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A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars
Rotational velocity vsin i and mean radial velocity are presented for asample of 231 Ib supergiant stars covering the spectral region F, G andK. This work is the second part of the large survey carried out with theCORAVEL spectrometer to establish the behavior of the rotation for starsevolving off the main sequence (De Medeiros & Mayor 1999). Thesedata will add constraints to the study of the rotational behavior inevolved stars, as well as solid information concerning tidalinteractions in binary systems and on the link between rotation,chemical abundance and activity in stars of intermediate masses. Basedon observations collected at the Haute-Provence Observatory,Saint-Michel, France and at the European Southern Observatory, La Silla,Chile Table 1 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/395/97
| Lick Spectral Indices for Super-Metal-rich Stars
We present Lick spectral indices for a complete sample of 139 candidatesuper-metal-rich stars of different luminosity classes (MK type from Ito V). For 91 of these stars we were able to identify, in anaccompanying paper, the fundamental atmosphere parameters. This confirmsthat at least 2/3 of the sample consists of stars with [Fe/H] in excessof +0.1 dex. Optical indices for both observations and fiducialsynthetic spectra have been calibrated to the Lick system according toWorthey et al. and include the Fe I indices of Fe5015, Fe5270, andFe5335 and the Mg I and MgH indices of Mg2 and Mg b at 5180Å. The internal accuracy of the observations is found to beσ(Fe5015)=+/-0.32 Å, σ(Fe5270)=+/-0.19 Å,σ(Fe5335)=+/-0.22 Å, σ(Mg2)=+/-0.004 mag,and σ(Mg b)=+/-0.19 Å. This is about a factor of 2 betterthan the corresponding theoretical indices from the synthetic spectra,the latter being a consequence of the intrinsic limitations in the inputphysics, as discussed by Chavez et al. By comparing models andobservations, we find no evidence for nonstandard Mg versus Fe relativeabundance, so [Mg/Fe]=0, on the average, for our sample. Both theWorthey et al. and Buzzoni et al. fitting functions are found tosuitably match the data and can therefore confidently be extended forpopulation synthesis application also to supersolar metallicity regimes.A somewhat different behavior of the two fitting sets appears, however,beyond the temperature constraints of our stellar sample. Its impact onthe theoretical output is discussed, as far as the integratedMg2 index is derived from synthesis models of stellaraggregates. A two-index plot, such as Mg2 versus Fe5270, isfound to provide a simple and powerful tool for probing distinctiveproperties of single stars and stellar aggregates as a whole. The majoradvantage, over a classical CM diagram, is that it is both reddeningfree and distance independent. Based on observations collected at theInstituto Nacional de Astrofísica, Optica y Electrónica(INAOE) ``G. Haro'' Observatory, Cananea (Mexico).
| Observations and Atmospheric Parameters of Super-Metal-rich Candidates
The spectroscopic properties of a sample of 92 Population I bright stars(V<8) with literature values of [Fe/H]>=+0.1 are reviewed in orderto study the metallicity scale at supersolar regimes. For 73 of thesecandidate super-metal-rich (SMR) stars we identified the photosphericfiducial parameters (Teff, logg, [M/H]) from among publishedparameter sets via a comparison of new observations in the wavelengthrange 5034-5398 Å with synthetic spectra derived from the 1997database of Chavez et al. As a main issue in our analysis, we find thata ``genuine'' SMR stellar component in the Galactic disk exists withmore than one-fourth of the stars in our sample fulfilling the criterion[Fe/H]>=0.2 dex, and three of them as rich as [Fe/H]>+0.4 dex.Based on observations collected at the INAOE ``G. Haro'' Observatory,Cananea (Mexico).
