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Galactic distributions and statistics of the HD stars in the michigan spectral catalogue.
Not Available
| The Tennessee State University Automatic Spectroscopic Telescope: Data Processing and Velocity Variation of Cool Giants
This paper discusses data reduction for an echelle spectrograph we havedeveloped for an automatic telescope at Tennessee State University andare using to monitor radial velocities and line profiles of cool giantand supergiant stars. Although our approach to data reduction is ratherconventional, we discuss flat-fielding and extraction of velocities inways that should be of general interest, establish a transformation tothe IAU radial velocity system (+0.35 +/- 0.09 km s-1), anddetermine the external precision for measured velocities (0.10-0.11 kms-1). Also, we present results of the first 2-3 years ofmonitoring radial velocities in about 120 cool giants and compare thoseresults with the level of variability found with photometry. These newdata confirm the widely held understanding that K and M giants are allradial velocity variables at the level of 0.1 km s-1.
| Infrared Study of J-Type Carbon Stars Based on Infrared Astronomical Satellite, Two Micron All Sky Survey, and Infrared Space Observatory Data
We collected 113 J-type carbon stars from the published literature.Observations from 2MASS, IRAS, and ISO show that, except for silicatecarbon stars in the J-type carbon star domain, the infrared propertiesof the other J-type carbon stars are quite similar to those of ordinarycarbon stars. The above results imply that the chemical peculiarity ofenhanced 13C for J-type carbon stars is not reflected in theinfrared region. In addition, the possible evolutionary scenario andbinarity for J-type carbon stars are also discussed.
| Galactic model parameters for field giants separated from field dwarfs by their 2MASS and V apparent magnitudes
We present a method which separates field dwarfs and field giants bytheir 2MASS and V apparent magnitudes. This method is based onspectroscopically selected standards and is hence reliable. We appliedit to stars in two fields, SA 54 and SA 82, and we estimated a full setof Galactic model parameters for giants including their total localspace density. Our results are in agreement with the ones given in therecent literature.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Cool carbon stars in the halo: A new survey based on 2MASS
We present the first results of a new survey for finding cool N-typecarbon (C) stars in the halo of the Galaxy. Candidates were firstselected in the 2MASS Second Incremental Release database withJHKs colours typical of red AGB C stars and Ks< 13, and subsequently checked through medium resolution slitspectroscopy. We discovered 27 new C stars plus one known previously andtwo similar objects in the Fornax and Sculptor dwarf galaxies. Wedetermine and discuss the properties of our sample, including opticaland near-infrared colours, radial velocities, as well as Hαemission and variability that are frequent, all these characteristicsbeing compatible with an AGB C-type classification. Surprisingly, of the30 studied objects, 8 were found to have small but measurable propermotions (μ) in the USNO-B1.0 catalogue, ranging over 8 < μ <21 mas yr-1 and opening the possibility that some objectscould perhaps be dwarf carbon stars. Yet, a detailed analysis based oncomparison with the sample of known carbon dwarfs leads us to considerthese μ as incompatible with the broader picture suggested by theother data taken as a whole. So, we adopt the view that all objects areof AGB type, i.e. luminous and distant. Because the stream ofSagittarius dwarf galaxy is known to be the dominant source of luminousC stars in the halo, we chose to determine distances for our sample byscaling them on the 26 known AGB C stars of the Sgr galaxy itself, whichare found to be, in the Ks-band, 0.5 mag less luminousthan the average LMC C stars for a given J-Ks colour. Theobtained distances of our halo stars range from 8 to 80 kpc from theSun. Then, examination of position and radial velocities show that abouthalf belong to the Sgr stream. Our findings suggest that numerous AGB Cstars remain to be discovered in the halo. Long term Ks-bandmonitoring would be of great value to ascertain distance estimatesthrough the period-luminosity relation, because a large fraction of oursample is probably made of Mira variables.Based on observations made at the European Southern Observatory, Chile(programs 67.B 0085AB, 69.B 0186A) and at the Haute Provence Observatory(France) operated by the Centre National de Recherche Scientifique,together with data from the 2MASS project (University of Massachusettsand IPAC/Caltech, USA).Appendices are only available in electronic form athttp://www.edpsciences.org
| Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 is onlyavailable 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/qcat?J/A+A/397/997
| Carbon-rich giants in the HR diagram and their luminosity function
The luminosity function (LF) of nearly 300 Galactic carbon giants isderived. Adding BaII giants and various related objects, about 370objects are located in the RGB and AGB portions of the theoretical HRdiagram. As intermediate steps, (1) bolometric corrections arecalibrated against selected intrinsic color indices; (2) the diagram ofphotometric coefficients 1/2 vs. astrometric trueparallaxes varpi are interpreted in terms of ranges of photosphericradii for every photometric group; (3) coefficients CR andCL for bias-free evaluation of mean photospheric radii andmean luminosities are computed. The LF of Galactic carbon giantsexhibits two maxima corresponding to the HC-stars of the thick disk andto the CV-stars of the old thin disk respectively. It is discussed andcompared to those of carbon stars in the Magellanic Clouds and Galacticbulge. The HC-part is similar to the LF of the Galactic bulge,reinforcing the idea that the Bulge and the thick disk are part of thesame dynamical component. The CV-part looks similar to the LF of theLarge Magellanic Cloud (LMC), but the former is wider due to thesubstantial errors on HIPPARCOS parallaxes. The obtained meanluminosities increase with increasing radii and decreasing effectivetemperatures, along the HC-CV sequence of photometric groups, except forHC0, the earliest one. This trend illustrates the RGB- and AGB-tracks oflow- and intermediate-mass stars for a range in metallicities. From acomparison with theoretical tracks in the HR diagram, the initial massesMi range from about 0.8 to 4.0 Msun for carbongiants, with possibly larger masses for a few extreme objects. A largerange of metallicities is likely, from metal-poor HC-stars classified asCH stars on the grounds of their spectra (a spheroidal component), tonear-solar compositions of many CV-stars. Technetium-rich carbon giantsare brighter than the lower limit Mbol =~ -3.6+/- 0.4 andcentered at =~-4.7+0.6-0.9 at about =~(2935+/-200) K or CV3-CV4 in our classification. Much like the resultsof Van Eck et al. (\cite{vaneck98}) for S stars, this confirms theTDU-model of those TP-AGB stars. This is not the case of the HC-stars inthe thick disk, with >~ 3400 K and>~ -3.4. The faint HC1 and HC2-stars( =~ -1.1+0.7-1.0) arefound slightly brighter than the BaII giants ( =~-0.3+/-1.3) on average. Most RCB variables and HdC stars range fromMbol =~ -1 to -4 against -0.2 to -2.4 for those of the threepopulation II Cepheids in the sample. The former stars show the largestluminosities ( <~ -4 at the highest effectivetemperatures (6500-7500 K), close to the Mbol =~ -5 value forthe hot LMC RCB-stars (W Men and HV 5637). A full discussion of theresults is postponed to a companion paper on pulsation modes andpulsation masses of carbon-rich long period variables (LPVs; Paper IV,present issue). This research has made use of the Simbad databaseoperated at CDS, Strasbourg, France. Partially based on data from theESA HIPPARCOS astrometry satellite. Table 2 is 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/390/967
| Reprocessing the Hipparcos data for evolved giant stars II. Absolute magnitudes for the R-type carbon stars
