement. These resultsseem to point to a relative higher contribution of SN Ia in the yieldsthan that observed in the Galaxy.
| On the motion of the Magellanic Clouds
We have measured the proper motion of the Large and Small MagellanicClouds using Magellanic Cloud stars in the PPM Catalogue, and obtainμ = 1.7+/-0.9 mas yr^-1^ for the LMC. Systematic uncertainties arediscussed. Bound and unbound orbits of the Magellanic Clouds around theGalaxy are consistent with our result. The various models of theMagellanic Stream and their predictions for the motion of the MagellanicClouds are discussed. The predictions by several authors for the sametype of model differ by up to 0.3 mas yr^-1^. All models proposed todate that assume the Magellanic Clouds to lead the Magellanic Streampredict a proper motion for the LMC of between 1.5 and 2.0 mas yr^-1^,the smallest value being a prediction for a Galaxy with no halo. Otherindependent measurements of the proper motion of the LMC are discussed.These lie between 1 and 1.5 mas yr^-1^. Future astrometry will have toallow measurement of the proper motion of the LMC with an uncertainty nolarger than one-tenth of a milliarcsecond per year in order to help todistinguish significantly between models of the halo of the Galaxy. Theproper motion of the LMC cannot by itself distinguish between models ofthe Magellanic Stream.
| Luminosities of yellow supergiants from near-infrared spectra - Calibration through Magellanic Cloud stars
The possibility of using medium resolution spectrograms in the nearinfrared region to determine luminosities of A-G supergiants has beenexplored. A sample of 49 of these stars has been observed in the twoMagellanic Clouds, and using the intensities of the O I 7774 triplet andan index (CP), which is a combination of the Ca II triplet and Paschenlines intensities, a preliminary luminosity calibration, based on LMCstars, has been obtained. Such a calibration predicts reliableluminosities for Galactic supergiants, and offers the advantage of beingcompletely reddening independent. The reddening free CP index combinedwith BVRI color indices has also been used to estimate the interstellarreddenings of Magellanic Cloud stars.
| The chemical composition of Magellanic Cloud Cepheids and nonvariable supergiants
Results of abundance analyses of 14 Cepheids and nonvariable supergiantsin the Magellanic Clouds are presented along with comparison data onfour Galactic objects. Elemental abundances derived include Li, C, N, O,the alpha-elements, the Fe peak, and limited data on the heavy elements.Only HV 5497 in the LMC shows any detectable Li among the Cloud objects.The present CNO data, when combined with previous results, suggest adisparity between the LMC and the SMC supergiants in that the SMC starshave an essentially constant O/Fe ratio, while the LMC stars do not. TheO/Fe ratios within both Clouds are lower than the ratio found inGalactic stars of similar metallicity, but are comparable to the O/Feratios found in Galactic supergiants. For heavier elements, previousresults which indicate the light s- and r-process elements (Sr, Y, Zr)show Galactic ratios with respect to Fe, but that the heavy s- andr-process elements (Ba-Sm) are enhanced in the Clouds, are confirmed.
| Positional reference stars in the Magellanic Clouds
The equatorial coordinates are determined of 926 stars (mainly ofgalactic origin) in the direction of the Magellanic Clouds at the meanepoch T = 1978.4 with an overall accuracy characterized by the meanvalues of the O-C coordinates, Sa = 0.35 arcsec and Sd = 0.38 arcsec,calculated from the coordinates of the Perth reference stars. Thesevalues are larger than the accuracy expected for primary standard stars.They allow the new positions to be considered as those of reliablesecondary standard stars. The published positions correspond to anunquestionable improvement of the quality of the coordinates provided inthe current catalogs. This study represents an 'astrometric step' in thestarting of a 'Durchmusterung' of the Magellanic Clouds organized by deBoer (1988, 1989).
| The distance to the Magellanic Clouds from luminous F supergiants
A recent M(v)-uvby beta calibration for Galactic luminous F-Gsupergiants was used to estimate the distance to the Magellanic Cloudsfrom F supergiants. The distance moduli 19.33 + or - 0.31 for the SMCand 18.19 + or - 0.22 for the LMC are found. The present limitations ofusing F-G supergiants as distance indicators are discussed.
| Observations of the new luminous blue variable R 110 of the Large Magellanic Cloud during an F star-phase
The photometric as well as low-dispersion and high-dispersionspectroscopic data of the Large Magellanic Cloud star R 110 is analyzed.The photometric data indicate that the energy distribution of R 110 isdifferent from than one of a normal supergiant. Stellar parameters arediscussed, and the continuum energy distribution is examined andcompared with that one of R 127 and a theoretical model. It is pointedout that the comparatively low mass indicates that R 110 is in itspostred supergiant evolutionary phase, and that the star shows noevidence of an enhanced mass-loss rate during its visual brightening.Since the amplitude of the visual brightness variations is comparativelysmall, it is suggested that the bolometric correction of the star didnot change very much, which is consistent with all observations.
