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Rotational velocities of A-type stars. IV. Evolution of rotational velocities
Context. In previous works of this series, we have shown that late B-and early A-type stars have genuine bimodal distributions of rotationalvelocities and that late A-type stars lack slow rotators. Thedistributions of the surface angular velocity ratio?/?crit (?crit is the criticalangular velocity) have peculiar shapes according to spectral typegroups, which can be caused by evolutionary properties. Aims: Weaim to review the properties of these rotational velocity distributionsin some detail as a function of stellar mass and age. Methods: Wehave gathered vsini for a sample of 2014 B6- to F2-type stars. We havedetermined the masses and ages for these objects with stellar evolutionmodels. The (Teff,log L/L&sun;)-parameters weredetermined from the uvby-? photometry and the HIPPARCOS parallaxes. Results: The velocity distributions show two regimes that dependon the stellar mass. Stars less massive than 2.5 M&sun; havea unimodal equatorial velocity distribution and show a monotonicalacceleration with age on the main sequence (MS). Stars more massive havea bimodal equatorial velocity distribution. Contrarily to theoreticalpredictions, the equatorial velocities of stars from about 1.7M&sun; to 3.2 M&sun; undergo a strong accelerationin the first third of the MS evolutionary phase, while in the last thirdof the MS they evolve roughly as if there were no angular momentumredistribution in the external stellar layers. The studied stars mightstart in the ZAMS not necessarily as rigid rotators, but with a totalangular momentum lower than the critical one of rigid rotators. Thestars seem to evolve as differential rotators all the way of their MSlife span and the variation of the observed rotational velocitiesproceeds with characteristic time scales ?t ? 0.2tMS, where tMS is the time spent by a star in theMS.Full Table 1 is only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A120Appendicesare available in electronic form at http://www.aanda.org
| A Volume-limited Photometric Survey of 114 ? Doradus Candidates
We have carried out a photometric survey of a complete, volume-limitedsample of ? Doradus candidates. The sample was extracted from theHipparcos catalog and consists of 114 stars with colors and absolutemagnitudes within the range of known ? Doradus stars and that alsolie within a specified volume of 266,600 pc3. We devoted oneyear of observing time with our T12 0.8 m automatic photometrictelescope to acquire nightly observations of the complete sample ofstars. From these survey observations, we identify 37 stars withintrinsic variability of 0.002 mag or more. Of these 37 variables, 8have already been confirmed as ? Doradus stars in our earlierpapers; we scheduled the remaining 29 variables on our T3 0.4 mautomatic telescope to acquire more intensive observations over the nexttwo years. As promising new ? Doradus candidates were identifiedfrom the photometry, we obtained complementary spectroscopicobservations of each candidate with the Kitt Peak coudé feedtelescope. Analysis of our new photometric and spectroscopic datareveals 15 new ? Doradus variables (and confirms two others), 8new ? Scuti variables (and confirms one other), and 3 newvariables with unresolved periodicity. Therefore, of the 114 ?Doradus candidates in our volume-limited sample, we find 25 stars thatare new or previously known ? Doradus variables. This results inan incidence of 22% for ? Doradus variability among candidatefield stars for this volume of the solar neighborhood. The correspondingspace density of ? Doradus stars in this volume of space is 0.094stars per 103 pc3 or 94 stars per 106pc3. We provide an updated list of 86 bright, confirmed,? Doradus field stars.
| Random forest automated supervised classification of Hipparcos periodic variable stars
We present an evaluation of the performance of an automatedclassification of the Hipparcos periodic variable stars into 26 types.The sub-sample with the most reliable variability types available in theliterature is used to train supervised algorithms to characterize thetype dependencies on a number of attributes. The most useful attributesevaluated with the random forest methodology include, in decreasingorder of importance, the period, the amplitude, the V-I colour index,the absolute magnitude, the residual around the folded light-curvemodel, the magnitude distribution skewness and the amplitude of thesecond harmonic of the Fourier series model relative to that of thefundamental frequency. Random forests and a multi-stage scheme involvingBayesian network and Gaussian mixture methods lead to statisticallyequivalent results. In standard 10-fold cross-validation (CV)experiments, the rate of correct classification is between 90 and 100per cent, depending on the variability type. The main mis-classificationcases, up to a rate of about 10 per cent, arise due to confusion betweenSPB and ACV blue variables and between eclipsing binaries, ellipsoidalvariables and other variability types. Our training set and thepredicted types for the other Hipparcos periodic stars are availableonline.