The Hipparcos Intermediate Astrometric Data for carbon stars have beenreprocessed using an algorithm which provides an objective criterion forrejecting anomalous data points and constrains the parallax to bepositive. New parallax solutions have been derived for 317 cool carbonstars, mostly of types R and N. In this paper we discuss the results forthe R stars. The most important result is that the early R stars (i.e.,R0 - R3) have absolute magnitudes and V-K colors locating them among redclump giants in the Hertzsprung-Russell diagram. The average absolutemagnitude MK for early R-type stars (with V - K < 4) hasbeen derived from a Monte-Carlo simulation implicitly incorporating allpossible biases. It appears that the simulated magnitude distributionfor a population with a true Gaussian distribution of mean MK= -2.0 and intrinsic standard deviation 1.0 mag provides a satisfactorymatch to the observed distribution. These values are consistent with theaverage absolute magnitude MK = -1.6 for clump red giants inthe solar neighborhood (Alves 2000). Further, early R-type stars arenon-variable, and their infrared photometric properties show that theyare not undergoing mass loss, properties similar to those of the redclump giants. Stars with subtypes R4 - R9 tend to be cooler and havesimilar luminosity to the N-type carbon stars, as confirmed by theirposition in the (J-H, H-K) color-color diagram. The sample of earlyR-type stars selected from the Hipparcos Catalogue appears to beapproximately complete to magnitude K0 ~ 7, translating intoa completeness distance of 600 pc if all R stars had MK= -2(400 pc if MK= -1). With about 30 early R-type stars in thatvolume, they comprise about 0.04% (0.14% for MK= -1) of thered clump stars in the solar neighborhood. Identification with the redclump locates these stars at the helium core burning stage of stellarevolution, while the N stars are on the asymptotic giant branch, wherehelium shell burning occurs. The present analysis suggests that for asmall fraction of the helium core burning stars (far lower than thefraction of helium shell-burning stars), carbon produced in the interioris mixed to the atmosphere in sufficient quantities to form a carbonstar. Based on observations from the Hipparcos astrometric satelliteoperated by the European Space Agency (ESA 1997).
| The effective temperatures of carbon-rich stars
We evaluate effective temperatures of 390 carbon-rich stars. Theinterstellar extinction on their lines of sights was determined andcircumstellar contributions derived. The intrinsic (dereddened) spectralenergy distributions (SEDs) are classified into 14 photometric groups(HCi, CVj and SCV with i=0,5 and j=1,7). The newscale of effective temperatures proposed here is calibrated on the 54angular diameters (measured on 52 stars) available at present from lunaroccultations and interferometry. The brightness distribution on stellardiscs and its influence on diameter evaluations are discussed. Theeffective temperatures directly deduced from those diameters correlatewith the classification into photometric groups, despite the large errorbars on diameters. The main parameter of our photometric classificationis thus effective temperature. Our photometric < k right >1/2 coefficients are shown to be angular diameters on arelative scale for a given photometric group, (more precisely for agiven effective temperature). The angular diameters are consistent withthe photometric data previously shown to be consistent with the trueparallaxes from HIPPARCOS observations (Knapik, et al. \cite{knapik98},Sect. 6). Provisional effective temperatures, as constrained by asuccessful comparison of dereddened SEDs from observations to modelatmosphere predictions, are in good agreement with the values directlycalculated from the observed angular diameters and with those deducedfrom five selected intrinsic color indices. These three approaches wereused to calibrate a reference angular diameter Phi 0 and theassociated coefficient CT_eff. The effective temperatureproposed for each star is the arithmetic mean of two estimates, one(``bolometric'') from a reference integrated flux F0, theother (``spectral'') from calibrated color indices which arerepresentative of SED shapes. Effective temperatures for about 390carbon stars are provided on this new homogeneous scale, together withvalues for some stars classified with oxygen-type SEDs with a total of438 SEDs (410 stars) studied. Apparent bolometric magnitudes are given.Objects with strong infrared excesses and optically thick circumstellardust shells are discussed separately. The new effective temperaturescale is shown to be compatible and (statistically) consistent with thesample of direct values from the observed angular diameters. Theeffective temperatures are confirmed to be higher than the mean colortemperatures (from 140 to 440 K). They are in good agreement with thepublished estimates from the infrared flux method forTeff>= 3170 K, while an increasing