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The chemical composition of δ Scuti*
We present chemical abundances in the photosphere of δ Scuti(δ Sct) - a prototype of the class of pulsating variables -determined from the analysis of a spectrum obtained by using the 2-mtelescope at the Peak Terskol Observatory and a high-resolutionspectrometer with R= 52000, a signal-to-noise ratio 250 and fromInternational Ultraviolet Explorer spectra. The abundance pattern ofδ Sct consists of 49 chemical elements. The abundances of 19elements have not been investigated previously. The abundances of Pr andNd obtained from the lines of the second and third spectra are equal.The abundances of heavy elements indicate the overabundances withrespect to the solar system values up to 1 dex. The abundance pattern ofδ Sct is similar to the abundance patterns of Am-Fm or δ Deltype stars.A splitting of the cores of all clean lines is observed for the spectraof δ Sct and HD 57749. This can signify evidence of non-radialpulsations in these stars.
| Spectral disentangling of the triple system DG Leo: orbits and chemical composition
DG Leo is a spectroscopic triple system composed of three stars oflate-A spectral type, one of which was suggested to be a δ Scutistar. Seven nights of observations at high spectral and hightime-resolution at the Observatoire de Haute-Provence with the ELODIEspectrograph were used to obtain the component spectra by applying aFourier transform spectral disentangling technique. Comparing these withsynthetic spectra, the stellar fundamental parameters (effectivetemperature, surface gravity, projected rotation velocity and chemicalcomposition) are derived. The inner binary consists of two Amcomponents, at least one of which is not yet rotating synchronously atthe orbital period though the orbit is a circular one. The distant thirdcomponent is confirmed to be a δ Scuti star with normal chemicalcomposition.
| Observed Orbital Eccentricities
For 391 spectroscopic and visual binaries with known orbital elementsand having B0-F0 IV or V primaries, we collected the derivedeccentricities. As has been found by others, those binaries with periodsof a few days have been circularized. However, those with periods up toabout 1000 or more days show reduced eccentricities that asymptoticallyapproach a mean value of 0.5 for the longest periods. For those binarieswith periods greater than 1000 days their distribution of eccentricitiesis flat from 0 to nearly 1, indicating that in the formation of binariesthere is no preferential eccentricity. The binaries with intermediateperiods (10-100 days) lack highly eccentric orbits.
| The Indo-US Library of Coudé Feed Stellar Spectra
We have obtained spectra for 1273 stars using the 0.9 m coudéfeed telescope at Kitt Peak National Observatory. This telescope feedsthe coudé spectrograph of the 2.1 m telescope. The spectra havebeen obtained with the no. 5 camera of the coudé spectrograph anda Loral 3K×1K CCD. Two gratings have been used to provide spectralcoverage from 3460 to 9464 Å, at a resolution of ~1 Å FWHMand at an original dispersion of 0.44 Å pixel-1. For885 stars we have complete spectra over the entire 3460 to 9464 Åwavelength region (neglecting small gaps of less than 50 Å), andpartial spectral coverage for the remaining stars. The 1273 stars havebeen selected to provide broad coverage of the atmospheric parametersTeff, logg, and [Fe/H], as well as spectral type. The goal ofthe project is to provide a comprehensive library of stellar spectra foruse in the automated classification of stellar and galaxy spectra and ingalaxy population synthesis. In this paper we discuss thecharacteristics of the spectral library, viz., details of theobservations, data reduction procedures, and selection of stars. We alsopresent a few illustrations of the quality and information available inthe spectra. The first version of the complete spectral library is nowpublicly available from the National Optical Astronomy Observatory(NOAO) via ftp and http.
