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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
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
| 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
| 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 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
| IRAS 12311-3509: a carbon star with SiC2 emission
The optical spectrum of the carbon star IRAS 12311-3509 is dominated bythe Merrill-Sanford emission bands of SiC2, by absorption andemission in the Swan system of C2, and by resonance emissionlines of neutral metals. The infrared energy distribution is flat from 1to 60μm. These observations are interpreted as arising from a starwith a cool dusty disc which is edge-on to the observer and obscuresdirect starlight. The infrared continuum is caused predominantly byabsorption of stellar light by dust in the disc and re-emission atlonger wavelengths. The optical stellar spectrum is seen by reflectionoff dusty material which lies out of the plane of the disc, and themolecular and atomic emission arises in the same geometry throughresonance fluorescence. The object has similarities to the J-silicatestars, but may have a carbon-rich rather than oxygen-rich disc. A fullspectroscopic assignment and discussion of the SiC2 bands andtheir intensities are given. Modelling of the rotational contours of the000 band yields a rotational temperature of 250K,indicating very cool gas.
| The Role of Binaries in the Carbon Stars Pheonomenon
Not Available
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| 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
| Baldone Schmidt Telescope Plate Archive and Catalogue
The article presents information on the archive and catalogue of theastrophotos taken with the Schmidt telescope of the Institute ofAstronomy of the University of Latvia (until July 1, 1997 --Radioastrophysical Observatory of the Latvian Academy of Sciences) inthe period 1967--1998. The archive and catalogue contain more than 22000direct and 2300 spectral photos of various sky regions. Information onthe types of photo materials and color filters used as well as on mostfrequently photographed sky fields or objects is given. The catalogue isavailable in a computer readable form at the Institute of Astronomy ofthe University of Latvia and at the Astrophysical Observatory in Baldone(Riekstukalns, Baldone, LV-2125, Latvia), e-mail: astra@latnet.lv.
| Infrared Spectroscopy of Faint High Galactic Latitude Carbon Stars
Carbon stars at high Galactic latitudes used to study the kinematics ofthe Galactic halo are difficult to distinguish from nearby dwarf carbon(dC) stars at intermediate spectral resolution. This paper presentsnear-infrared spectra of a sample of carbon stars that show that the COfirst-overtone bands are far weaker in the known dC stars than in giantsfor a given H-K color. This finding, along with the unusual location ofdC stars in the JHK color-color diagram, may be explained by the effectsof collision-induced absorption, which is predicted, in stars of lowmetallicity and high surface gravity, to greatly suppress molecularabsorption features in the near-infrared.
| 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)
| 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
| New infrared carbon stars in the IRAS point source catalog.
We present new results of a search for infrared carbon stars (IRCS)based on the combination of IRAS and near infrared colours. A sample of207 stars with IRAS colours that characterize IRCS is selected andmeasured in the $JHKL$ photometric bands. Using a [12 - 25] vs. K - Lcolour diagram, 20 new IRCS candidates are proposed. Medium resolutionspectra in the ~ 6000-9000 Angstrom range of 8 of these candidatesconfirm their carbon rich nature. In addition we propose a few starswith LRS class "4n" as oxygen--rich candidates, and a few stars with LRSclasses "0n" and "1n" as carbon-rich. Based on observations obtained atthe Observatoire de Haute Provence, France. Tables 2 and 3 are onlyavailable 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
| 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.
| Constraints on the Origin of Dwarf Carbon Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994ApJ...423..723G&db_key=AST
| Spectroscopic study of carbon stars with silicate features. 1: Observations
The results of an optical spectroscopic study of carbon stars withsilicate feature done at the Dominion Astrophysical Observatory (DAO) inVictoria in 1991 is presented. Four stars are confirmed to be C-13-richcarbon stars (J stars). Two stars are provisionally identified as Jstars. A preliminary spectral analysis is carried out. Two groups of Jstars were found in the IRAS color-color diagram. The 'red group'contains carbon stars with silicate emission feature which are good Jstar candidates; and the 'vertical strip group' contains standard Jstars which show weak or no SiC feature. It is suggested that thesources in the 'red group' represent the higher mass members of theasymptotic giant branch population. The enhancement of C-13 may beexplained by the envelope burning mechanism.