| 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.
| Light variations of massive stars (Alpha Cygni variables). X - The F type supergiants G266 = HDE271182 = R92 and G322 = HDE269612 in the LMC
The results of VBLUW photometric observations of two massive variablestars in the LMC, the hypergiant G266 = HDE271182 = R92 (F8Ia/+/) andthe supergiant G322 = HDE269612 (FoIa) are presented and compared tothose for HD33486 star. Evidence is presented that indicates that thesemassive objects are no Cepheids, as was suggested by Grieve et al.(1985), but are Alpha Cyg variables. The highly unstable periods andlight curves recorded for both variables suggest that the observedinstability must be caused by a mechanism different from that acting inCepheids. The progressive change of light amplitudes and quasi-periodsfor massive stars from the left-hand to the right-hand side of the HRdiagram (Genderen, 1989) strongly suggests an evolutionary sequence fromO-type to G-type supergiants.
| Abundances of the heavy elements in the Magellanic Clouds. I - Metal abundances of F-type supergiants
Metal abundances of eight F-type supergiants in each of the MagellanicClouds were determined using the results of high-resolution spectroscopyanalysis of these stars, together with new Stromgren uvby and Cousins(1980) BVRI photometry. It was found that the mean Fe abundance (Fe/H)for the SMC is -0.65 + or - 0.2 dex, and the mean Fe abundance for theLMC is -0.30 + or - 0.2 dex. The abundances of stars in both the SMC andLMC appear relatively uniform, and the abundances of the elementsrelative to Fe are very similar in both Magellanic Clouds and in Canopus(the carbon-to-iron abundances are the same for all three). It was alsofound that Nd and Sm are overabundant in both clouds, supporting thetrends found by Spite et al. (1988) for the three SMC stars theystudied.
| A list of MK standard stars
Not Available
| The maximum amplitude of the optical micro-variations of massive O-F type stars (or Alpha Cygni variables, including LBV's or S DOR variables) across the HR diagram
The maximum light amplitude (MLA) of the microvariations of nearly 100massive stars with spectral type O 3-F8 are collected from theliterature and unpublished material. These variables, called the AlphaCygni variables, also include the LBVs or S Dor type variables. The SDor type variables must be in a quiescent stage to detect theirintrinsic variations properly. The log T(eff)/MLA diagram exhibits aclear separation between S Dor type variables and the normal Alpha Cygnivariables (the majority). The results suggest that the outer layers ofboth types of stars where gravity waves presumably occur, differphysically from each other.
| 1988 Revised MK Spectral Standards for Stars GO and Later
Not Available
| CO overtone emission from Magellanic Cloud supergiants
A sample of 63 high-luminosity LMC supergiants has been searched forfirst-overtone CO emission at 2.3 microns. Six new CO emission starshave been found, showing that CO first-overtone emission is a commoncharacteristic of luminous stars with dense circumstellar envelopes andhaving a wide range of stellar temperatures. Of the non-CO emissionstars, eight have strong He I emission. Nine stars show CO absorption at2.3 microns from late-type companions. CO emission was not found in anyof the three LMC S Doradus variables, and the stars which do show COemission are not known to be photometrically variable.
| Mass loss rates in the Hertzsprung-Russell diagram
Mass loss rates have been collected for 271 stars of spectral type Othrough M, primarily of population I. Good agreement is found forresults obtained according to six different methods, and it is shownthat the mass loss rate data can be well represented by one empiricalinterpolation formula as a function of the effective temperature andluminosity. The chemically evolved stars are shown to have mass lossrates which are larger than those of normal stars occupying the samepositions in the Hertzprung-Russell diagram by factors of 160 forWolf-Rayet stars and 11 for C-type stars.
| UBV photoelectric catalogue (1986). II - Analysis
The UBV photoelectric data of the stars presenting several entries inthe 1986 edition of the UBV catalog have been systematicallyintercompared, and this paper presents a discussion of the stars forwhich discrepancies larger than 0.2 mag were found. Thirty-six probablyvariable stars have been detected, among which 18 are Be stars. Sixtyfurther stars present differences in the V magnitude larger than 0.2mag. Sixteen stars already appear in the NSV catalog. Although manyproblems are probably due to poor observations, new (eclipsing) variablestars may be found in this sample. Complete disagreement is foundbetween the values published from two independent sources in 34 cases. Afirst analysis of the quality of the UBV data shows that 65 percent ofthe differences in the V magnitude and in U-B color, for respectively11,500 and 7200 stars with two sources of data, are smaller than 0.04.The scatter on the B-V index appears to be smaller, since the samepercentage reaches 79 percent.
| UBV Photoelectric Photometry Catalogue (1986). III Errors and Problems on DM and HD Stars
Not Available
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