| The central depth of the Ca II triplet lines as a discriminant of chromospheric activity in late type stars
Not Available
| Quantitative spectral classification of galactic disc K-M stars from spectrophotometric measurements
New spectral observations for 47 southern galactic red supergiantsobtained with the new RUBIKON spectrophotometer (developed at theAstronomisches Institut der Ruhr-Universitat Bochum) at the Bochum 61-cmtelescope on La Silla are presented. The spectra range from 4800 to 7700A and their resolution is 10 A. The mean error of absolute fluxes is0.028 mag and that of relative fluxes 0.021 mag. The spectra will beavailable at the Strasbourg Stellar Database (CDS). Together with datataken from recently published spectral catalogues, the new observationshave been used to define spectral indices as measures of the strengthsof the following features: Fe i+TiOalpha_1, Mgb+TiOalpha_0,NaD+TiOgamma'_1, TiOgamma'_0 and TiOgamma_1 systems. The indices havebeen checked against errors introduced by reductions, interstellarreddening and different resolutions of different spectral catalogues,and have been found to be very insensitive to all these effects.Therefore, different catalogues may be combined without any loss ofaccuracy and homogeneity. The mean error of a single index has beenfound to be 0.011 mag. For stars from K4 to M7, a strong temperaturedependence is found for all indices. For the Fe i+TiO and especially theMgb+TiO features, a strong dependence on luminosity has also beenobserved. These indices therefore have been combined to form aluminosity index, while the others together form a spectral index. Thecombined indices have been calibrated in terms of MK data using thestepwise linear regression technique, and may be used for quantitativetwo- dimensional spectral classification of late K- and M-type stars.The mean error of the classification is 0.6 of spectral subtype and 0.8of luminosity class, which is much higher than would be expected fromthe uncertainty of the indices alone (which, e.g., for an M4 giantcorrespond to an uncertainty of 0.1 of spectral subtype and 0.3 ofluminosity class). This may be explained by the uncertainty of theoriginal MK classifications and the variability of some programme stars.
| Classification and Identification of IRAS Sources with Low-Resolution Spectra
IRAS 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 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
| A library of H band stellar spectra for stellar population analysis purposes.
A sample of 37 stars of luminosity classes I, III, V, including few SMRstars observed in the H band with a medium resolution (R=1500-2000) ispresented. This sample of flux calibrated spectra is intended to widenexisting stellar libraries. A new IR spectrograph, ISIS/IR, foreseen forCFHT has been used. Its main characteristics are briefly described.Stellar spectra obtained with this new spectrograph are compared tosimilar data obtained with the ESO NTT IRSPEC spectrograph. Thebehaviour of some prominent features is described and it is shown thatthe COλ1.60/SiIλ1.60 line ratio is a good luminosityindicator for stellar types later than K0.
| 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.
| Metal enrichment in elliptical galaxies and globular clusters through the study of iron and H-Beta spectral indices
Chemical evolution of elliptical galaxies and globular clusters isaddressed through a combined study of the iron indices at 5270 and 5335A, and of the H-Beta line strength. The observational database of 74standard stars (both dwarfs and giants) referred to in a previous paper(Buzzoni et al. (1992)) complemented with the data of Faber et al.(1985) and Gorgas et al. (1993) allowed us to explore here Fe and H-Betaindex dependence on stellar temperature, gravity, and metallicity. Thederived fitting functions were then included into Buzzoni's (1989) codefor population synthesis in order to derive expected integrated indicesfor simple stellar populations and compare with observations. Partitionof metals in the current chemical mix of galaxies and globulars has beenconstrained supporting the claim that light alpha elements might beenhanced in the globular cluster metal-poor population. An alternativeconclusion resting on the standard framework with (alpha/Fe) = 0 wouldrequire a systematically larger age, about 18-20 Gyr. Iron and magnesiumin ellipticals are found in average solar but a systematic trend of(Mg/Fe) vs global metallicity does exist with iron more deficient withrespect to magnesium at high Z. We conclude that this effect mightindicate that Fe abundance per unit mass in the galaxies is constant(suggesting a constant rate per unit mass of SN I events) while lightmetals supplied by SNe II should have been more effectively enrichedwith increasing galactic total mass.