| Tidal Effects in Binaries of Various Periods
We found in the published literature the rotational velocities for 162B0-B9.5, 152 A0-A5, and 86 A6-F0 stars, all of luminosity classes V orIV, that are in spectroscopic or visual binaries with known orbitalelements. The data show that stars in binaries with periods of less thanabout 4 days have synchronized rotational and orbital motions. Stars inbinaries with periods of more than about 500 days have the samerotational velocities as single stars. However, the primaries inbinaries with periods of between 4 and 500 days have substantiallysmaller rotational velocities than single stars, implying that they havelost one-third to two-thirds of their angular momentum, presumablybecause of tidal interactions. The angular momentum losses increase withdecreasing binary separations or periods and increase with increasingage or decreasing mass.
| δ Scuti stars and their related objects
δ Scuti stars are a group of stars located on or a little abovethe main sequence of H-R diagram with spectral type from A3 to F5. Theyare low amplitude single or multi period pulsators with period shorterthan 0.3 d. Within the same area there are several groups of variablesor special stars correlated with them, e.g., Dwarf Cepheids, γ Dorvariables, Blue Stragglers, Am stars, Ap stars, ROAp variables, λBoo variables and δ Del variables. In this paper a general reviewin this field, including the number of new variables discovered after1995, is presented. The most reliable period variation rates for all thehigh amplitude variables and several low amplitude variables are listed.Statistic shows the higher the rotation rate v sin i is, the lower thelight variation amplitude is. Thus within young open clusters highamplitude variables cannot be found. The amplitudes-periods distributionhave 3 peaks with the highest of 1.0 mag in V at 0.17 d in period. Forδ Scuti variables in stellar systems the shorter the averageperiod is, the lower the metallicity and the older the age of thestellar system are.
| 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
| Tidally induced radial-velocity variations in close binaries
A theoretical framework for the determination of tidally inducedradial-velocity variations in a component of a close binary ispresented. Both the free and the forced oscillations of the componentare treated as linear, isentropic perturbations of a sphericallysymmetric star. Resonances between dynamic tides and free oscillationmodes are taken into account by means of the formalism developed by{{Smeyers} et al.} (\cite{SWV1998}). The amplitude of the tidallyinduced radial-velocity variations seen by the observer depends on theorbital eccentricity and on the orbital inclination. The amplitudeincreases with increasing orbital eccentricity and is most sensitive tothe value of the orbital inclination when 20o <~ i <~70o. In the case of a 5 Msun ZAMS star with a 1.4Msun compact companion, it is shown that resonant dynamictides can lead to radial-velocity variations with amplitudes largeenough to be detected in observations. The shape of the tidally inducedradial-velocity curves varies from very irregular for orbital periodsaway from any resonances with free oscillation modes to sinusoidal fororbital periods close to a resonance with a free oscillation mode. Ourinvestigation is concluded with an application to the slowly pulsating Bstar HD 177863 showing the possibility of resonant excitation of ahigh-order second-degree g+-mode in this star.
| Statistics of spectroscopic sub-systems in visual multiple stars
A large sample of visual multiples of spectral types F5-M has beensurveyed for the presence of spectroscopic sub-systems. Some 4200 radialvelocities of 574 components were measured in 1994-2000 with thecorrelation radial velocity meter. A total of 46 new spectroscopicorbits were computed for this sample. Physical relations are establishedfor most of the visual systems and several optical components areidentified as well. The period distribution of sub-systems has a maximumat periods from 2 to 7 days, likely explained by a combination of tidaldissipation with triple-star dynamics. The fraction of spectroscopicsub-systems among the dwarf components of close visual binaries withknown orbits is similar to that of field dwarfs, from 11% to 18% percomponent. Sub-systems are more frequent among the components of widevisual binaries and among wide tertiary components to the known visualor spectroscopic binaries - 20% and 30%, respectively. In triple systemswith both outer (visual) and inner (spectroscopic) orbits known, we findan anti-correlation between the periods of inner sub-systems and theeccentricities of outer orbits which must be related to dynamicalstability constraints. Tables 1, 2, and 6 are 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/382/118
| Resolving Sirius-like binaries with the Hubble Space Telescope
We present initial results from a Hubble Space Telescope ultravioletimaging survey of stars known to have hot white dwarf companions whichare unresolved from the ground. The hot companions, discovered throughtheir EUV or UV emission, are hidden by the overwhelming brightnesses ofthe primary stars at visible wavelengths. Out of 17 targets observed, wehave resolved eight of them with the Wide Field Planetary Camera 2,using various ultraviolet filters. Most of the implied orbital periodsfor the resolved systems are hundreds to thousands of years, but in atleast three cases (56 Persei, ζ Cygni and RE J1925-566) it shouldbe possible to detect the orbital motions within the next few years, andthey may eventually yield new dynamically determined masses for thewhite dwarf components. The 56 Persei and 14 Aurigae systems are foundto be quadruple and quintuple, respectively, including the known opticalcomponents as well as the newly resolved white dwarf companions. Themild barium star ζ Cygni, known to have an 18-year spectroscopicperiod, is marginally resolved. All of these newly resolved Sirius-typebinaries will be useful in determining gravitational redshifts andmasses of the white dwarf components.