| Long-term photometric monitoring with the Mercator telescope. Frequencies and multicolour amplitudes of γ Doradus stars
Context: γ Dor stars are excellent targets for asteroseismologysince the gravity modes present in these stars probe the deep stellarinteriors. Mode identification will improve the knowledge of these starsconsiderably. Aims: A selected group of γ Dor stars and somecandidates were observed with the Mercator telescope to find and/orconfirm the periodicities in the light variations and to derive reliableamplitude ratios in different pass bands. Methods: A frequency analysiswas performed on all new data obtained in the Geneva photometric system.In order to have more reliable and accurate frequencies, the new datawere combined with similar data from the literature and with Hipparcosobservations. A set of frequencies that minimized the residuals in aharmonic fit was searched for while allowing means and amplitudes tovary from one observation set to another. Results: Frequencies andamplitudes in the photometric passbands of the Geneva system are givenfor 21 γ Dor stars. We report the discovery of HD74504 as a newly found γ Dor star. Conclusions: Ourstudy provides the first extensive multicolour database for theunderstanding of gravity modes in F-type stars.Based on observations collected with the Flemish 1.2-m MercatorTelescope at Roque de los Muchachos, La Palma. Tables 5 to 25 are alsoavailable 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/499/967
| Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo
We present measurements of chromospheric Ca ii H&K activity for 481solar-like stars. To determine the activity we used the Mount Wilsonmethod and a newly developed method which allows to also measure Ca iiH&K emission features in very rapidly rotating stars. The newtechnique determines the activity by comparing the line shapes fromknown inactive slowly rotating template stars that have beenartificially broadened to spectra of rapid rotators. We have analyzedsolar-like stars ranging from T_eff = 5000 to 7800 K with rotationalvelocities up to 190 km s-1 in our sample of FOCES and FEROSspectra. The effects of the rotational broadening on the two methodshave been quantified. Our method has proven to produce consistentresults where S-Index values are available and offers the possibility tomeasure the chromospheric activity at the onset of the solar-likedynamo.Table 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/493/1099
| A catalogue of multiplicity among bright stellar systems
We consider the multiplicity of stellar systems with (combined)magnitude brighter than 6.00 in Hipparcos magnitudes. We identify 4559such bright systems (including the Sun), and the frequencies ofmultiplicities 1, 2,..., 7 are found to be 2718, 1437, 285, 86, 20, 11and 2. We discuss the uncertainties, which are substantial. We alsoconsider the distributions of periods of orbits and suborbits. We notethat for even more restricted set of 478 systems with VH<= 4.00, the proportions of higher multiples up to sextuple areprogressively larger (213, 179, 54, 19, 8, 5), suggesting substantialincompleteness in even the reasonably well studied larger sample.This sample can be seen as relatively thoroughly studied formultiplicity, and reasonably representative of stars more massive thanthe Sun. But the restriction to VH <= 6 means that oursample contains hardly any systems where all components are low-massmain-sequence stars (K or M).Data on multiplicity are important as a constraint on (i) the starformation problem, (ii) the problem of the evolution of the Galacticstellar population and (iii) the interaction of dynamics and evolutionthrough the effect of Kozai cycles. We discuss these topics briefly.