discrepancy is observedtoward lower temperatures. As an illustration of the efficiency of thephotometric classification and effective temperature scale, the C/Oratios and the Merrill-Sanford (M-S) band intensities are investigated.It is shown that the maximum value, mean value and dispersion of C/Oincrease along the photometric CV-sequence, i.e. with decreasingeffective temperature. The M-S bands of SiC2 are shown tohave a transition from ``none'' to ``strong'' at Teff =~(2800+/- 150right ) K. Simultaneously, with decreasing effectivetemperature, the mean C/O ratio increases from 1.04 to 1.36, thetransition in SiC2 strength occurring while 1.07<= C/O<= 1.18. This research has made use of the Simbad database operatedat CDS, Strasbourg, France. Table 10 is only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)}or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/369/178
| General Catalog of Galactic Carbon Stars by C. B. Stephenson. Third Edition
The catalog is an updated and revised version of Stephenson's Catalogueof Galactic Cool Carbon Stars (2nd edition). It includes 6891 entries.For each star the following information is given: equatorial (2000.0)and galactic coordinates, blue, visual and infrared magnitudes, spectralclassification, references, designations in the most significantcatalogs and coordinate precision classes. The main catalog issupplemented by remarks containing information for which there was noplace in entries of the main part, as well as some occasional notesabout the peculiarities of specific stars.
| The Role of Binaries in the Carbon Stars Pheonomenon
Not Available
| Magellanic Cloud Periphery Carbon Stars. IV. The SMC
The kinematics of 150 carbon stars observed at moderate dispersion onthe periphery of the Small Magellanic Cloud are compared with themotions of neutral hydrogen and early-type stars in the intercloudregion. The distribution of radial velocities implies a configuration ofthese stars as a sheet inclined at 73°+/-4° to the plane of thesky. The near side, to the south, is dominated by a stellar component;to the north, the far side contains fewer carbon stars and is dominatedby the neutral gas. The upper velocity envelope of the stars is closelythe same as that of the gas. This configuration is shown to beconsistent with the known extension of the SMC along the line of sightand is attributed to a tidally induced disruption of the SMC thatoriginated in a close encounter with the LMC some 0.3 to 0.4 Gyr ago.The dearth of gas on the near side of the sheet is attributed toablation processes akin to those inferred in 1996 by Weiner &Williams to collisional excitation of the leading edges of MagellanicStream clouds. Comparison with the 1989 kinematic data of Hardy,Suntzeff, & Azzopardi and Maurice, Martin, & Bouchet and the1986 and 1988 data of Mathewson et al. leaves little doubt that forcesother than gravity play a role in the dynamics of the H I.
| Quantitative analysis of carbon isotopic ratios in carbon stars. III. 26 J-type carbon stars including 5 silicate carbon stars
We present the result of a quantitative analysis of (12C/({13)) C}ratios in 26 J-type carbon stars. The (12C/({13)) C} ratios aredetermined from lines of the CN red system around 8000 Angstroms, usingthe iso-intensity method and line-blanketed model atmospheres. Theaverage of (12C/({13)) C}\ ratios in the 26 stars is 4.7 +/- 2.8(standard deviation). All the stars studied, except for two stars, have(12C/({13)) C}\ ratios smaller than 10. (12C/({13)) C}\ ratios as low as1 ~ 2, which are lower than the value at the equilibrium of theCN-cycle, are found for a significant fraction of our sample, suggestingthe operation of non-equilibrium nuclear processes. For several starspreviously analyzed by other authors, our result shows fair agreement.The serious disagreement of (12C/({13)) C}\ ratios, which we reportedfor N-type carbon stars in our preceding paper, is not found for J-typecarbon stars. Five silicate carbon stars in our sample show no peculiar(12C/({13)) C} ratios among the stars studied in the present work. Thisresult implies that the mechanism responsible for low (12C/({13)) C}\ratios in silicate carbon stars might be the same with that operating inother J-type carbon stars. In other words, (12C/({13)) C}\ ratios insilicate carbon stars have turned out to give few clues to identify themechanism responsible for their formation.
