Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Catalogs of temperatures and [Fe/H] averages for evolved G and K stars
A catalog of mean values of [Fe/H] for evolved G and K stars isdescribed. The zero point for the catalog entries has been establishedby using differential analyses. Literature sources for those entries areincluded in the catalog. The mean values are given with rms errors andnumbers of degrees of freedom, and a simple example of the use of thesestatistical data is given. For a number of the stars with entries in thecatalog, temperatures have been determined. A separate catalogcontaining those data is briefly described. Catalog only available atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants
We present X-ray data for all late-type (A, F, G, K, M) giants andsupergiants (luminosity classes I to III-IV) listed in the Bright StarCatalogue that have been detected in the ROSAT all-sky survey.Altogether, our catalogue contains 450 entries of X-ray emitting evolvedlate-type stars, which corresponds to an average detection rate of about11.7 percent. The selection of the sample stars, the data analysis, thecriteria for an accepted match between star and X-ray source, and thedetermination of X-ray fluxes are described. Catalogue only available atCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Classification of Population II Stars in the Vilnius Photometric System. II. Results
The results of photometric classification of 848 true and suspectedPopulation II stars, some of which were found to belong to Population I,are presented. The stars were classified using a new calibrationdescribed in Paper I (Bartkevicius & Lazauskaite 1996). We combinethese results with our results from Paper I and discuss in greaterdetail the following groups of stars: UU Herculis-type stars and otherhigh-galactic-latitude supergiants, field red horizontal-branch stars,metal-deficient visual binaries, metal-deficient subgiants, stars fromthe Catalogue of Metal-deficient F--M Stars Classified Photometrically(MDPH; Bartkevicius 1993) and stars from one of the HIPPARCOS programs(Bartkevicius 1994a). It is confirmed that high galactic latitudesupergiants from the Bartaya (1979) catalog are giants or even dwarfs.Some stars, identified by Rose (1985) and Tautvaisiene (1996a) as fieldRHB stars, appear to be ordinary giants according to our classification.Some of the visual binaries studied can be considered as physical pairs.Quite a large fraction of stars from the MDPH catalog are found to havesolar metallicity. A number of new possible UU Herculis-type stars, RHBstars and metal-deficient subgiants are identified.
| 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
| Chemical Abundances for F and G Luminosity Class II Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.2425L&db_key=AST
| Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
| Photometry of Stars in the Field of ZZ Draconis
Not Available
| Photometry of Stars in the Field of the Mira XY Aquilae
Not Available
| Photometry of Stars in the Field of AV Cygni and DV Cygni
Not Available
| Sodium in weak G-band giants
Sodium abundances have been determined for eight weak G-band giantswhose atmospheres are greatly enriched with products of the CN-cyclingH-burning reactions. Systematic errors are minimized by comparing theweak G-band giants to a sample of similar but normal giants. If,further, Ca is selected as a reference element, model atmosphere-relatederrors should largely be removed. For the weak-G-band stars (Na/Ca) =0.16 +/- 0.01, which is just possibly greater than the result (Na/Ca) =0.10 /- 0.03 from the normal giants. This result demonstrates that theatmospheres of the weak G-band giants are not seriously contaminatedwith products of ON cycling.