| Broadband imaging and narrowband polarimetry of comet 73P/Schwassmann-Wachmann 3, components B and C, on 3, 4, 8, and 9 May 2006
Context: The Jupiter family comet 73P/Schwassmann-Wachmann 3 (SW3) splitinto several pieces in 1995. Some of the original fragments wereobserved during the next apparition of the comet in 1999-2001. The lastreturn of the comet in 2005-2006 was accompanied by tremendous furthersplitting of some SW3 components - in particular component B - into alarge number of subfragments. Aims: We present observations ofcomponents B and C during their closest approach to Earth in the firsthalf of May 2006. These results aim at characterizing the properties ofdust particles released from the fragments of comet SW3 and atidentifying dusty and gaseous structures in the comae and tail regionsof components B and C, which could be useful for conclusions about thepresence of active regions and break-up events of the components. Methods: We used narrowband imaging polarimetry and an analysis of thebroadband surface brightness for the characterization of the dust comaeof the SW3 components. Coma and tail structures in components B and Cwere enhanced by numerical methods. Results: The degree of linearpolarization of components B and C follows the empirical phase-angledependence as derived from other comets. Fragment B was found inoutburst on May 8. The brightness outburst was accompanied by changes inthe shape of the coma. During the outburst, the spatial distribution ofthe linear polarization showed some peculiarities that had disappearedagain on May 9. Arc-like signatures of a temporary nature, typical offragmentation events, are seen in broadband filter images of component Bon 3, 8, and 9 May 2006. The secondary dust tail, seen in component B on3 and 4 May 2006, marks the synchrone of an earlier splitting eventaround 25 April 2006. Fan-like coma structures are found in the sunwardcoma hemisphere of components B and C that might be related to localizedenhanced activity on the rotating nuclei.Based on observations performed at the National AstronomicalObservatory, Rozhen, Bulgaria.
| UV flux distributions of γ Doradus stars
Context: It seems that the recently identified class of pulsating stars,the γ Dor type-variables, includes objects with different metalabundances and a large percentage of binaries. Aims: We looked forindicators of metal abundance peculiarities and stellar binarity in asample of 40 confirmed γ Dor stars. Methods: Absolute magnitudesfrom Hipparcos parallaxes and UV magnitudes, from the S2/S68 experimenton board the TD1 satellite, are retrieved from databases and comparedwith predicted values. A set of non variable normal stars is used tocheck the consistency of this analysis and also serve as referencestars. Results: Twenty-nine stars of the γ Dor star sample,which is 73% of it, are discovered having abnormal UV fluxes constantlyshowing UV flux excesses compared to those computed with the atmosphericparameters (Teff , log g, and metallicity) determined fromcalibration of the uvbyβ indices. The reason for this UV excess offlux at 196.5 nm and at 236.5 nm, which was previously known only for HD209295, cannot be ascribed to binarity alone. An extra source of UV fluxor less UV absorption - yet unknown - must be present.Tables 1-3 are only 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/472/241
| Photometry and Spectroscopy of 11 γ Doradus Stars
We have used precise photometric and high-dispersion spectroscopicobservations to study 11 γ Doradus stars, 10 of them newlyconfirmed. Only five of these 11 γ Doradus stars appear to besingle; two are primaries of double-lined spectroscopic binaries, one isthe secondary of a double-lined binary, two are primaries of visualbinaries and, in the case of the double-lined binary (HD 86371), eitheror both components could be a pulsating γ Doradus star. We havedetermined a preliminary orbital period of 5.32 days for thedouble-lined binary HD 41547. Several of the stars show spectroscopicline-profile and low-amplitude radial velocity variability indicative ofpulsation. All 11 stars are photometrically variable with amplitudesbetween 4 and 94 mmag in Johnson B and periods between 0.38 and 1.86days. The 11 stars have between two and five independent periods. Thevariability at all periods approximates a sinusoid. We provide a newtabulation of all 66 γ Doradus stars confirmed to date and listsome of their properties. All are dwarfs or subgiants and lie within awell-defined region of the H-R diagram that overlaps the cool edge ofthe δ Scuti instability strip. Four of the new γ Doradusvariables from this paper also lie within the δ Scuti instabilitystrip but do not exhibit the additional higher frequency variabilitytypical of δ Scuti stars. Among the 66 confirmed γ Doradusvariables, we find no correlation between the period of the strongestpulsation mode and the (B-V) color index, absolute magnitude, orluminosity.