| The long-period companions of multiple stars tend to have moderate eccentricities
We examined the statistics of an angle gamma between the radius vectorof a visual companion of a multiple star and the vector of its apparentrelative motion in the system. Its distribution f(gamma ) is related tothe orbital eccentricity distribution in the investigated sample. Wefound that for the wide physical subsystems of the 174 objects from theMultiple Star Catalogue f(gamma ) is bell-shaped. The Monte-Carlosimulations have shown that our f(gamma ) corresponds to the populationof the moderate-eccentricity orbits and is not compatible with thelinear distribution f(e)=2e which follows from stellar dynamics andseems to hold for wide binaries. This points to the absence of highlyelongated orbits among the outer subsystems of multiple stars. Theconstraint of dynamical stability of triple systems is not sufficient toexplain the ``rounded-off'' outer orbits; instead, we speculate that itcan result from the angular momentum exchange in multiple systems duringtheir early evolution.
| 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
| Abundances of C, N, O, and other elements in the atmospheres of the δ Scuti variables 14 Aur, δ Sct, and HD 127986
Using high-resolution spectra, we have determined the abundances ofcarbon (logε(C)), nitrogen (logε(N)), oxygen (logε(O)),silicon (logε(Si)), sulphur (logε(S)), and some other elementsfor three δ Scuti stars. Logε(C) for all three stars andlogε(N) for δ Sct and HD 127986 are close to the solarvalues, while there appears to be a slight (0.15 dex) nitrogendeficiency for 14 Aur. The logε(O) values correspond to a 0.30-dexdeficiency for 14 Aur and δ Sct and a 0.20-dex deficiency for HD127986. The values of logε(Si) for the three stars are close tosolar, and the logε(S) values indicate a slight deficiency (0.10dex) for 14 Aur and HD 127986 and a 0.20-dex excess for δ Sct.Comparison of the elemental abundances for seven δ Scuti starswith those for Am stars shows that the mean deficiencies of C, N, and Oare smaller for pulsating δ Scuti stars than for Am stars withsimilar effective temperatures. The sulphur abundances are virtually thesame for both types of stars.
| Does Rotation Alone Determine Whether an A-Type Star's Spectrum Is Abnormal or Normal?
As noted by Abt & Morrell, virtually all of the metallic line (Am)and peculiar A (Ap) stars have equatorial rotational velocities lessthan 120 km s-1, and most of the normal A0-F0 main-sequencestars have equatorial rotational velocities greater than 120 kms-1. However, at all spectral types there are some (10%-20%)of the normal stars that have smaller rotational velocities. If thisoverlap is real, then a star's rotational velocity is insufficient toexplain its abnormal or normal spectra. We studied the A5-F0 and A2-A4stars and found in both cases that there are stars classified as``normal'' that have unusually weak Ca II K lines and/or that occur inshort-period binaries. Therefore, the overlap seems to be due toundetected marginal abnormal stars. Among the A0-A1 stars we find thatour inability to distinguish consistently the class IV from the class Vstars can explain the overlap because the class IV stars have lowerrotational velocities than class V stars. We conclude from statisticalarguments that rotation alone can explain the appearance of an A star aseither abnormal or normal.
