NEWS@SKY (Science&Space News)
Home     To Survive in the Universe
 .MYA{ color: yellow; text-decoration: none; :hover { color: red; text-decoration: none; } } Services
Why to Inhabit     Top Contributors     Astro Photo     The Collection     Forum     Blog New!     FAQ     Login

ι Car (Aspidiske)

Contents

Images

DSS Images   Other Images

Related articles

 CNO in evolved intermediate mass starsIn order to investigate the possible influence of rotation on theefficiency of the first dredge-up we determined atmospheric parameters,masses, and abundances of carbon, nitrogen, and oxygen in a sample ofevolved intermediate mass stars. We used high resolution spectra andconducted a model atmosphere analysis. The abundances were calculatedthrough spectral synthesis and compared to the predictions of rotatingand non-rotating evolutionary models. Almost all those objects in oursample where carbon and nitrogen abundances could be determined showsigns of internal mixing. The stars, however, seem to be mixed todifferent extents. Among the mixed stars we identify five in our samplewith abundances in agreement with the non-rotating models, four starsthat seem to be mixed beyond that, and one star that seems to beslightly less mixed than predicted for the first dredge-up. There arealso five stars that seem to be slightly more mixed than expected, buttheir abundances are in marginal agreement with both rotating andnon-rotating models. Such differences in the extent of the mixing arenot predicted by the standard models and imply the action of othermixing mechanisms than solely the convective dredge-up. We alsoidentified for the first time an important correlation between the [N/C]ratio and the stellar mass. Atlas and Catalog of Dark Clouds Based on Digitized Sky Survey IWe present a quantitative atlas and catalog of dark clouds derived byusing the optical database Digitized Sky Survey I''. Applying atraditional star-count technique to 1043 plates contained in thedatabase, we produced an AV map covering the entire region inthe galactic latitude range |b| ≤ 40°. The map was drawn at twodifferent angular resolutions of 6' and 18', and is shown in detail in aseries of figures in this paper. Based on the AV map, weidentified 2448 dark clouds and 2841 clumps located inside them. Somephysical parameters, such as the position, extent, and opticalextinction, were measured for each of the clouds and clumps. We alsosearched for counterparts among already known dark clouds in theliterature. The catalog of dark clouds presented in this paper lists thecloud parameters as well as the counterparts. A spectroscopic study of bright southern Cepheids - a high-resolution view of Cepheid atmospheresWe present high-resolution spectroscopic observations andspecies-by-species radial velocities of a number of southern Cepheids.The stars (BP Cir, V350 Sgr, AX Cir, V636 Sco, W Sgr, S Mus, β Dor,TT Aql, Y Oph, YZ Car, SW Vel, X Pup, T Mon and l Car) were observed aspart of a long-term programme at Mt John University Observatory. Radialvelocities were determined with the line bisector technique, and have aprecision of ~300 ms-1. Velocity differences as large as 30kms-1 were found for Hα and CaII when referenced to themetallic line velocity curves, but more subtle variations (of 1-2kms-1) were also detected in many other species. Pulsationalphase anticorrelations are found between lines of SiII and BaII,confirming the propagation time delay between line-forming layersproducing these two species. We find that the amplitude and phasedifferences between the various species increase with period. Period-luminosity relations for Galactic Cepheid variables with independent distance measurementsIn this paper, we derive the period-luminosity (PL) relation forGalactic Cepheids with recent independent distance measurements fromopen cluster, Barnes-Evans surface brightness, interferometry and HubbleSpace Telescope astrometry techniques. Our PL relation confirms theresults from recent works, which showed that the Galactic Cepheidsfollow a different PL relation to their Large Magellanic Cloud (LMC)counterparts. Our results also show that the slope of the Galactic PLrelation is inconsistent with the LMC slope with more than 95 per centconfidence level. We apply this Galactic PL relation to find thedistance to NGC 4258. Our result of μo= 29.49 +/- 0.06 mag(random error) agrees at the ~1.4σ level with the geometricaldistance of μgeo= 29.28 +/- 0.15 mag from water masermeasurements. Period-Luminosity Relations for Classical CepheidsBVIJHK period-luminosity relations for classical cepheids in the galaxyand magellanic clouds which pulsate in the fundamental mode are obtainedon the basis of four samples. The period-luminosity relations for theBVI bands obtained here are more accurate than the analogous relationsexisting up to the present. Period-luminosity relations in terms of Wfunctions are also obtained for these samples and have the same accuracyas the currently existing analogous relations. Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin iThis 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 Calibration of the distance scale from galactic Cepheids. I. Calibration based on the GFG sampleNew estimates of the distances of 36 nearby galaxies are presented basedon accurate distances of galactic Cepheids obtained by Gieren et al.(1998) from the geometrical Barnes-Evans method. The concept ofsosie'' is applied to extend the distance determination toextragalactic Cepheids without assuming the linearity of the PLrelation. Doing so, the distance moduli are obtained in astraightforward way. The correction for extinction is made using twophotometric bands (V and I) according to the principles introduced byFreedman & Madore (1990). Finally, the statistical bias due to theincompleteness of the sample is corrected according to the preceptsintroduced by Teerikorpi (1987) without introducing any free parameters(except the distance modulus itself in an iterative scheme). The finaldistance moduli depend on the adopted extinction ratioRV/RI and on the limiting apparent magnitude ofthe sample. A comparison with the distance moduli recently published bythe Hubble Space Telescope Key Project (HSTKP) team reveals a fairagreement when the same ratio RV/RI is used butshows a small discrepancy at large distance. In order to bypass theuncertainty due to the metallicity effect it is suggested to consideronly galaxies having nearly the same metallicity as the calibratingCepheids (i.e. Solar metallicity). The internal uncertainty of thedistances is about 0.1 mag but the total uncertainty may reach 0.3 mag.The table of the Appendix and Table 3 are available in electronic format 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/383/398, and on ouranonymous ftp-server www-obs.univ-lyon1.fr (pub/base/CEPHEIDES.tar.gz). Rotational velocities of A-type stars. I. Measurement of v sin i in the southern hemisphereWithin the scope of a Key Programme determining fundamental parametersof stars observed by HIPPARCOS, spectra of 525 B8 to F2-type starsbrighter than V=8 have been collected at ESO. Fourier transforms ofseveral line profiles in the range 4200-4500 Å are used to derivev sin i from the frequency of the first zero. Statistical analysis ofthe sample indicates that measurement error is a function of v sin i andthis relative error of the rotational velocity is found to be about 6%on average. The results obtained are compared with data from theliterature. There is a systematic shift from standard values from\citet{Slk_75}, which are 10 to 12% lower than our findings. Comparisonswith other independent v sin i values tend to prove that those fromSlettebak et al. are underestimated. This effect is attributed to thepresence of binaries in the standard sample of Slettebak et al., and tothe model atmosphere they used. Based on observations made at theEuropean Southern Observatory (ESO), La Silla, Chile, in the frameworkof the Key Programme 5-004-43K. Table 4 is only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5)or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/381/105 Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statisticsThe 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 Research Note Hipparcos photometry: The least variable starsThe data known as the Hipparcos Photometry obtained with the Hipparcossatellite have been investigated to find those stars which are leastvariable. Such stars are excellent candidates to serve as standards forphotometric systems. Their spectral types suggest in which parts of theHR diagrams stars are most constant. In some cases these values stronglyindicate that previous ground based studies claiming photometricvariability are incorrect or that the level of stellar activity haschanged. Table 2 is 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/367/297 The proper motions of fundamental stars. I. 1535 stars from the Basic FK5A direct combination of the positions given in the HIPPARCOS cataloguewith astrometric ground-based catalogues having epochs later than 1939allows us to obtain new proper motions for the 1535 stars of the BasicFK5. The results are presented as the catalogue Proper Motions ofFundamental Stars (PMFS), Part I. The median precision of the propermotions is 0.5 mas/year for mu alpha cos delta and 0.7mas/year for mu delta . The non-linear motions of thephotocentres of a few hundred astrometric binaries are separated intotheir linear and elliptic motions. Since the