| Carbon stars at high Galactic latitude
Photometry and kinematics are presented for a sample of objective prismselected carbon stars toward the north and south Galactic poles.Distances are determined by fitting the infrared colors to a giantbranch. If these stars are like the carbon stars seen in dwarfspheroidal galaxies, the median distance of the sample is 28 kpc. Ifthey are more like the carbon stars found recently in the Galacticbulge, they may be only half as distant. The surface density of carbonstars as a function of distance is remarkably consistent with an R exp1/4 density profile for the Galactic halo. This density profile can betraced to about 15 scale radii and fills a volume similar to thatoccupied by globular clusters. The data yields an effective radius ofeither 7.0 or 3.5 kpc depending on choice of distance scale. Thevelocity dispersion of the sample is 96 + or - 12 km/s. A kinematicmodel in which vertical velocity dispersion is independent of heightabove the Galactic plane seems in best accord with the data.
| A general catalogue of cool carbon stars
Not Available
| Spectrophotometric investigation of carbon stars
Not Available
| The absolute spectrophotometry of carbon stars. VI. Abundance of carbon in the atmospheres.
Not Available
| Photoelectric photometry of carbon and barium stars in the Vilnius seven-color system and their color excesses
Not Available
| The ratios of color excesses and the R ratios in the UBV and the Vilnius photometric systems for carbon and barium stars
Not Available
| Spectrophotometry of carbon stars. III - Molecular absorption bands: Quantitative analysis
The C2, CN, SiC2, and CH molecular absorption bands of 56 carbon starsare analyzed quantitatively on the basis of the spectroscopicobservations reported by Ogansian et al. (1985); the results arepresented in tables and graphs. Features noted include a separation ofearly and late stars in the C2 Swan-system red/blue index diagram, aseparation of R and N stars in the (C-12)N/(C-13)N index diagram, and acorrelation between the 4976-A Merrill-Sanford band and the 5896/5890-ANa I doublet.
| An R star in the central bulge of the galaxy
A carbon star in the central bulge of the Galaxy is shown to be of lateR type, with strong C-13 features. The latter distinguish it from thetypical carbon stars of the upper AGB in Magellanic Cloud clusters ofintermediate age, in accordance with the absence of bright carbon starsin the Baade Window fields and the difficulty of producing carbon starsby the helium shell flash route in metal-rich stars of low mass.Unusually strong Na D 5890, 5896 lines support the supposition that itis metal-rich.
| The Spectrophotometry of Carbon Stars - Part Two
Not Available
| The Spectrophotometry of Carbon Stars - Part One
Not Available
| Spectrophotometry of cool carbon stars
Observations of 75 carbon stars have been made with the Indiana rapidspectrum scanner covering a wavelength range of 5000 A-7000 A at 30-Aresolution. The data have been used to form molecular indices for aquantitative measurement of the strength of the C2 Swan system and theshape of the CN red (6, 1) band sequence which is sensitive to theC-12/C-13 isotope ratio. The C2 strength is plotted against the strengthof CN and CO; the observed band strengths are found to behave as wouldbe expected from model-atmosphere calculations. Using C/O ratios fromKilston (1975) it is possible to calculate the observed CN/C2 ratio anddetermine photometric C/O ratios for 61 cool carbon stars. The CN red(6, 1) band photometry shows that only a few (25%) of cool carbon starshave C-12/C-13 isotope ratios significantly lower than the majority ofcool carbon stars.
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| Csillagkép: | Rák |
| Rektaszcenzió: | 09h13m50.08s |
| Deklináció: | +14°12'39.2" |
| Vizuális fényesség: | 8.581 |
| Távolság: | 1149.425 parszek |
| RA sajátmozgás: | -1 |
| Dec sajátmozgás: | -4.2 |
| B-T magnitude: | 10.686 |
| V-T magnitude: | 8.755 |
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