| Rotational velocities of A-type stars. III. Velocity distributions
Aims.A sample of v sin i of B9 to F2-type main sequence single stars hasbeen built from highly homogeneous {v sin i} parameters determined for alarge sample cleansed of objects presenting the Am and Ap phenomenon aswell as of all known binaries. The aim is to study the distributions ofrotational velocities in the mass range of A-type stars for normalsingle objects. Methods: .Robust statistical methods are used torectify the {v sin i} distributions for the projection effect and theerror distribution. The equatorial velocity distributions are obtainedfor about 1100 stars divided in six groups defined by the spectral type,under the assumption of randomly orientated rotational axes.Results: .We show that late B and early A-type main-sequence stars havegenuine bimodal distributions of true equatorial rotational velocitiesprobably due to angular momentum loss and redistribution that the starunderwent before reaching the main sequence. A striking lack of slowrotators is noticed among intermediate and late A-type stars.Full Table [see full text] is 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/cgi-bin/qcat?J/A+A/463/671 Appendices areonly available in electronic form at http://www.aanda.org
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Non-radial pulsations in the γ Doradus star HD 195068
We present high resolution spectroscopic observations of the γDoradus star HD 195068. About 230 spectra werecollected over 2 years. Time series analysis performed on radialvelocity data shows a main peak at 1.61 d-1 , a frequency notyet detected in photometry. The Hipparcos photometric 1.25d-1 frequency is easily recovered as is 1.30 d-1while the third photometric frequency, 0.97 d-1 , is onlymarginally present. The good quality of our data, which includes 196spectra collected over seven consecutive nights, shows that both the1.61 d-1 and intermediate 1.27 d-1 (mixture of1.25 and 1.30 d-1 ) frequencies are present in the lineprofile variations. Using the Fourier-Doppler Imaging (FDI) method, thevariability associated with 1.61 d-1 can be successfullymodeled by a non-radial pulsation mode ℓ=5± 1, |m|=4±1. For the intermediate frequency 1.27 d-1 we deduceℓ=4± 1, |m|=3± 1. Evidence that the star is notpulsating in the radial mode (ℓ=0) rules out a previousclassification as an RR Lyrae type star. We investigate the timevariability of FDI power spectra concluding that the observed temporalvariability of modes can be explained by a beating phenomenon betweenclosely spaced frequencies of two non-radial modes. The distribution ofthe oscillation power within the line profile indicates that there is asignificant tangential velocity component of oscillations characteristicof high radial order gravity modes which are predicted to be observed inγ Doradus type stars.
| Fourier-Doppler imaging of non-radial pulsations in gamma Doradus stars .
This paper deals with a class of non-radial pulsators along the mainsequence, namely the gamma Doradus stars for which much effort iscurrently made in order to constrain their pulsation characteristics.However, because of their relatively low amplitude (few tens of mmag inphotometry) and due to the long time scales of the variation (between0.3 and 3 days), the detection and identification of their pulsations israther difficult, using the photometric data only. Consequently, thespectroscopic studies of the stars having well-known photometricproperties are very valuable and we study in detail the line profilevariability (LPV) in gamma Doradus candidates observed at Observatoirede Haute-Provence during a two-year high-resolution spectroscopycampaign. The non-radial behavior of selected stars is revealed with theadvent of Doppler Mapping and two-dimensional Fourier-Doppler Imagingmethods for line-profile analysis, which allowed us to detect andidentify the pulsation modes described below.
| Proper identification of RR Lyrae stars brighter than 12.5 mag
RR Lyrae stars are of great importance for investigations of Galacticstructure. However, a complete compendium of all RR-Lyraes in the solarneighbourhood with accurate classifications and coordinates does notexist to this day. Here we present a catalogue of 561 local RR-Lyraestars (V_max ≤ 12.5 mag) according to the magnitudes given in theCombined General Catalogue of Variable Stars (GCVS) and 16 fainter ones.The Tycho2 catalogue contains ≃100 RR Lyr stars. However, manyobjects have inaccurate coordinates in the GCVS, the primary source ofvariable star information, so that a reliable cross-identification isdifficult. We identified RR Lyrae from both catalogues based on anintensive literature search. In dubious cases we carried out photometryof fields to identify the variable. Mennessier & Colome (2002,A&A, 390, 173) have published a paper with Tyc2-GCVSidentifications, but we found that many of their identifications arewrong.
