Ýçindekiler
Görüntüler
Resim Yükleyin
DSS Images Other Images
Ýlgili Makaleler
Mass-loss properties of S-stars on the AGB
We have used a detailed non-LTE radiative transfer code to model newAPEX CO(J = 3 → 2) data, and existing CO radio line data, on asample of 40 AGB S-stars. The derived mass-loss-rate distribution has amedian value of 2 × 10-7~Mȯyr-1, and resembles values obtained for similar samples ofM-stars and carbon stars. Possibly, there is a scarcity ofhigh-mass-loss-rate (≥10-5~Mȯyr-1) S-stars. The distribution of envelope gas expansionvelocities is similar to that of the M-stars, the median is 7.5 kms-1, while the carbon stars, in general, have higher gasexpansion velocities. The mass-loss rate correlates well with the gasexpansion velocity, in accordance with results for M-stars and carbonstars.
| Really Cool Stars and the Star Formation History at the Galactic Center
We present λ/Δλ=550-1200 near-infrared H and Kspectra for a magnitude-limited sample of 79 asymptotic giant branch andcool supergiant stars in the central ~5 pc (diameter) of the Galaxy. Weuse a set of similar spectra obtained for solar neighborhood stars withknown Teff and Mbol that is in the same range asthe Galactic center (GC) sample to derive Teff andMbol for the GC sample. We then construct the H-R diagram forthe GC sample. Using an automated maximum likelihood routine, we derivea coarse star formation history of the GC. We find that (1) roughly 75%of the stars formed in the central few parsecs are older than 5 Gyr; (2)the star formation rate (SFR) is variable over time, with a roughly 4times higher SFR in the last 100 Myr compared to the average SFR; (3)our model can match dynamical limits on the total mass of stars formedonly by limiting the initial mass function to masses above 0.7Msolar (this could be a signature of mass segregation or ofthe bias toward massive star formation from the unique star formationconditions in the GC); (4) blue supergiants account for 12% of the totalsample observed, and the ratio of red to blue supergiants is roughly1.5; and (5) models with isochrones with [Fe/H]=0.0 over all ages fitthe stars in our H-R diagram better than models with lower [Fe/H] in theoldest age bins, consistent with the finding of Ramírez et al.that stars with ages between 10 Myr and 1 Gyr have solar [Fe/H].
| Guilt by Association: The 13 Micron Dust Emission Feature and Its Correlation to Other Gas and Dust Features
A study of all full-scan spectra of optically thin oxygen-richcircumstellar dust shells in the database produced by the ShortWavelength Spectrometer on ISO reveals that the strength of severalinfrared spectral features correlates with the strength of the 13 μmdust feature. These correlated features include dust features at 19.8and 28.1 μm and the bands produced by warm carbon dioxide molecules(the strongest of which are at 13.9, 15.0, and 16.2 μm). The databasedoes not provide any evidence for a correlation of the 13 μm featurewith a dust feature at 32 μm, and it is more likely that a weakemission feature at 16.8 μm arises from carbon dioxide gas ratherthan dust. The correlated dust features at 13, 20, and 28 μm tend tobe stronger with respect to the total dust emission in semiregular andirregular variables associated with the asymptotic giant branch than inMira variables or supergiants. This family of dust features also tendsto be stronger in systems with lower infrared excesses and thus lowermass-loss rates. We hypothesize that the dust features arise fromcrystalline forms of alumina (13 μm) and silicates (20 and 28 μm).Based on observations with the ISO, a European Space Agency (ESA)project with instruments funded by ESA member states (especially thePrincipal Investigator countries: France, Germany, the Netherlands, andthe United Kingdom) and with the participation of the Institute of Spaceand Astronautical Science (ISAS) and the National Aeronautics and SpaceAdministration (NASA).