PMFS proper motions do notinclude the information given by the proper motions from othercatalogues (HIPPARCOS, FK5, FK6, etc.) this catalogue can be used as anindependent source of the proper motions of the fundamental stars.Catalogue (Table 3) is only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strastg.fr/cgi-bin/qcat?J/A+A/365/222 The excitation and kinematical properties of H2 and [Feii] in the HH 46/47 bipolar outflowLong-slit spectra of the molecular outflow Herbig-Haro (HH) 46/47 havebeen taken in the J and K near-infrared bands. The observedH2 line emission confirms the existence of a bright andextended redshifted counter-jet outflow south-west of HH 46. In contrastwith the optical appearance of this object, we show that this outflowseems to be composed of two different emission regions characterized bydistinct heliocentric velocities. This implies an acceleration of thecounter-jet. The observed [Feii] emission suggests an average extinctionof 7-9 visual magnitudes for the region associated with the counter-jet.Through position-velocity diagrams, we show the existence of differentmorphologies for the H2 and [Feii] emission regions in thenorthern part of the HH 46/47 outflow. We have detected for the firsttime high-velocity (-250kms-1) [Feii] emission in the regionbridging HH 46 to HH 47A. The two strong peaks detected can beidentified with the optical positions B8 and HH 47B. The H2excitation diagrams for the counter-jet shock suggest an excitationtemperature for the gas of Tex~2600K. The lack of emissionfrom the higher energy H2 lines, such as the 4-3 S(3)transition, suggests a thermal excitation scenario for the origin of theobserved emission. Comparison of the H2 line ratios withvarious shock models yielded useful constraints about the geometry andtype of these shocks. Planar shocks can be ruled out whereas curved orbow shocks (both J- and C-type) can be parametrized to fit our data. On the Variability of A6 to F9 SupergiantsHipparcos Satellite photometry of A6 to F9 supergiants reveals theiractivity. A few are especially quiescient. A0-A5II stars are examinedto help connect this study with that of earlier supergiants. Moderate-Resolution Near-Infrared Spectroscopy of Cool Stars: A New K-Band LibraryI present an atlas of near-infrared K-band spectra of 31 late-typegiants and supergiants and two carbon stars. The spectra were obtainedat resolving powers of 830 and 2000, and have a signal-to-noise ratio>~100. These data are complemented with results from similar existinglibraries in both K and H band, and they are used to identify varioustools useful for stellar population studies at moderate resolution. Ifocus on several of the most prominent absorption features and (1)investigate the effects of spectral resolution on measurements of theirequivalent width (EW), (2) examine the variations with stellarparameters of the EWs, and (3) construct composite indices as indicatorsof stellar parameters and of the contribution from excess continuumsources commonly found in star-forming and AGN galaxies. Among thefeatures considered, the 12CO (2,0) and 12CO (6,3)bandheads together with the Si I 1.59 μm feature, first proposed byOliva, Origlia, and coworkers, constitute the best diagnostic set forstellar spectral classification and for constraining the excesscontinuum emission. The Ca I 2.26 μm and Mg I 2.28 μm featuresoffer alternatives in the K band to the 12CO (6,3) bandheadand Si I feature. Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutionsThe FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over more than twocenturies and summarized in the FK5. Part I of the FK6 (abbreviatedFK6(I)) contains 878 basic fundamental stars with direct solutions. Suchdirect solutions are appropriate for single stars or for objects whichcan be treated like single stars. From the 878 stars in Part I, we haveselected 340 objects as "astrometrically excellent stars", since theirinstantaneous proper motions and mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,199 of the stars in Part I are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives in addition to the SI mode the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(I) proper motion in the single-star mode is 0.35 mas/year. This isabout a factor of two better than the typical HIPPARCOS errors for thesestars of 0.67 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(I) proper motions have atypical mean error of 0.50 mas/year, which is by a factor of more than 4better than the corresponding error for the HIPPARCOS values of 2.21mas/year (cosmic errors included). A Second Catalog of Orbiting Astronomical Observatory 2 Filter Photometry: Ultraviolet Photometry of 614 StarsUltraviolet photometry from the Wisconsin