| Dust extinction and intrinsic SEDs of carbon-rich stars. II. The hot carbon stars
The present work is an extension of a recent study by Knapik &Bergeat (\cite{knapik}, henceforth called Paper I) of the spectralenergy distributions (SEDs) of about 300 cool carbon-rich variables andof the interstellar extinction observed on their line of sights. Themethods were originally developed for Semi-Regular (SR) and Irregular(L)-variables. Shortly, this is a kind of a pair method making usesimultaneously of the whole SED from UV to IR. Our approach is appliedhere to the galactic carbon-rich giants with bluer SEDs, namely the hotcarbon (HC) stars, including many ``constant'' stars and a minority ofvariables: AC Her a RV Tau star, the R Coronae Borealis (RCB) stars andothers. Some HdC (i.e. carbon-rich hydrogen deficient stars) and Ba IIstars are also considered. The total number of studied HC stars amountsto about 140. With few exceptions, the colour excesses for interstellarextinction are found in good agreement with the field values from mapspublished in the literature, taking into account the approximatedistances to our stars from HIPPARCOS data (\cite{esa}, henceforthcalled ESA) or binarity. We propose a classification scheme with sixphotometric groups (or boxes: HC0 to HC5) from the bluest to the reddestSEDs. Oxygen-rich SEDs earlier than HC0, are attributed to the hotteststars (AC Her, most RCB-variables and a few others). Previous findingsare confirmed of a junction between oxygen-rich and carbon-rich SEDs atspectral type G. The latest (HC5) group is immediately close to theearliest one in Paper I, namely CV1. The sequence of groups then goesregularly from HC0 to CV6. Substantial infrared excesses with respect toour solutions are found in HD 100764 a HC1 carbon star, AC Her a G0g RVTau star, and the RCB stars classified in either HC or oxygen-groups.The colour excesses at maximum light can usually be attributed tointerstellar reddening, with neutral circumstellar (CS) reddening (largegrains) or no CS extinction at all on the line of sight (non sphericalgeometry) as possible explanations. The latter model (disc or patchydistribution through successive puffs) is favoured. Two RCB variablesfor which we exploit SEDs on a rising branch (V CrA) or minimum light(RS Tel), show CS laws, respectively a selective extinction compatiblewith small grains and an extinction partly neutral indicative of largegrains on the line of sight. This research has made use of the Simbaddatabase operated at CDS, Strasbourg, France.}\fnmsep\thanks{Partiallybased on data from the ESA HIPPARCOS astrometrysatellite}\fnmsep\thanks{Tables~3 and 4 are only available in electronicform at the CDS via anonymous ftp 130.79.128.5
| First Byurakan Spectral Sky Survey. Stars of late spectral types. ‑11° ≤ δ ≤ ‑7° belt
A 10th list of late-type M and C stars found on plates of the FirstByurakan Spectral Sky Survey in the ‑ 11° ≤ δ ≤‑ 7° belt with an area of about 1070 deg2 is given.The list contains data on 169 red stars, 117 of which were found for thefirst time: 8 are new C stars, 3 are Cstar candidates, 104 are M stars,1 is either an M or an S star, and 1 object on the survey plate cannotbe classified. Of the 117 objects, 47 are unidentified IRAS sources. Astatistical analysis of the objects that are and are not identified withIRAS sources shows that the identified stars are, with a highprobability, brighter and have relatively more massive envelopes. Twostars were found to have fairly large brightness variability (with anamplitude of at least 6m.O). Gasdust shells are assumed toexist around nine of the IRAS sources. The equatorial coordinates,spectral types, and stellar magnitudes, determined on Palomar E maps,are given for the selected objects.