| A revised catalogue of delta Sct stars
An extensive and up-dated list of delta Sct stars is presented here.More than 500 papers, published during the last few years, have beenrevised and 341 new variables have been added to our last list, sixyears ago. This catalogue is intended to be a comprehensive review onthe observational characteristics of all the delta Sct stars known untilnow, including stars contained in earlier catalogues together with othernew discovered variables, covering information published until January2000. In summary, 636 variables, 1149 references and 182 individualnotes are presented in this new list. Tables 1 and 2 will be accessibleonly 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
| Metal abundances of field A and Am stars
Detailed abundances of 9 field A and Am stars are derived for Mg, Ca,Sc, Cr, Fe, and Ni using high resolution spectroscopy. Most of oursample Am stars show the characteristic deficiencies of Ca and Sc on onehand, and the overabundances of the iron peak elements on the other,which is consistent with the predictions of the diffusion model for MainSequence or slightly evolved stars. There seems to be a correlationbetween abundances of Ca and Sc and the effective temperature for starsof similar age: the abundance of Ca increases with increasing masswhereas that of Sc decreases. Two of our Am stars have a differentabundance pattern: Ca is overabundant in the hot magnetic Am star o Pegand its abundance is nearly normal in the metallic giant star rho Pup.The other objects of our sample have globally a solar composition except28 And, which shows significant deficiencies for most the studiedelements. Based on observations collected at the Observatoire deHaute-Provence (France), and on data from the ESA\protect\linebreakHIPPARCOS astrometry satellite.
| The effect of diffusion on pulsations of stars on the upper main sequence --- δ Scuti and metallic A stars
Recent dramatic improvements in the modeling of abundance evolution dueto diffusion in A stars have been achieved with the help ofmonochromatic opacity tables from the OPAL group. An important result inthe context of stellar pulsations is the substantial helium abundanceshown to be left over in the driving region of δ Scuti-typepulsations in chemically peculiar Am stars. An accurate opacity profilein the entire stellar envelope including the full effect of heavyelements is also now available for the first time. Pulsations are shownto be excluded for young Am stars but occur naturally when these starsevolve off the ZAMS. The predicted variable metallic A stars all lietowards the red edge of the instability strip, in qualitative agreementwith the observed variable δ Delphini and mild Am stars. Resultsshow little direct excitation from iron-peak elements in A-type stars.The main abundance effect is due to the settling of helium, along with amarginal effect due to the enhancement of hydrogen.
| A search for hidden white dwarfs in theROSATEUV survey - II. Discovery of a distant DA+F6/7V binary system in a direction of low-density neutral hydrogen
The ROSAT Wide Field Camera (WFC) survey of the extreme ultraviolet(EUV) has provided us with evidence for the existence of a previouslyunidentified sample of hot white dwarfs in unresolved, detached binarysystems. These stars are invisible at optical wavelengths due to theclose proximity of their much more luminous companions (spectral type Kor earlier). However, for companions of spectral type ~A5 or later thewhite dwarfs are easily visible at far-ultraviolet wavelengths, and canbe identified in spectra taken by IUE. 16 such systems have beendiscovered in this way through ROSATEUVEIUE observations, including fouridentified by us in Paper I. In the present paper we report the resultsof our continuing search during the final year of IUE operations. Onenew system, RE J0500-364 (DA+F6/7V), has been identified. This starappears to lie at a distance of ~500-1000 pc, making it one of the mostdistant white dwarfs, if not the most distant, to be detected in the EUVsurveys. The very low line-of-sight neutral hydrogen volume density tothis object could place a lower limit on the length of the beta CMainterstellar tunnel of diffuse gas, which stretches away from the LocalBubble in a similar direction to RE J0500-364. In this paper we alsoanalyse a number of the stars observed where no white dwarf companionwas found. Some of these objects show evidence for chromospheric andcoronal activity. Finally, we present an analysis of the previouslyknown WD+active F6V binary HD 27483 (Bohm-Vitense 1993), and show that,at T~22000K, the white dwarf may be contributing significantly to theobserved EUV flux. If so, it is one of the coolest such stars to bedetected in the EUV surveys.