| Infrared Colors and Variability of Evolved Stars from COBE DIRBE Data
For a complete 12 μm flux-limited sample of 207 IRAS sources(F12>=150 Jy, |b|>=5deg), the majority ofwhich are AGB stars (~87%), we have extracted light curves in seveninfrared bands between 1.25 and 60 μm using the database of theDiffuse Infrared Background Experiment (DIRBE) instrument on the CosmicBackground Explorer (COBE) satellite. Using previous infrared surveys,we filtered these light curves to remove data points affected by nearbycompanions and obtained time-averaged flux densities and infraredcolors, as well as estimates of their variability at each wavelength. Inthe time-averaged DIRBE color-color plots, we find clear segregation ofsemiregulars, Mira variables, carbon stars, OH/IR stars, and red giantswithout circumstellar dust (i.e., V-[12]<5) and with little or novisual variation (ΔV<0.1 mag). The DIRBE 1.25-25 μm colorsbecome progressively redder and the variability in the DIRBE databaseincreases along the oxygen-rich sequence nondusty slightly varying redgiants-->SRb/Lb-->SRa-->Mira-->OH/IR and the carbon-richSRb/Lb-->Mira sequence. This supports previous assertions that theseare evolutionary sequences involving the continued production andejection of dust. The carbon stars are redder than their oxygen-richcounterparts for the same variability type, except in theF12/F25 ratio, where they are bluer. Of the 28sources in the sample not previous noted to be variable, 18 are clearlyvariable in the DIRBE data, with amplitudes of variation of ~0.9 mag at4.9 μm and ~0.6 mag at 12 μm, consistent with them being verydusty Mira-like variables. We also present individual DIRBE light curvesof a few selected stars. The DIRBE light curves of the semiregularvariable L2 Pup are particularly remarkable. The maxima at1.25, 2.2, and 3.5 μm occur 10-20 days before those at 4.9 and 12μm, and, at 4.9 and 12 μm, another maximum is seen between the twonear-infrared maxima.
| Mass loss and rotational CO emission from Asymptotic Giant Branch stars
We present submillimeter observations of rotational transitions ofcarbon monoxide from J = 2 -> 1 up to 7 -> 6 for a sample ofAsymptotic Giant Branch stars and red supergiants. It is the first timethat the high transitions J=6 -> 5 and 7 -> 6 are included in sucha study. With line radiative transfer calculations, we aim to determinethe mass-loss history of these stars by fitting the CO line intensities.We find that the observed line intensities of the high transitions,including the J=4 -> 3 transition, are significantly lower than thepredicted values. We conclude that the physical structure of the outflowof Asymptotic Giant Branch stars is more complex than previouslythought. In order to understand the observed line intensities andprofiles, a physical structure with a variable mass-loss rate and/or agradient in stochastic gas velocity is required. A case study of the AGBstar WX Psc is performed. We find that the CO linestrengths may be explained by variations in mass-loss on time scalessimilar to those observed in the separated arc-like structures observedaround post-AGB stars. In addition, a gradient in the stochasticvelocity may play a role. Until this has been sorted out fully, any massloss determinations based upon single CO lines will remain suspect.
| 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
| Near-infrared observations of candidate extrinsic S stars
Photometric observations in the near infrared for 161 S stars, including18 Tc-rich (intrinsic) stars, 19 Tc-deficient (extrinsic) ones and 124candidates for Tc-deficient S stars, are presented in this paper. Basedon some further investigations into the infrared properties of bothTc-rich and Tc-deficient S stars, 104 candidates are identified as verylikely Tc-deficient S stars. The large number of infrared-selectedTc-deficient S stars provides a convenient way to study the physicalproperties and the evolutionary status of this species of S stars.
| Periods of 25 Pulsating Red Giants
We report periods and amplitudes of 25 pulsating red giants: T Cet, EGAnd, AK Hya, TV UMa, GK Com, SW Vir, FH Vir, EV Vir, tau-4 Ser, AZ Dra,V973 Cyg, V1070 Cyg, and also HR 211, 284, 648, 2286, 2999, 3521, 4267,4483, 5331, 5352, 6543, 6815, and 7009, determined from AmericanAssociation of Variable Stars (AAVSO) photoelectric photometry over upto 5800 days.
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| On the Relations between Infrared Colors and Mass Loss Rates for S Stars
A relation between the infrared color K-[12] and the mass loss rate,dM/dt, is found for the intrinsic S stars. This relation isqualitatively similar to the ones for carbon stars and oxygen-rich Mirastars, but quantitatively different. It could be useful in the contextof the near infrared surveys, DENIS and 2MASS, which are in progress.Correlations between J-K and [12]-[25] indices and dM/dt are found to beloose for S stars.
| Polarimetry of 167 Cool Variable Stars: Data
Multicolor photoelectric polarimetry is presented for 167 stars, most ofwhich are variable stars. The observations constitute a data set thatfor some stars covers a time span of 35 yr. Complex variations are foundover time and wavelength and in both the amount of polarization and itsposition angle, providing constraints for understanding the polarizingenvironments in and around these cool stars.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
| On the Variability of K5-M Stars
I investigate the Hipparcos Satellite photometry of K5-M stars to seethe pattern of activity of these stars. A few stars for which furtherstudy is desirable are identified.