| The APM survey for cool carbon stars in the Galactic halo. I
A byproduct of the APM high-redshift quasar survey was the discovery ofseveral distant (20-100 kpc) N-type carbon stars at high galacticlatitude. Following on from this, we have started a systematic all-skysurvey at galactic latitudes /b/ greater than 30 deg to find furtherexamples of these rare objects, and we report here on the results fromthe first season of follow-up spectroscopy. Faint, high-latitude carbon(FHLC) giants make excellent probes of the kinematic structure of theouter Galactic halo. Therefore, in addition to detailedspectrophotometry covering a wide wavelength range, we have obtainedhigh-resolution (about 1 A) spectra centered on the CN bands at about8000 A, and have derived accurate radial velocities for the known FHLCstars. From the initial phase of our survey covering about 6500 sq deg,we find a surface density of faint N-type carbon stars in the halo ofabout 1 per 200 sq deg, roughly a factor of 4 less than the surfacedensity of CH-type carbon stars in the halo. Intermediate-age, N-typecarbon stars seem unlikely to have formed in the halo in isolation fromother star-forming regions, and one possibility that we areinvestigating is that they either arise from the disruption of tidallycaptured dwarf satellite galaxies or are a manifestation of thelong-sought optical component of the Magellanic Stream.
| Carbon Stars
Absolute magnitudes are estimated for carbon stars of various subtypesin the Hipparcos catalogue and as found in the Magellanic Clouds.Stellar radii fall within the limits of 2.4-4.7 AU. The chemicalcomposition of carbon stars indicates that the C-N stars show nearlysolar C/H, N/H, and ^12C/^13C ratios. This indicates that much of the Cand N in our Galaxy came from mass-losing carbon stars. Special carbonstars such as the C-R, C-H, and dC stars are described. Mass loss fromasymptotic giant branch (AGB) carbon stars, at rates up to several x10^-5 M{solar} year^-1, contributes about half of the total mass returnto the interstellar medium. R stars do not lose mass and may becarbon-rich red giants. The mass loss rates for Miras are about 10 timeshigher than for SRb and Lb stars, whose properties are similar enough toshow that they are likely to belong to the same population. Thedistribution of carbon star mass loss rates peaks at about 10^-7M{solar} year^-1, close to the rate of growth of the core mass anddemonstrative of the close relationship between mass loss and evolution.Infrared spectroscopy shows that dust mixtures can occur. Detachedshells are seen around some stars; they appear to form on the timescales of the helium shell flashes and to be a normal occurrence incarbon star evolution.
| 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
| Kinematics of carbon stars in the outer regions of the Small Magellanic Cloud
We present a radial velocity survey of a sample of the field populationof carbon stars in the outer parts of the Small Magellanic Cloud (SMC).This first set of results includes radial velocities for 71 carbonstars, with an individual precision of +/- 2-5 km/s. The meanheliocentric velocity of the stars (excluding one very high velocitystar) is 149.3+/-3.0 km/s with a velocity dispersion of 25.2 +/- 2.1km/s. These values drop to 145.5+/-2.7 km/s and 20.6+/-1.9 km/srespectively, if we exclude the stars belonging to the Outer Wing. Thevelocity distribution does not show the multiple peaks seen in somesamples of Population I objects. The mass of the SMC as inferred fromthe above velocity dispersion (without the outer Wing stars) is ~=1.2~10^9M_{\odot}. Tables 1a and 1b are available in electronic form atthe CDS via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/abstract.html
| The R Stars: Carbon Stars of a Different Kind
After $\sim$16 years of radial-velocity observations of a sample of 22R-type carbon stars, no evidence for binary motion has been detected inany of them. This is surprising considering that approximately 20\% ofnormal late-type giants are spectroscopic binaries, and the fraction isclose to 100\% in barium, CH, and subgiant/dwarf CH and barium stars. Itis suggested, therefore, that a process that has caused the mixing ofcarbon to the surface of these stars cannot act in a wide binary system.Possibly, the R stars were once all binaries, but with separations thatwould not allow them to evolve completely up the giant and asymptoticgiant branchs without coalescing. This coalescence may be the agentwhich causes carbon produced in the helium-core flash to be mixedoutwards to a region where convection zones can bring it to the surfaceof the star. (SECTION: Stars)
| A Moderate-Resolution Spectral Atlas of Carbon Stars: R, J, N, CH, and Barium Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJS..105..419B&db_key=AST
| A New Version of the Catalog of CH and Related Stars (CH95 Catalog)
A new version of the catalog of CH and related stars contains 244 fieldstars and 17 globular cluster stars. Here a list of these stars withtheir coordinates, their positions in the HR diagram and somestatistical diagrams is presented. The catalog will soon be available inthe printed and computerized versions.