| A common resonance of delta SCT stars and ellipsoidal binaries.
Not Available
| Hot White Dwarfs in the Extreme-Ultraviolet Explorer Survey. IV. DA White Dwarfs with Bright Companions
We present an analysis of optical, ultraviolet, and X-ray spectralproperties of a sample of 13 hot hydrogen-rich (DA) white dwarfs, eachpaired with a luminous unresolved companion. Using low-dispersionInternational Ultraviolet Explorer spectra, ROSAT photometry, andExtreme-Ultraviolet Explorer photometry and spectroscopy, we estimatethe effective temperature, mass, and distance of the white dwarfs.Additionally, we examine the question of their atmospheric composition.We establish orbital properties for most binaries by means ofhigh-dispersion optical spectroscopy obtained with the Hamilton echellespectrograph at Lick Observatory; the same data help uncover evidence ofactivity in some of the secondary stars that is also notable in ROSATX-ray measurements. In particular, we find high-amplitude (>20 kms-1) velocity variations in only two stars (HD 33959C and HR 8210),low-amplitude variations in four additional objects (HD 18131, HR 1608,theta Hya, and BD +27 deg1888), and no variations (<2 km s-1) in theremainder. We have observed Ca H and K in emission in four (BD +08deg102, HD 18131, HR 1608, and EUVE J0702+129) of the six objects thatwere also detected in the 0.52-2.01 keV ROSAT PSPC band, while thesource of the hard X-ray emission in HD 33959C remains unknown; otherinvestigators have noted some evidence of activity in the remaining0.52-2.01 keV detection, HD 217411. Properties of the white dwarfs arealso investigated; EUV spectroscopy shows the effect of a low heavyelement abundance in the atmosphere of the white dwarf in HD 33959C andof a high heavy element abundance in HD 223816; measurements of allother objects are apparently consistent with emission from pure-hydrogenatmospheres. However, current data do not constrain well the white dwarfparameters, and, to remedy the situation, we propose to obtainspectroscopy of the complete H Lyman line series.
| 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 rotation of ellipsoidal binary systems.
Not Available
| 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
| MSC - a catalogue of physical multiple stars
The MSC catalogue contains data on 612 physical multiple stars ofmultiplicity 3 to 7 which are hierarchical with few exceptions. Orbitalperiods, angular separations and mass ratios are estimated for eachsub-system. Orbital elements are given when available. The catalogue canbe accessed through CDS (Strasbourg). Half of the systems are within 100pc from the Sun. The comparison of the periods of close and widesub-systems reveals that there is no preferred period ratio and allpossible combinations of periods are found. The distribution of thelogarithms of short periods is bimodal, probably due to observationalselection. In 82\% of triple stars the close sub-system is related tothe primary of a wide pair. However, the analysis of mass ratiodistribution gives some support to the idea that component masses areindependently selected from the Salpeter mass function. Orbits of wideand close sub-systems are not always coplanar, although thecorresponding orbital angular momentum vectors do show a weak tendencyof alignment. Some observational programs based on the MSC aresuggested. Tables 2 and 3 are 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/Abstract.html
| Spectroscopic survey of delta Scuti stars. I. Rotation velocities and effective temperatures
Projected rotational velocities and effective temperatures for 68 deltaSct stars as well as 41 non-variable stars of similar spectral type andluminosity are presented here. The rotational velocities have beencalculated following the method developed in \cite[Gray (1992)]{ref38}and effective temperatures have been derived using the Balmer lineprofiles. The temperatures obtained from this method are shown to be inreasonable agreement with those calculated using the Infrared FluxMethod (IRFM) or spectrophotometric methods. This result has allowed usto use our temperatures to compare different uvby beta photometriccalibrations. We find that the