| The CA II triplet lines in cool stars
Observations of the infrared triplet lines of ionized calcium arepresented for 91 stars brighter than m_v_=+7.0 in the spectral rangeF8-M4 of all luminosity classes and over a range of metallicities [Fe/H]from -0.65 to +0.60. The above spectra have been obtained at a spectralresolution of 0.4 A with a coude echelle spectrograph using the ThomsonCCD as the detector. This study has been undertaken primarily toinvestigate the dependence of the Ca II triplet strengths over the broadrange of atmospheric parameters like luminosity, temperature andmetallicity. The Ca II triplet lines are a powerful diagnostic of thestellar populations in galaxies because of their sensitivity to theabove parameters. Our detailed analysis indicates a strong correlationbetween the equivalent width of the Ca II triplet lines and surfacegravity, much stronger in metal rich stars than in metal poor stars. TheCa II equivalent widths are fairly insensitive to temperature over therange of luminosity covered. However, they are found to be quitesensitive to metallicity, more conspicuously in supergiants than ingiants and dwarfs. Observations are compared with recent theoreticalcalculations of these lines in NLTE atmospheres.
| CCD observations of the H-alpha line in late G and K supergiants and their interpretation
CCD echelle spectra of the H-alpha line at 6563 A have been obtained fora sample of 30 G and K supergiants with a spectral resolution of about0.24 A. The data clearly indicate that the observed H-alpha profile is adeep absorption, implying large optical depths in the chromosphere.Also, the line cores are blueshifted in all the stars which suggests thechromospheres are expanding outward. Detailed radiative transfercalculations of H-alpha have been carried out in a spherically symmetricatmosphere with outward-positive velocity and temperature gradients,including explicitly the effects of ionization. The H-alpha lineprofiles have been computed for a wide range of parameters in order toreproduce the observed features of the line. Within the framework of ourmodel, the calculations reinforce the idea that the nonthermalvelocities have to be as large as 25-30 km/s to explain the large widthsof the observed profiles. The rates of mass outflow have been calculatedto lie in the range 10 exp -8 to 10 exp -9 solar mass/yr.
| The chemical composition of Magellanic Cloud Cepheids and nonvariable supergiants
Results of abundance analyses of 14 Cepheids and nonvariable supergiantsin the Magellanic Clouds are presented along with comparison data onfour Galactic objects. Elemental abundances derived include Li, C, N, O,the alpha-elements, the Fe peak, and limited data on the heavy elements.Only HV 5497 in the LMC shows any detectable Li among the Cloud objects.The present CNO data, when combined with previous results, suggest adisparity between the LMC and the SMC supergiants in that the SMC starshave an essentially constant O/Fe ratio, while the LMC stars do not. TheO/Fe ratios within both Clouds are lower than the ratio found inGalactic stars of similar metallicity, but are comparable to the O/Feratios found in Galactic supergiants. For heavier elements, previousresults which indicate the light s- and r-process elements (Sr, Y, Zr)show Galactic ratios with respect to Fe, but that the heavy s- andr-process elements (Ba-Sm) are enhanced in the Clouds, are confirmed.
| The magnesium Mg2 index as an indicator of metallicity in elliptical galaxies
A quantitative calibration of the Mg2 index is attempted deriving ametallicity scale for elliptical galaxies. The dependence of the indexon stellar temperature, gravity, and metallicity has been studiedthrough spectroscopic observations of 87 standards applying the derivedcalibration to models for stellar population synthesis. Buzzoni's (1989)computational code has been used to explore the behavior of the indexversus age, IMF, and metallicity of simple stellar populations,inferring galactic metallicity for the Davies et al. (1987) extensiveobservational database. It appears that ellipticals are old metal-richsystems, with age about 15 Gyr and (Fe/H) = + 0.15. A large spread ofnearly one order of magnitude is, however, derived for metallicity amongsingle galaxies confirming that (Fe/H) is the driving parameter inducingthe color spread in the galaxy population. Evolutionary behavior of Mg2is briefly discussed giving its expected variations at early epochs forcomparison with high-redshift galaxies.