| Eleven New γ Doradus Stars
We present new high-dispersion spectroscopic and precise photometricobservations to identify 11 new γ Doradus variables. Seven ofthese new γ Doradus stars appear to be single, three are primariesof single-lined binaries, and one has two distant visual companions;none are double-lined or close visual binaries. Several of the starsshow spectroscopic line-profile and low-amplitude radial velocityvariability indicative of pulsation. All 11 stars are photometricallyvariable with amplitudes between 8 and 93 mmag in Johnson B and periodsbetween 0.398 and 2.454 days. One star is monoperiodic; the rest havebetween two and five independent periods. The variability at all periodsapproximates a sinusoid, although three of the stars exhibitcycle-to-cycle variation in the level of maximum brightness, similar tothe Blazhko effect observed in some RR Lyrae stars. We provide a newtabulation of all 54 γ Doradus stars confirmed to date and listsome of their properties. All are dwarfs or subgiants and lie within awell-defined region of the H-R diagram that overlaps the cool edge ofthe δ Scuti instability strip. Four of the new γ Doradusvariables from this paper also lie within the δ Scuti instabilitystrip but do not exhibit the additional higher frequency variabilitytypical of δ Scuti stars. The variability type of several of thesestars given in the General Catalog of Variable Stars and in SIMBADshould now be revised.
| Multi-site, multi-technique survey of γ Doradus candidates. I. Spectroscopic results for 59 stars
We present the first results of a 2-year high-resolution spectroscopycampaign of 59 candidate γ Doradus stars which were mainlydiscovered from the HIPPARCOS astrometric mission. More than 60% of thestars present line profile variations which can be interpreted as due topulsation related to γ Doradus stars. For all stars we alsoderived the projected rotation velocity (up to more than 200 kms-1). The amplitude ratios 2K/Δ m for the mainHIPPARCOS frequency are in the range 35-96 kms-1,mag-1. About 50% of the candidates arepossible members of binary systems, with 20 stars being confirmedγ Doradus. At least 6 stars present composite spectra, and in allbut one case (for which only one spectrum could be obtained), the narrowcomponent shows line profile variations, pointing towards anuncomfortable situation if this narrow component originates from a shellsurrounding the star. This paper is the first of a series concerningmode identification using both photometric and spectroscopic methods forthe confirmed γ Doradus stars of the present sample.Partially based on observations obtained at the Observatoire deHaute-Provence.
| Spectroscopy of Early F Stars: γ Doradus Candidates and Possible Metallic Shell Stars
We obtained high-resolution spectroscopic observations of 34 γDoradus candidates. From the red-wavelength spectra, we determinedspectral classes, radial velocities, and projected rotationalvelocities. The spectra of seven late A or early F stars show metalliclines that have composite profiles consisting of a narrow component nearthe center of a broad line, indicating that they may be shell stars orbinaries. Several stars, including HD 152896, HD 173977, HD 175337, andHD 195068/9, show large line profile asymmetries. Two stars, HD 11443(=α Trianguli) and HD 149420, are ellipsoidal variables and notγ Doradus stars. The percentage of binary systems in our samplemay be as high as 74%.
| Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
| The domain of γ Doradus variables in the Hertzsprung-Russell diagram
70 new γ Doradus candidates were identified from Hipparcosphotometry, which represents more than a doubling of the presently knownnumber. Selecting the objects with good evidence for multiperiodicity,it is found that these stars, together with bona fide members of theclass, occupy a well-defined region in a colour-magnitude diagram. Thisdomain corresponds to a range of 7200-7700K on the zero-age mainsequence (ZAMS) and 6900-7500K one magnitude above it, which partlyoverlaps with the instability strip of δ Scuti stars. For thefirst time, γ Doradus stars can be discussed as a group. They canbe found over a significant fraction of the main sequence lifetimes forobjects in the relevant temperature range. An upper limit on the surfacemetallicity of γ Doradus stars is apparent, which may guide thesearch for their pulsation driving mechanism. The importance of possibleobjects exhibiting both γ Doradus and δ Scuti-typepulsations is discussed.