calibration given by \cite[Moon \&Dworetsky (1985)]{ref72} is the most consistent. In the second part ofthis paper we have studied the relation between the pulsationalproperties (periods and amplitudes) and the physical parameters (v sin iand Teff). Where pulsation modes have been determined, thelow amplitude $\delta$ Scutis tend to be multimode (radial andnon-radial) pulsators, consistent with the theory that non-linearcoupling between modes acts to limit the amplitude in these stars. Wehave compared the distribution of v sin i for low amplitude $\delta$Scutis and non-variable stars. This shows the $\delta$ Scutis have abroader distribution in v sin i suggesting that a high rotation velocitymay favour pulsation. We find that the large amplitude delta Scuti starstend to have longer periods, cooler temperatures and lower rotationvelocities. Given that the large amplitude stars are also relativelyrare all the above are consistent with the hypothesis that these starsare more evolved (sub-giants) than the low amplitude delta Scutis (mainsequence or early post-main sequence).
| Orbits of new spectroscopic components in 7 multiple systems
New close sub-systems are discovered in wide physical multiple stars.Elements of spectroscopic orbits are given for the components ofquadruple systems ADS 1315C, 3608C, 3824C, 3991A and for the componentsof triple systems ADS 1849A, 6646A, 8861A. Physical parameters(magnitudes, spectral types, masses of individual components, distancesto the systems, angular separations) are estimated by combining allavailable data. The nearby M dwarf ADS 8861A = Gliese 507A is a goodcandidate for speckle resolution. The very hot white dwarf discovered by[Hodgkin et al. (1993)]{ref12} is likely to be an additional visualcomponent to ADS 3824C, so this system may be quintuple; however, asearch of 2fd 993 photometric periodicity possibly caused by the hotclose companion is highly desirable. Table 4 and Appendix are onlyavailable in electronic form at the CDS via anonymous ftp to:cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Luminosity and related parameters of δ Scuti stars from HIPPARCOS parallaxes. General properties of luminosity.
The absolute magnitudes of δ Scuti stars derived from parallaxesmeasured by the Hipparcos astrometric satellite are discussed andcompared with the previous estimates based on photometric uvbyβindices. There are significant differences which are related tophotometric effects of metallicity and rotational velocity, but thepossible effect of a close companion on the measured apparent magnitudeshould be also taken into account. The possibility of differentgroupings of δ Scuti stars based on the absolute magnitudes isbriefly discussed. Some high amplitude δ Scuti stars withintermediate or normal metallicity and small and uncertain parallax haveapparently a very low luminosity; this could be a systematic effectrelated to the observational errors.
| A Catalogue of Correlations Between Eclipsing Binaries and Other Categories of Double Stars
Among the 9110 stars in The Bright Star Catalogue, there are 225eclipsing or ellipsoidal variables. A search has been made for these incatalogues of spectroscopic binaries, visual double or multiple stars,speckle interferometry, occulation binaries, and galatic clusters. Themajority of the photometric binaries are also members of groups ofhigher multiplicity. The variables are in systems ranging from one to 91stars, five on the average. 199 are either spectroscopic binaries (SB)or stars with variable radial velocity, with orbital periods known for160. Photometric periods are lacking for 48 while SB periods areavailable for 23 of these. Observers with photoelectric equipment areencouraged to plan observations to test if the SB periods are consistentwith photometric data. Observers are likewise encouraged to examinethose stars for which the photometric and SB periods appear to beinconsistent. Parallaxes are available for 86 of the stars, 41 of themindicating distances nearer than 50 parsecs.
| 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
| 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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