| Detection of the Cosmic Infrared Background at 2.2 and 3.5 Microns Using DIRBE Observations
We compare data from the Diffuse Infrared Background Experiment (DIRBE)on COBE to the model of the infrared sky provided by Wainscoat andcolleagues in 1992. The model is first compared with broadband K (2.2μm) star counts. Its success at K band lends credence to its physicalapproach, which is extrapolated to the L band (3.5 μm). We haveanalyzed the histograms of the pixel-by-pixel intensities in the 2.2 and3.5 μm maps from DIRBE after subtracting the zodiacal light. Theshape of these histograms agrees quite well with the histogram shapepredicted using the Wainscoat model of the infrared sky, but thepredicted histograms must be displaced by a constant intensity in orderto match the data. This shift is the cosmic infrared background, whichis 16.9+/-4.4 kJy sr-1 or 23.1+/-5.9 nW m-2sr-1 at 2.2 μm and 14.4+/-3.7 kJy sr-1 or12.4+/-3.2 nW m-2 sr-1 at 3.5 μm. Combining ournear-IR results with the far-IR background detected by Hauser andcolleagues in 1998 suggests that roughly half of the radiation producedby galaxies is absorbed by dust and reradiated in the far-IR.
| Dust features in the 10-mu m infrared spectra of oxygen-rich evolved stars
We have analyzed the 8-13.5 mu m UKIRT CGS3 spectra of 142 M-type starsincluding 80 oxygen-rich AGB stars and 62 red supergiants, with a viewto understanding the differences and similarities between the dustfeatures of these stars. We have classified the spectra into groupsaccording to the observed appearance of the infrared features. In eachcase the normalized continuum-subtracted spectrum has been compared tothose of the other stars to find similarities and form groups. The dustfeatures of the AGB stars are classified into six groups: broad AGB,where the feature extends from 8 mu m to about 12.5 mu m with littlestructure; broad+sil AGB, which consists of a broad feature with anemerging 9.7 mu m silicate bump; and four silicate AGB groups in which a``classic'' 9.7 mu m silicate feature gets progressively narrower.Likewise, the supergiant spectra have also been classified into groups,however these do not all coincide with the AGB star groups. In thesupergiant case we again have six groups: featureless, where there islittle or no emission above the continuum; broad Super, where thefeature extends from about 9 mu m to about 13 mu m; and four silicateSuper groups, which again show a progression towards the narrowest``classic'' 9.7 mu m silicate feature. We compare the mean spectrum foreach group, which yields two main results. Firstly, while the``classic'' silicate feature is essentially identical for both AGB starsand red supergiants, the broad features observed for these two stellartypes are quite different. We suggest that the dust in these twoenvironments follows different evolutionary paths, with the dust aroundMira stars, whose broad feature spectra can be fit by a combination ofalumina (Al2O3) and magnesium silicate,progressing from this composition to dust dominated by magnesiumsilicate only, while the dust around supergiants, whose broad featurecan be fit by a combination of Ca-Al-rich silicate andAl2O3, progresses from this initial composition toone eventually also dominated by magnesium silicate. The reason for thedifference in the respective broad features is not clear as yet, butcould be influenced by lower C/O ratios and chromospheric UV radiationfields in supergiant outflow environments. The second result concernsthe 12.5 - 13.0 mu m feature discovered in IRAS LRS spectra and widelyattributed to Al2O3. This feature is seenpredominantly in the spectra of semiregular variables, sometime in Mirasand only once (so far) in supergiant spectra. We argue that it isunlikely that this feature is due to Al2O3 or, ashas more recently been suggested, spinel(MgAl2O4), but could be associated with silicondioxide or highly polymerized silicates (not pyroxenes or olivines).
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The Henize sample of S stars. I. The technetium dichotomy
This paper is the first one in a series investigating the properties ofthe S stars belonging to the Henize sample (205 S stars with delta<-25(deg) and R<10.5) in order to derive the respective properties(like galactic distribution and relative frequencies) of intrinsic (i.e.genuine asymptotic giant branch) S stars and extrinsic (i.e. postmass-transfer binary) S stars. High-resolution (R=30 000 to 60 000)spectra covering the range lambda lambda4230 -4270 Angstroms have beenobtained for 76 S stars, 8 M stars and 2 symbiotic stars. The lambda4262Angstroms and lambda4238 Angstroms blends involving a Tc I line wereanalysed separately and yield consistent conclusions regarding thepresence or absence of technetium. Only one `transition' case (Hen 140 =HD 120179, a star where only weak lines of technetium are detectable) isfound in our sample. A resolution greater than R =30 000 is clearlyrequired in order to derive unambiguous conclusions concerning thepresence or absence of technetium. The Tc/no Tc dichotomy will becorrelated with radial velocity and photometric data in a forthcomingpaper. Based on observations carried out at the European SouthernObservatory (ESO, La Silla, Chile)
| On the Variability of S Stars as Observed by the Hipparcos
The Hipparcos photometry of S type stars shows that they are allvariable. The intrinsic S stars show a larger range of amplitudes thando the extrinsic S stars.