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| The ROSAT all-sky survey catalogue of optically bright main-sequence stars and subgiant stars
We present X-ray data for all main-sequence and subgiant stars ofspectral types A, F, G, and K and luminosity classes IV and V listed inthe Bright Star Catalogue that have been detected as X-ray sources inthe ROSAT all-sky survey; several stars without luminosity class arealso included. The catalogue contains 980 entries yielding an averagedetection rate of 32 percent. In addition to count rates, sourcedetection parameters, hardness ratios, and X-ray fluxes we also listX-ray luminosities derived from Hipparcos parallaxes. The catalogue isalso available in electronic form via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| On the use of the HIPPARCOS intermediate astrometric data
With the publication of the Hipparcos catalogue, astrometric data ofunprecedented quality and quantity has become available, providingparallaxes, positions and proper motions free from systematic errorsdown to a level of at least 0.1 mas and 0.1 mas y(-1) . The Hipparcoscatalogue, however, contains not only these ``ready-to-use'' positions,parallaxes and proper motions, but also intermediate astrometric data orabscissa residuals, which are the data from which the astrometricsolutions were obtained. These data allow alternative solutions to bemade for the astrometric parameters, for example, through the use ofadditional information. When combining data from stars in a small areaon the sky, it becomes possible to account for correlations that existbetween the abscissa residuals for stars measured on the same greatcircle. This is relevant for stars in open clusters and the MagellanicClouds, where such correlations will be very frequent. The intermediatedata also provide the possibility to add external constraints to anastrometric solution, such as an approximate but small parallax value,one that would have been too small to measure with Hipparcos. In thatcase the parallax can be fixed at the estimated small value, giving abetter constrained solution for the proper motion. Similarly, when for agroup of stars the absolute magnitudes are linked through aperiod-luminosity relation or by being all closely the same, as for RRLyrae stars, such a condition can be superimposed on the parallaxsolution for all stars in this group, providing a distance scalecalibration well beyond the range of direct parallax measurements. Anexample of how to use the data for solar system objects, which areprovided only in the form of intermediate astrometric data, is shown.Based on observations made with the ESA Hipparcos satellite. Table 2 inits entirety is available at the CDS via anonymous ftp 130.79.128.5 orvia http://cdsweb.u-strasbg.fr/Abstract.html
| Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The photoelectric astrolabe catalogue of Yunnan Observatory (YPAC).
The positions of 53 FK5, 70 FK5 Extension and 486 GC stars are given forthe equator and equinox J2000.0 and for the mean observation epoch ofeach star. They are determined with the photoelectric astrolabe ofYunnan Observatory. The internal mean errors in right ascension anddeclination are +/- 0.046" and +/- 0.059", respectively. The meanobservation epoch is 1989.51.
| 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.
| The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..135A&db_key=AST
| The general catalogue of trigonometric [stellar] paralaxes
Not Available
| Optical Polarization of 1000 Stars Within 50-PARSECS from the Sun
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..101..551L&db_key=AST
| The Differential Extinction Toward Nova Cygni 1992
Not Available
| Third preliminary catalogue of stars observed with the photoelectric astrolabe of the Beijing Astronomical Observatory.
Not Available
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Observation and Astrometry data
| Constellation: | Schwan |
| Right ascension: | 20h27m02.27s |
| Declination: | +49°23'00.1" |
| Apparent magnitude: | 5.722 |
| Proper motion RA: | 66.3 |
| Proper motion Dec: | 57.8 |
| B-T magnitude: | 6.087 |
| V-T magnitude: | 5.753 |
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