Experiment Package on theOrbiting Astronomical Observatory 2 (OAO 2) is presented for 614 stars.Previously unpublished magnitudes from 12 filter bandpasses withwavelengths ranging from 1330 to 4250 Å have been placed on thewhite dwarf model atmosphere absolute flux scale. The fluxes wereconverted to magnitudes using V=0 for F(V)=3.46x10^-9 ergs cm^-2 s^-1Å^-1, or m_lambda=-2.5logF_lambda-21.15. This second catalogeffectively doubles the amount of OAO 2 photometry available in theliterature and includes many objects too bright to be observed withmodern space observatories. Radial velocities of HIPPARCOS southern B8-F2 type starsRadial velocities have been determined for a sample of B8-F2 type starsobserved by the Hipparcos satellite. Observations were obtained withinthe framework of an ESO key-program. Radial velocities have beenmeasured using a cross-correlation method, the templates being a grid ofsynthetic spectra. The obtained precision depends on effectivetemperature and projected rotational velocity of the star as well as ona possible asymmetry of the correlation peak generally due to secondarycomponents. New spectroscopic binaries have been detected from theseasymmetries and the variability of the measured radial velocity.Simulations of binary and triple systems have been performed. Forbinaries our results have been compared with Hipparcos binary data.Adding the variable radial velocities, the minimum binary fraction hasbeen found 60% for physical systems. Radial velocities have beendetermined for 581 B8-F2 stars, 159 being new. Taking into accountpublished radial velocities, 39% south A-type stars with V magnitudelower than 7.5 have a radial velocity. Based on observations obtained atthe European Southern Observatory (ESO, La Silla, Chile) and on datafrom the ESA Hipparcos astrometry satellite.}\fnmsep \thanks{Tables 7, 8and 9 are only available in electronic form at the CDS via anonymous ftpto cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html The ultraviolet variations of the post-AGB star HD 89353Based on an analysis of all low resolution spectra of HD 89353 (HR 4049)obtained with the International Ultraviolet Explorer (IUE) over severalyears and uniformly reprocessed, we report on large ultravioletvariations for this star whose amplitude increases towards longwavelengths. Ultraviolet maximum and minimum occur respectively at phase0.52 and 0.92 of Waelkens et al. (1991) ephemeris which suggests thatultraviolet and optical variations occur in phase. The ultravioletenergy distribution of HD 89353 is very deficient compared to that ofthe standard A6Ib star, HD 80404, and compared to the predictions of anATLAS 9 model (Teff = 7500K, log g = 2.0 and [M/H]= -5.0)which bests fit the optical continuum. The ultraviolet flux deficiencyscales as <~mbda(-1) , a trend already noted earlier (Waelkens et al.1995). The most likely interpretation is that variable circumstellarextinction drives the ultraviolet and optical variations as proposed byWaelkens et al. (1991). Based on data from the International UltravioletExplorer The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiantsWe present X-ray data for all late-type (A, F, G, K, M) giants andsupergiants (luminosity classes I to III-IV) listed in the Bright StarCatalogue that have been detected in the ROSAT all-sky survey.Altogether, our catalogue contains 450 entries of X-ray emitting evolvedlate-type stars, which corresponds to an average detection rate of about11.7 percent. The selection of the sample stars, the data analysis, thecriteria for an accepted match between star and X-ray source, and thedetermination of X-ray fluxes are described. Catalogue only available atCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html The Cepheid period-luminosity zero-point from HIPPARCOS trigonometrical parallaxesHipparcos trigonometrical parallaxes of Cepheid variables are used toderive a zero-point for the period-luminosity (PL) relation. Adopting aslope from the Large Magellanic Cloud (LMC), the relation is found to be=-2.81 log P-1.43. The standard error of the zero-point is0.10 mag. Together with metallicity corrections this corresponds to adistance modulus of 18.70+/-0.10 for the LMC and 24.77+/-0.11 for M31.Some implications of these results are discussed. Estimates of theHubble constant (H_0) that are based on Cepheid observations togetherwith an adopted LMC distance modulus of 18.50 will on average now needto be decreased by ~10 per cent. However, metallicity corrections, whichhave frequently been ignored, will result in the actual percentagechange varying with the sample of galaxies studied. Calibration of RRLyrae absolute magnitudes using the LMC and M31 Cepheid distancesimplies an age for the oldest Galactic globular