Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars
This paper presents the catalogue and the method of determination ofaveraged quadratic effective magnetic fields < B_e > for 596 mainsequence and giant stars. The catalogue is based on measurements of thestellar effective (or mean longitudinal) magnetic field strengths B_e,which were compiled from the existing literature.We analysed the properties of 352 chemically peculiar A and B stars inthe catalogue, including Am, ApSi, He-weak, He-rich, HgMn, ApSrCrEu, andall ApSr type stars. We have found that the number distribution of allchemically peculiar (CP) stars vs. averaged magnetic field strength isdescribed by a decreasing exponential function. Relations of this typehold also for stars of all the analysed subclasses of chemicalpeculiarity. The exponential form of the above distribution function canbreak down below about 100 G, the latter value representingapproximately the resolution of our analysis for A type stars.Table A.1 and its references are only available in electronic form atthe 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/407/631 and Tables 3 to 9are only available in electronic form at http://www.edpsciences.org
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Hβ photometry of southern CP2 stars: is the uvbybeta luminosity calibration also valid for peculiar stars?
We present Hβ photometry of 233 southern CP2 stars (covering themagnetic Ap stars according to the definition by Preston 1974) brighterthan V < 8.5 mag from the list of Bidelman & MacConnell (1973).Absolute magnitudes derived from this photometry together with alreadyexisting uvby photometry is confronted with Hipparcos results availablefor a common subset of 152 stars. In order to compare peculiar withnormal stars, we identified a sample of 1147 normal B to F-type starsusing their published uvbybeta and Hipparcos data. For our analysis wedivide both samples into three temperature as well as two Hipparcosparallax accuracy groups. The error distribution of both samples provedto be statistically comparable. As a result the absolute magnitudes forthe B-type CP2 stars show up to be significantly too bright by anaverage of 0.5 mag using the actual photometric calibration. On theother hand, the photometric absolute magnitudes for cool A to F-type CP2stars are up to three magnitudes fainter as compared to Hipparcos. Basedon observations at ESO-La Silla and with the Hipparcos satellite
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A Search for Helium Spectrum Variables
Not Available
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The Scorpius OB2 Complex
The Sco OB2 complex is a member of the Local Association. Theassociation contains pre-main-sequence stars in addition to objects some3 x 10^7 yr old. If it is assumed that stars in wide binaries arecoeval, then the He-weak variables in the supercluster arepre-main-sequence, elevated above that sequence by an amount similar tothat of the 3 x 10^7 yr old, normal stars but contracting toward thesequence, not evolving from it. The apparent great depth of theassociation is probably a result of some foreground superclustermembers, superposed on Sco OB2, and a rift in the absorption cloudbetween Scorpius and Ophiuchus. The adjoining Chamaeleon complex alsoappears to be a member of the supercluster.
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On the HIPPARCOS photometry of chemically peculiar B, A, and F stars
The Hipparcos photometry of the Chemically Peculiar main sequence B, A,and F stars is examined for variability. Some non-magnetic CP stars,Mercury-Manganese and metallic-line stars, which according to canonicalwisdom should not be variable, may be variable and are identified forfurther study. Some potentially important magnetic CP stars are noted.Tables 1, 2, and 3 are available only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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The observed periods of AP and BP stars
A catalogue of all the periods up to now proposed for the variations ofCP2, CP3, and CP4 stars is presented. The main identifiers (HD and HR),the proper name, the variable-star name, and the spectral type andpeculiarity are given for each star as far as the coordinates at 2000.0and the visual magnitude. The nature of the observed variations (light,spectrum, magnetic field, etc.) is presented in a codified way. Thecatalogue is arranged in three tables: the bulk of the data, i.e. thosereferring to CP2, CP3, and CP4 stars, are given in Table 1, while thedata concerning He-strong stars are given in Table 2 and those foreclipsing or ellipsoidal variables are collected in Table 3. Notes arealso provided at the end of each table, mainly about duplicities. Thecatalogue contains data on 364 CP stars and is updated to 1996, October31. This research has made use of the SIMBAD database, operated at CDS,Strasbourg, France.