| The Infrared Spectral Classification of Oxygen-rich Dust Shells
This paper presents infrared spectral classifications for a flux-limitedsample of 635 optically identified oxygen-rich variables includingsupergiants and sources on the asymptotic giant branch (AGB). Severalclasses of spectra from oxygen-rich dust exist, and these can bearranged in a smoothly varying sequence of spectral shapes known as thesilicate dust sequence. Classification based on this sequence revealsseveral dependencies of the dust emission on the properties of thecentral star. Nearly all S stars show broad emission features fromalumina dust, while most of the supergiants exhibit classic featuresfrom amorphous silicate dust. Mira variables with symmetric light curvesgenerally show broad alumina emission, while those with more asymmetriclight curves show classic silicate emission. These differences may arisefrom differences in the photospheric C/O ratio.
| HIPPARCOS Period-Luminosity Relations for Mira and Semiregular variables
We present period-luminosity (P-L) diagrams for nearby Mira andsemiregular variables, selecting stars with parallaxes better than 20%and well-determined periods. Using K-band magnitudes, we find twowell-defined P-L sequences, one corresponding to the standard Mira P-Lrelation and the second shifted to shorter periods by a factor of about1.9. The second sequence contains only semiregular variables, while theMira sequence contains both Mira and semiregular variables. Severalsemiregular stars show double periods that are in agreement with bothrelations. The Whitelock evolutionary track is shown to fit the data,indicating that the semiregular variables are Mira progenitors. Thetransition between the two sequences may correspond to a change in thepulsation mode or to a change in the stellar structure. Large-amplitudepulsations that lead to the classical Mira classification occur mainlynear the tip of the local asymptotic giant branch luminosity function.
| CO observations and mass loss of MS- and S-stars
We present (12) CO J = 1-0 and 2-1 observations of 14 S-stars, andreport 6 new detections. Two stars were observed in the (13) CO J = 1-0and 2-1 lines, and one tentative 2-1 detection is reported. Acompilation is presented of all CO observations of S-stars. The stars inthis sample are separated into ``intrinsic'' and ``extrinsic'' S-stars,based on direct observation of the Technetium line, or infraredproperties. The dust mass loss rate per unit distance is derived fromIRAS 60 mu m data taking into the fact that for small mass loss ratesthe observed flux is an overestimate of the excess emission due to dust.The gas mass loss rate per unit distance is derived from CO data.Distances and luminosities are estimated, partly from hipparcos parallaxdata. The largest mass loss rate derived is that for W Aql with(0.8-2.0) x 10(-5) {Msun} yr(-1) , and the lowest is that foro Ori with <1.2 x 10(-9) {Msun} yr(-1) . The S-starswithout Tc have smaller mass loss rates, than those with Tc. Diagramsshowing mass loss rate, dust-to-gas ratio and expansion velocity versuspulsation period are presented, and compared to similar data for carbon-and oxygen-rich Miras. The S-Miras stand not out in any way from the C-or O-Miras in these diagrams. In the diagram with expansion velocityversus pulsation period, the S-SRs span the same range in velocity asthe S-Miras, but they have periods which are about a factor of 2.5shorter. This was previously noted for O-rich SRs. As in that case, themost straightforward explanantion is that the SRs among the S-starspulsate in a higher order pulsation mode. Based on data from the ESAhipparcos astrometry satellite.
| Infrared study of the two categories of S stars
Photometric observations of 20 Tc-deficient and 24 Tc-rich S stars inthe near infrared are presented in this paper. With the IRAS data,infrared two color diagrams, IRAS low-resolution spectra and energydistributions are discussed to summarize the way to segregate Tc-richstars from Tc-deficient ones.