| Classification of Population II Stars in the Vilnius Photometric System. I. Methods
The methods used for classification of Population II stars in theVilnius photometric system are described. An extensive set of standardswith known astrophysical parameters compiled from the literature sourcesis given. These standard stars are classified in the Vilnius photometricsystem using the methods described. The accuracy of classification isevaluated by a comparison of the astrophysical parameters derived fromthe Vilnius photometric system with those estimated from spectroscopicstudies as well as from photometric data in other systems. For dwarfsand subdwarfs, we find a satisfactory agreement between our reddeningsand those estimated in the uvbyscriptstyle beta system. The standarddeviation of [Fe/H] deter mined in the Vilnius system is about 0.2 dex.The absolute magnitude for dwarfs and subdwarfs is estimated with anaccuracy of scriptstyle <=0.5 mag.
| 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.
| Revised MK spectral classification of the red carbon stars
The spectral classification of the red carbon stars has been broughtinto the revised MK system by combining some of the features of the oldR, N, and C classifications, as modified by Yamashita, and addingnumerical abundance indices. The new types are intended to (1) definethe population to which the star belongs, (2) allow quick interpolationbetween the detailed atmospheric analyses of individual stars, and (3)indicate the differences between carbon stars in different parts of ourgalaxy, and in other galaxies. It is the flexibility of the notation,allowing the incorporation of improved criteria, that should make thenew system useful.
| CH stars in the Large Magellanic Cloud and in our Galaxy
Infrared JHK photometry is given for all the proposed LMC CH stars inthe list of Hartwick and Cowley (43 stars). Their luminosities range upto M(bol) of -6 or brighter, making them the most massive carbon starsin the LMC. However, the kinematic discussion of Hartwick and Cowleysuggests an age of a few Gyr for them. They may thus be the products ofbinary mergers, i.e. evolutionary products of blue stragglers of anintermediate-age population. Some analogous stars in the halo of theGalaxy may have evolved from globular cluster type blue stragglers.
| 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.
| Detached cold dust shell around the early R star (warm carbon star) HD 100764
The existence of a dust shell and warm dust near HD 100764 aredetermined from IRAS observations of early R stars, and theramifications of the findings are discussed. The mass of the dust shellis calculated to be 0.510 to the -4th solar mass, and the shell isconsidered to be an oxygen-rich silicate dust shell. The dust shell istheorized to be the result of mass loss experienced by the star duringthe helium core flash, a mechanism which is extended to the shells ofJ-type carbon stars.
| Catalogue of CH and metal-deficient barium stars
Not Available
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הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
|
תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | לויתן |
| התרוממות ימנית: | 02h35m06.50s |
| סירוב: | -09°26'34.1" |
| גודל גלוי: | 8.136 |
| מרחק: | 223.714 פארסק |
| תנועה נכונה: | 1.9 |
| תנועה נכונה: | 12.6 |
| B-T magnitude: | 9.729 |
| V-T magnitude: | 8.268 |
קטלוגים וכינוים:
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INHABITED SKY