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The HR-diagram from HIPPARCOS data. Absolute magnitudes and kinematics of BP - AP stars
The HR-diagram of about 1000 Bp - Ap stars in the solar neighbourhoodhas been constructed using astrometric data from Hipparcos satellite aswell as photometric and radial velocity data. The LM method\cite{luri95,luri96} allows the use of proper motion and radial velocitydata in addition to the trigonometric parallaxes to obtain luminositycalibrations and improved distances estimates. Six types of Bp - Apstars have been examined: He-rich, He-weak, HgMn, Si, Si+ and SrCrEu.Most Bp - Ap stars lie on the main sequence occupying the whole width ofit (about 2 mag), just like normal stars in the same range of spectraltypes. Their kinematic behaviour is typical of thin disk stars youngerthan about 1 Gyr. A few stars found to be high above the galactic planeor to have a high velocity are briefly discussed. Based on data from theESA Hipparcos astrometry satellite and photometric data collected in theGeneva system at ESO, La Silla (Chile) and at Jungfraujoch andGornergrat Observatories (Switzerland). Tables 3 and 4 are onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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High S/N Echelle spectroscopy in young stellar groups. II. Rotational velocities of early-type stars in SCO OB2.
We investigate the rotational velocities of early-type stars in the ScoOB2 association. We measure v.sin(i) for 156 established and probablemembers of the association. The measurements are performed with threedifferent techniques, which are in increasing order of expectedv.sin(i): 1) converting the widths of spectral lines directly tov.sin(i), 2) comparing artificially broadened spectra of low v.sin(i)stars to the target spectrum, 3) comparing the HeI λ4026 lineprofile to theoretical models. The sample is extended with literaturedata for 47 established members of Sco OB2. Analysis of the v.sin(i)distributions shows that there are no significant differences betweenthe subgroups of Sco OB2. We find that members of the binary populationof Sco OB2 on the whole rotate more slowly than the single stars. Inaddition, we find that the B7-B9 single star members rotatesignificantly faster than their B0-B6 counterparts. We test varioushypotheses for the distribution of v.sin(i) in the association. Theresults show that we cannot clearly exclude any form of randomdistribution of the direction and/or magnitude of the intrinsicrotational velocity vector. We also investigate the effects of rotationon colours in the Walraven photometric system. We show that positions ofB7-B9 single dwarfs above the main sequence are a consequence ofrotation. This establishes the influence of rotation on the Walravencolours, due primarily to surface gravity effects.
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Radial velocities and axial rotation for a sample of chemically peculiar stars.
As part of a systematic project we have determined radial velocities andprojected rotational velocities for a sample of 186 chemically peculiarstars which have been observed by the Hipparcos' satellite. The purposeis to provide necessary data to study the space velocities of peculiarstars.
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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.
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A new list of effective temperatures of chemically peculiar stars. II.
Not Available
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Catalogue of Hydrogen Line Spectral Profiles of 236 B-Stars A-Stars and F-Stars
Not Available
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HgMn stars, good or bad for optical soundings in the Milky Way?
Ten mercury-manganese stars from the Michigan Catalogue are examined toassess the consistency of their spectral appearance in sample groupsfrom Galactic optical soundings. The search for classification criteriayields no clear parameters for HgMn stars, and most stars withparticular rotational velocities and temperature ranges exhibit thecharacteristics of HgMn stars. Systematic errors in optical soundingscan be avoided by obtaining samples of stars in the actual temperaturerange used for calibration of absolute magnitude and intrinsic colorsand anticipating a significant fraction of unrevealed HgMn objects.
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The catalogue of equivalent line widths in the spectra of A- and F-stars.
Not Available
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Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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Giant CP stars?