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
| Role of nonthermal velocity fields in determining the H-alpha widths in supergiant chromospheres
Radiative transfer calculations of the H-alpha line in sphericallysymmetric, expanding chromospheres explain the large widths of the lineobserved in late G and K supergiants. The role of various dynamicalprocesses as well as that of opacity in determining the H-alpha width isillustrated. The H-alpha line profile is basically characterized bylarge optical depths and large Doppler broadening velocity. Thecalculations show that the existence of large microturbulence has to beinvoked in the chromosphere to understand the observed widths.
| M Giant Populations and Galactic Structure
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990MNRAS.247..227F&db_key=AST
| Mass-losing M supergiants in the solar neighborhood
A list of the 21 mass-losing red supergiants (20 M type, one G type; Lgreater than 100,000 solar luminosities) within 2.5 kpc of the sun iscompiled. These supergiants are highly evolved descendants ofmain-sequence stars with initial masses larger than 20 solar masses. Thesurface density is between about 1 and 2/sq kpc. As found previously,these stars are much less concentrated toward the Galactic center thanW-R stars, which are also highly evolved massive stars. Although withconsiderable uncertainty, it is estimated that the mass return by the Msupergiants is somewhere between 0.00001 and 0.00003 solar mass/sq kpcyr. In the hemisphere facing the Galactic center there is much less massloss from M supergiants than from W-R stars, but, in the anticenterdirection, the M supergiants return more mass than do the W-R stars. Theduration of the M supergiant phase appears to be between 200,000 and400,000 yr. During this phase, a star of initially at least 20 solarmasses returns perhaps 3-10 solar masses into the interstellar medium.
| A list of MK standard stars
Not Available
| Supergiants and the Galactic metallicity gradient. II - Spectroscopic abundances for 64 distant F- to M-type supergiants
The metallicity gradient in the Galactic disk from in situ stars withvisual magnitude ranging from 6 to 10 is analyzed. Atmosphericparameters and detailed chemical abundances for 64 Population Isupergiants of spectral types F through M and luminosity classes Iathrough II have been determined. The derived Fe/H ratios ranging from-0.5 to + 0.7 show a mean value of +0.13 with an estimated uncertaintyof + or - 0.2. A subset of 25 supergiants fainter than 7th magnitudelying in the direction of the Galactic center shows a Fe/H mean of +0.18+ or - 0.04, while a similar sample of 15 faint supergiants lying in thedirection of the Galactic anticenter shows a lower Fe/H mean of +0.07 +or - 0.06. For a sample of bright supergiants analyzed by Luck andLambert (1985), the mean abundance pattern for all 64 stars showed thefollowing: deficient C and O along with enhancement of N, indicatingmixing of CNO-cycled material to the stellar surfaces; an apparent Srenhancement attributed to departures from LTE; and an essentially solarpattern of other chemical elements.
| The Perkins catalog of revised MK types for the cooler stars
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
| Consequences of a chromospheric temperature rise on the formation of the H-alpha line in late-type supergiants
Computations of the H-alpha line profiles were performed in a non-LTEmoving chromosphere with temperature rise to simulate the observedH-alpha characteristics in G and K supergiants. The comoving frameradiative transfer code was modified to incorporate explicitly theeffects of hydrogen ionization. The sensitivity of H-alpha profiles to avariety of temperature structures, velocity gradients, and chromosphericextents and densities is examined and illustrated. Comparison of theobserved profiles to computed ones gives total hydrogen densities in therange between 10 to the 9th and 10 to the 11th/cu cm at the base of theline forming region. Integrated chromospheric optical depths in therange of 50-5000 and expansion velocities in the range of 0.25-2 timesthe maximum random (microturbent and thermal) velocity are found. Themass loss rate is inferred to be in the range between 10 to the -7th and10 to the -9th solar masses/year.
| 1988 Revised MK Spectral Standards for Stars GO and Later
Not Available
| Are the red supergiants Epsilon Peg and 12 PUP victims of mild s-processing?