| The HIPPARCOS Hertzsprung-Russell diagram of S stars: probing nucleosynthesis and dredge-up
HIPPARCOS trigonometrical parallaxes make it possible to compare thelocation of Tc-rich and Tc-poor S stars in the Hertzsprung-Russell (HR)diagram: Tc-rich S stars are found to be cooler and intrinsicallybrighter than Tc-poor S stars. The comparison with the Genevaevolutionary tracks reveals that the line marking the onset of thermalpulses on the asymptotic giant branch (AGB) matches well the observedlimit between Tc-poor and Tc-rich S stars. Tc-rich S stars are, asexpected, identified with thermally-pulsing AGB stars of low andintermediate masses, whereas Tc-poor S stars comprise mostly low-massstars (with the exception of 57 Peg) located either on the red giantbranch or on the early AGB. Like barium stars, Tc-poor S stars are knownto belong exclusively to binary systems, and their location in the HRdiagram is consistent with the average mass of 1.6+/-0.2 Msb ȯderived from their orbital mass-function distribution (Jorissen et al.1997, A&A, submitted). A comparison with the S stars identified inthe Magellanic Clouds and in the Fornax dwarf elliptical galaxy revealsthat they have luminosities similar to the galactic Tc-rich S stars.However, most of the surveys of S stars in the external systems did notreach the lower luminosities at which galactic Tc-poor S stars arefound. The deep Westerlund survey of carbon stars in the SMC uncovered afamily of faint carbon stars that may be the analogues of thelow-luminosity, galactic Tc-poor S stars. Based on data from theHIPPARCOS astrometry satellite
| 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.
| Aluminum Oxide and the Opacity of Oxygen-rich Circumstellar Dust in the 12--17 Micron Range
Amorphous alumina (Al2O3) was produced by a sol-gel technique in orderto make available its optical constants for possible astrophysicalapplications. Gradual annealing showed that the X-ray amorphousness ofalumina ended somewhere between 723 and 873 K. Above this transitionpoint, the structure changes into disordered gamma -Al2O3. At T >1273 K, crystalline alpha -Al2O3 (corundum) is formed. Mie calculationsshow that amorphous alumina exhibits a wide Al-O vibrational band,peaking at 11.5--11.8 mu m and having a steep "blue" and an extended"red" wing. It may be an important contributor to the continuous opacitybetween the silicate bands in oxygen-rich circumstellar envelopes,whereas it is ruled out for the explanation of the 13 mu m band. Anaverage 13 mu m band profile was derived from 51 IRAS low-resolutionspectra of bright Mira stars and semiregular variables. Its shape, whichis satisfactorily represented by a Lorentz profile, can be reproduced byMie calculations with the data of alpha -Al2O3, but not with those ofgamma -Al2O3. The calculations show that the 13 mu m band profile ofalpha -Al2O3 is sensitive to grain shape. If alpha -Al2O3 is theabsorber, a second band should be present at 21 mu m. A closecorrelation was found between the strengths of the 13 mu m band and the10 mu m silicate band. It suggests that the 13 mu m band carrier couldalso be somehow connected with silicate dust. Experimental argumentssupporting this attribution are presented.
| Proper motions, absolute magnitudes and spatial distribution of zirconium stars.
Not Available
| Accurate Positions Of Variable Stars Near The South Galactic Pole
Not Available
| The energy distribution in the visible spectrum for 27 class M giants and supergiants
Not Available
| 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.
| A catalogue of associations between IRAS sources and S stars.
Cross identifications between the General Catalogue of Galactic S Stars(GCGSS), the IRAS Point Source Catalogue (PSC), and the Guide StarCatalogue (GSC) are presented. The purpose of the present catalogue isi) to provide a clean sample of S stars with far-IR data, and ii) toprovide accurate GSC positions for S stars, superseding those listed inthe GCGSS. The IRAS colour-colour diagram and the galactic distributionof S stars associated with an IRAS source are presented. Several S starshaving extended images in at least one IRAS band have also beenidentified.
|
Yeni bir Makale Öner
Ýlgili Baðlantýlar
Yeni Bir Baðlantý Öner
sonraki gruplarýn üyesi:
|
Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Balina |
| Sað Açýklýk: | 00h21m46.30s |
| Yükselim: | -20°03'28.0" |
| Görünürdeki Parlaklýk: | 5.12 |
| Uzaklýk: | 237.53 parsek |
| özdevim Sað Açýklýk: | 63.3 |
| özdevim Yükselim: | -12.7 |
| B-T magnitude: | 7.813 |
| V-T magnitude: | 5.926 |
Kataloglar ve belirtme:
|