This study is part of an investigation of the possibility of usingchemically peculiar (CP) stars to map local galactic structure. Correctluminosities of these stars are therefore crucial. CP stars aregenerally regarded as main-sequence or near-main-sequence objects.However, some CP stars have been classified as giants. A selection ofstars, classified in the literature as CP giants, are compared to normalstars in the same effective temperature interval and to ordinary'nongiant' CP stars. No clear confirmation of a higher luminosity for'CP giants' than for CP stars in general is found. In addition, CPcharacteristics seem to be individual properties not repeated in acomponent star or other cluster members.
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The surface gravities of AP stars - Spectroscopic estimates from H-beta profiles and comparison with photometry
Observations of 86 Ap stars and 7 normal stars, obtained in H-beta usingthe IDS on the 1.5-m telescope at ESO during March-April 1985 andSeptember 1986, are reported and analyzed. Surface gravities (log g) aredetermined by fitting the spectroscopic data to Kuruczstellar-atmosphere models with 10-times-solar metallicity and some Hedeficiency. These log g values, which depend strongly on the temperaturescale, are then compared with estimates based on uvby-beta or Genevaphotometry in extensive graphs. It is shown that both types ofphotometry give log g in good agreement with spectroscopic values forHgMn stars. For magnetic Ap stars, however, only the log g resultsobtained with uvby-beta photometry agree well with the spectroscopicvalues. No highly evolved Ap stars with log g less than 3 are found.
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Radii and space orientation of the rotational axes of AP stars
The inclination of the rotation axis to the line of sight (i) has beendetermined for a carefully selected sample of Ap stars with reliablevalues of periods of rotation, and values of the stellar radius (R)times sin i have been compared with values of normal main-sequencestars. The findings that none of the obtained R x sin i values aresignificantly larger than the upper limit for the radius of a mainsequence stars and that the mean radius of Ap stars is close to thenormal main sequence value suggest that most Ap stars are main-sequenceobjects. The observed i distribution implies that the distribution ofthe rotational axes of Ap stars in space is random.
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Physical parameters of stars in the Scorpio-Centaurus OB association
Walraven photometry is presented of established and probable members ofthe Scorpio-Centaurus OB association. For each star, effectivetemperature and surface gravity are derived using Kurucz (1979)atmosphere models. From the Straizys and Kuriliene (1981) tables,absolute magnitudes are calculated. Distance moduli and visualextinctions are determined for all stars. From a comparison of theHR-diagrams of the stars in each subgroup with theoretical isochrones,the ages of the three subgroups are derived. The distances to the threesubgroups are shown to be different; there is a general trend (alsowithin each subgroup) for the distances to be larger at higher galacticlongitudes. The visual extinction in the youngest subgroupUpper-Scorpius, is well correlated with the IRAS 100-micron map. Thedistance toward the Ophiuchus dark clouds is found to be 125 pc, basedon the photometric distances to the stars. Most of the early-type starsin Upper-Scorpius are located at the far side of the dark clouds.
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The velocity field of the outer Galaxy in the southern hemisphere. III - Determination of distances to O, B, and A type stars in the Walraven photometric system
The Walraven photometric system has been used to derive distances tostars of spectral types earlier than A7. The details of the observingprocedure are given, and the way the data were analyzed is described.The accuracy of the data is discussed, and the results are compared withthose of Gathier et al. (1986). The observational results for stars ineight well-studied star cluster are presented, compared with theliterature, and discussed.
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First supplement to the catalog of observed periods of AP stars
Supplementary data on the periods of Ap stars with references arepresented; 58 new stars are introduced for which periodic variabilityhas been discovered since 1983. For some of these stars periodicity wasknown before 1983 but they were not reported in the previous catalog.Recently attributed variable star names are also reported.