clusters of ~11 Gyr. Theparallax data show that the period of Polaris corresponds to firstovertone pulsation. Classification and Identification of IRAS Sources with Low-Resolution SpectraIRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed. A catalogue of [Fe/H] determinations: 1996 editionA 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 Parameters of the JHK light curves of classical Cepheids and the interstellar-extinction LAW.Not Available 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. Search for resonance effects in long period Cepheids.Light curves of classical Cepheids with period longer than 8 days havebeen Fourier decomposed with the purpose of studying the characteristicsof high order Fourier parameters, and to detect possible effects ofresonances between pulsation modes other than the well known resonanceat P~10d. The possible effects of two expected resonances have beententatively identified: P_0_/P_1_=3/2 at P_0_~24 d and P_0_/P_3_=3 atP_0_~27d. The identification is not completely certain owing to the poornumber of Cepheids. The limitation could be overcome by observingaccurately other relatively faint Cepheids in our Galaxy, and severalCepheids in nearby galaxies. Colour excesses of F-G supergiants and Cepheids from Geneva photometry.A reddening scale for F-G supergiants and Cepheids is presented.Supergiants with low reddenings or in clusters form the basis of thecalibration. In this sense, it is entirely empirical. The data have beenobtained in the Geneva photometric system. Comparisons with otherreddening scales show no disagreement. The only problem is with Fernie'sscale for Cepheids (1990), where a systematic trend exists. Its originis not clear. It is suggested to extend the number of supergiants withindependently obtained colour excesses in order to test the existence ofa possible luminosity dependence of the calibration. A period-colourrelation for Cepheids is deduced, on the basis of the present reddeningcorrections. It gives strong support for V473 Lyr being a secondovertone pulsator. On the Abundances of Nitrogen and Sulfur in Late-B through F Supergiants AtmospheresAn extensive non-LTE analysis of NI and SI lines at the spectral regionaround lambda ~ 8700Angstroms was performed for late-B through Fsupergiants in order to determine the photospheric abundances of N and Sin such massive evolved stars. It was revealed that the abundances ofnitrogen in these stars show a rather large diversity ( ~ +/- 0.4 dex)around the mean of [N/H] =~ 0.3 relative to the Sun, being roughlydivided into three groups: (i) markedly large overabundances amountingto 0.6--0.7 dex, (ii) mild N-excesses of 0.3--0.4 dex, and (iii)near-solar (or slightly subsolar) [N/H]-values. The abundances of sulfurfor F-supergiants were found to be nearly homogeneous and not muchdifferent from the solar composition ([S/H] ~ -0.2), while those for theA-type generally show a tendency of S-excess (up to +0.8 dex)systematically increasing with T_eff. There also appears a trend ofmass-dependence as well as a possibility of mutual correlation regardingthe values of [N/H] and [S/H] in those A-supergiants. It was confirmedthat the extent of the N-excess in A--F supergiants tends to depend onthat of sodium as [N/H] =~ [Na/H]. 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. Some problems of chemical composition of stellar atmospheres.Not Available An atlas of ultraviolet P Cygni profilesWe have selected spectra of 232 stars from the International UltravioletExplorer (IUE) archives for inclusion in an atlas intended for varioususes but tailored especially for the study of stellar winds. The atlascovers the range in spectral types from O3 to F8. The full atlas coversthe reduced and normalized high resolution spectra from the IUE long-and short-wavelength spectrographs. Here we discuss the selection of thestars and the data reduction, and we present in velocity units theprofiles of lines formed in the stellar winds. The selected lines covera wide range of ionizations, allowing a comparison of the profiles fromdifferent ions in the wind of each star and a comparison of thedifferent wind lines as a function spectral type and luminosity. We alsopresent the basic data on the program stars to facilitate study of thedependence of wind features on stellar parameters such as luminosity,temperature, escape velocity, and v sin i. We provide an overview of thecharacteristic behavior of the wind lines in the H-R diagram. Thecomplete spectra are available in digital form through the NASAAstrophysics Data System (ADS). We offer a description of the electronicdatabase that is available through the ADS and guidelines for obtainingaccess to that database.
Submit a new article

• - No Links Found -