An abundance analysis of eight G and K supergiants has been performedwith particular emphasis on two stars, Epsilon Peg and 12 Pup. It hasbeen reported (Kovacs, 1983) that these two stars exhibit selectiveenhancement of Ba and, in the case of 12 Pup, Sr. Such a pattern ofabundance enhancement would occur for very mild s-processing followed byextensive pollution of the star's outer envelope with this processedmaterial. This type of mixing is not predicted by current models ofstellar evolution. The previous Ba and Sr abundances were based on verystrong lines of Ba II and Sr II and such lines are sensitive tomicroturbulence and conditions in the higher layers of the stellaratmosphere. This analysis compares the Ba II and Sr II line-strengths inEpsilon Peg and 12 Pup with six other cool supergiants and also utilizesweak Ba I and Sr I lines seen in the spectra of these stars. Noenhancements of Ba or Sr, relative to the other supergiants, are foundfor Epsilon Peg or 12 Pup. In addition, calculations of the abundancesproduced by mild s-processing followed by extensive mixing with theouter envelope show that Co and Sc should also be enhancedsubstantially. Such enhancements are not observed in any of thesupergiants.
| Normal supergiants and their imitations. I - Sodium as a mass indicator?
Considering the possibility for a low-mass celestial body to attain highluminosity, characteristic for a normal supergiant, and mimicspectroscopic and photometric behavior of the latter, a method isproposed that could be possibly used to distinguish between supergiantsand their limitations. In this method, surface abundance of Na-23 wasused as a probable mass indicator, deriving the sodium-to-mass relationfor a sample of 34 well-observed stars. Special attention was paid tothe parameter-related errors and non-LTE effects for the Na I lines inthe visible. To account for the initial sodium content, all sodiumabundances were normalized, using the Na/Fe relation derived fromsolar-type dwarfs. The plot of the normalized sodium abundance againststellar mass has revealed a direct relationship between the twoparameters, suggesting a real interdependence. The classical Cepheid XCyg, believed to be a true intermediate-mass star, was well within thehighly scattered relation.
| Expanding chromospheres of late G and K supergiants
The radiative transfer problem in non-LTE moving atmospheres has beenexplicitly solved for H-alpha line profiles. These computations havebeen done for a schematic model of the line-forming region over a widerange of optical depths and velocity gradients in order to cover theobserved characteristics in 23 G and K supergiants. The best theoreticalfits yield optical depths in the range 10-500 and velocity fields in therange 0.5-3 Doppler widths. The computed mass-flow rates lie in therange of 10 to the -5th to 10 to the -7th solar masses/yr; the higherthe extent of the line-forming region, the lower the mass-loss rates.The effect of the extent on the H-alpha emission components has alsobeen investigated in some detail.
| E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
| IRAS catalogues and atlases - Atlas of low-resolution spectra
Plots of all 5425 spectra in the IRAS catalogue of low-resolutionspectra are presented. The catalogue contains the average spectra ofmost IRAS poiont sources with 12 micron flux densities above 10 Jy.
| The MK classification and its calibration
The system of spectral classification is described as it has developedfrom the original Yerkes Atlas (Morgan, Keenan, Kelman 1943) untiltoday. The word 'developed' is used because any system that is to remainuseful must be flexible enough to adapt not only to improved techniquesof measurement but also to new theoretical insights into the variablesthat actually determine the energy spectrum of a star in all itsfascinating but sometimes frustrating detail. The discussion does notconsider the criteria of classification but is confined to the resultingset of temperature types and luminosity classes. Chemical composition isexamined as a third variable. Tabulated and plotted informationincludes: MK temperature subclasses; lists of MK types of fainter stars;published calibrations of luminosity classes for early-type stars;calibration of MK luminosity classes for types later than F8; thedistribution among groups of the 426 stars in the author's current listof best types; and the effects of metal deficiencies on spectra of KOIII stars. The revised MK classification can be applied to all but a fewpercent of the stars later in type than GO. For the two-thirds of thesethat have approximately solar composition no abundance index is needed;for most of the remainder one abundance index suffices.
| 1985 revised MK spectral standards : stars GO and later
Not Available
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| קבוצת-כוכבים: | כלב גדול |
| התרוממות ימנית: | 07h16m36.80s |
| סירוב: | -23°18'56.0" |
| גודל גלוי: | 4.79 |
| מרחק: | 1923.077 פארסק |
| תנועה נכונה: | -0.6 |
| תנועה נכונה: | 4.1 |
| B-T magnitude: | 6.937 |
| V-T magnitude: | 5.001 |
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