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Stellar multiplicity in the Scorpius-Centaurus association
Radial velocities are determined for 81 members of the Sco-Cenassociation in order to discover the radial velocity variables. Thefirst orbits are computed for 10 systems, along with improved orbitalelements for another seven systems, using published observations in bothcases. The axial rotation of the association members is used to testwhether both subgroups identified in the association follow the proposedcorrelation between percentage of binaries and axial rotation. Theperiod distribution is studied using all the information available onbinary systems (spectroscopic binaries, visual binaries, and commonproper-motion stars). The total observed multiplicity is derived, and aprobable significant difference in the total multiplicity is foundbetween the two subgroups. An attempt is made to obtain the truemultiplicity using appropriate incompleteness numbers, and somestatistical information about the distribution of the secondary massesis derived. Systems with similar masses seem to be favored regardless oforbital period.
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The evolution of the magnetic fields of AP stars - Magnetic observations of stars in the Scorpius-Centaurus association
Data concerning the positions, photometry, proper motions, and radialvelocities have been compiled for a sample of Ap and Bp stars toward theScorpius-Centaurus association. Probable members of the association areidentified, and new magnetic observations of 13 of these member Ap starsin the mass range 2.5-4.5 solar masses are presented. These magneticobservations are compared with similar data for a sample of old field Apstars. No evidence is found for a significant difference between thedistributions of magnetic field strengths of the two samples, suggestingthat little or no evolution of the magnetic fields in Ap stars occurs ona time scale of a few x 10 to the 8th yr.
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Quantitative Spectral Peculiarity Indices of Cp-Stars of the Upper Main Sequence
Not Available
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Photometric variability of AP and He-weak stars in clusters and associations. II
Periods and lightcurves based on data gathered in the Geneva photometricsystem are given for 19 CP2 and CP4 stars belonging to 11 clusters andassociations. In addition, the lightcurve and approximate period isgiven for HD 22114, a field Ap star recently discovered by means ofGeneva photometry. The strange behavior of the star HD 37151 isconfirmed, althouugh it shows only one stable period. A cosinusoid withits first harmonic is fitted to each lightcurve and the covariancematrix of the errors on the fitted parameters is given, as well as theuncertainty on the period. This work confirms that hot magnetic starsundergo no braking of their axial rotation during their main sequencelifetime and that conservation of angular momentum suffices to explainthe slight increase of period with age.
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Statistical Investigation of Chemically Peculiar Stars - Part Four - Luminosity of Different Type Stars
Not Available
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The 67th Name-List of Variable Stars
Not Available
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Velocities of rotation of chemically peculiar stars
An analysis of the velocities of rotation of 77 peculiar stars, membersof open clusters and associations in the age range log t = 6.4-8.7, wasmade based on observations with the OZSP spectrograph of the 6-mtelescope. It was concluded that there is no loss of angular momentum bypeculiar stars in the process of gravitational contraction as theyapproach the zero-age main sequence and in the stage of evolution withinthe main sequence. A statistically significant difference was obtainedin the velocities of rotation of peculiar stars in different zones ofthe Scorpio-Centaurus association: Stars of the core (t = 4 million yr)rotate faster on the average than stars in the outer zones of theassociation (t = 12 million yr).
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The periods of rotation of the magnetic peculiar stars in the Scorpio-Centaurus association - No evidence of braking on the main-sequence
Photoelectric Stromgren photometry of seven magnetic peculiar stars inUpper Scorpius has been conducted. The periods of photometric variationhave been determined. Periods and periods of magnetic peculiar stars inOrion (North, 1984) are used in a comparison to periods of magneticpeculiar stars in the field. It is concluded that there are nosignificant differences between the periods of the young cluster starsand the periods of the older field stars. This indicates that there isno significant angular momentum loss on the main sequence. Angularmomentum is probably lost before the main sequence.
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The BP and AP stars in the Scorpius-Centaurus moving cluster. II
High-resolution 6-m telescope spectra of ten peculiar stars and fourstars of luminosity class Vb (broad hydrogen lines) in the Sco-Cenmoving cluster provide the degree P and type of peculiarity as well asquantitative spectral types of rotational velocities. Values of theeffective temperature and surface gravity log g are determined for 29peculiar stars in the clusters. Class Vb stars have log g larger by0.2-0.4 than stars on the initial main sequence.
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