| Evolved GK stars near the Sun. 2: The young disk population
From a sample of nearly 2000 GK giants a group of young disk stars withwell determined space motions has been selected. The zero point of theluminosity calibrations, both from the ultraviolet flux (modifiedStroemgren system) and that in the region of 4200 to 4900 A (DDOsystem), show a discontinuity of about a half magnitude at the border ofthe young disk and old disk domains. The population separation is basedon the space velocity components, which are also an age discriminant,with the population interface near 2 x 109 yr, based onmodels with convective overshoot at the core. This age corresponds togiant masses near 1.7 solar mass, near the critical mass separating theyoung stars that do not burn helium in degenerate cores from older starsthat do. Ten percent of both populations show CN anomalies in that thederived value of P(Fe/H) from CN (Cm) and fromFe(M1) differ by more than 0.1 dex and the weak and strong CNstars occur equally in the old disk but the weak CN stars predominate inthe young disk. Peculiar stars, where flux distortions affect theluminosity calibrations, are of the CH+(Ba II) and CH-(weak G band)variety and represent less than 1% of the stars in both populations. Theyoung disk giants are restricted to ages greater than about109 yr, because younger stars are bright giants orsupergiants (luminosity class 2 or 1), and younger than about 2 x109 yr, because the old disk-young disk boundary occurs near1.7 solar mass. The distribution of heavy element abundances, P(Fe/H),for young disk giants is both more limited in range (+/- 0.4 dex) and isskewed toward higher abundances, compared with the nearly normaldistribution for old disk giants. The distribution of (U,V) velocityvectors gives (U,V,W) and their dispersions = (+17.6 +/- 18.4, -14.8 +/-8.4, -6.9 +/- 13.0) and (+3.6 +/- 38.4, -20.7 +/- 27.5, -6.7 +/-17.3)km/s for young and old disk giants, respectively.
| The southern Vilnius photometric system. I - Transformation to the standard system
This paper is the first in a series on the extension of the Vilniusphotometric system to the southern hemisphere. Observations of a commonset of 73 stars measured in both hemispheres are described and ananalysis of the differences is given.
| Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
| Classification of Population II supergiants and related stars in the Vilnius system
The results of photometric classification in the Vilnius system of 117Population II supergiants, suspected supergiants, and related stars aregiven. Their photometric spectral types, intrinsic color indices (Y-V)0,color excesses E(Y-V), metallicities Fe/H, and absolute magnitudes MVare determined. It is shown that the system allows us to detect the UUHerculis-type supergiants photometrically. The analyzed SRd star samplefalls into two groups of metallicity and luminosity. Our photometricclassification assigns luminosity classes from III to V to 37 F-K starswith /b/ greater than 16 deg classified by Bartaya (1979) from objectiveprism spectra as supergiants.
| Photometry of F-K type bright giants and supergiants. I - Intermediate band and H-Beta observations
Over 1500 observations of 560 bright giants and supergiants of types F-Kare presented and compared to the observations by Gray and Olsen (1991).The present results include intermediate-band which is slightlydifferent from the Stromgren data by Gray and Olsen due to a differentwidth for the v filter. A systematic difference in m(1) - M(1) withdecreasing temperature is noted in the two H-Beta data sets, and thecorrelations are defined.
| Ca II H and K filter photometry on the UVBY system. I - The standard system
A fifth filter (fwhm = 90 A) centered on Ca II H and K has beendeveloped for use with the standard uvby system. The filter, called Ca,is designed primarily for applications to metal-poor dwarfs and redgiants, regions where the uvby metallicity index, m(l), loses somesensitivity. An index, hk, is defined by replacing v in m(l) by Ca. Theeffects of interstellar extinction on the index are modeled anddemonstrated to be modest and relatively insensitive to spectral type.Observations of V, (b-y), and hk for 163 primary standards are detailedand transformed to the standard V and (b-y) system. A qualitativeanalysis using only the primary standards indicates that hk is moresensitive than m(l) over the regions of interest by about a factor of 3.
| An uvby-beta catalogue of F0-K0 supergiant stars brighter than V = 6.5
Photoelectric uvby-beta photometry is reported for 111 F0-K0 supergiantstars which are brighter than V = 6.5 mag and located betweendeclination of -15 and +61 deg. A comparison with previous observationsis made. A few stars which are suspected to present light variations arementioned.
| 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.
| CA II H emission line cores of late-type dwarfs - Variability measurements and velocity field diagnostics
High-resolution spectra of Alpha Cen B, Xi Boo A, 70 Oph A, and EpsilonInd obtained using the Coude Echelle Spectrometer and the 1.4-m CoudeAuxiliary Telescope of ESO are analyzed. Variations in the normalizedfluxes for the four dwarfs are described. Position and intensitymeasurements of the Ca II H features are examined. The use of thespectra for chromospheric velocity field diagnostics is discussed. Thedata reveal that it is possible to separate the effects of plages fromthose due to vertical velocity fields; in some stars the H core samplesnet upflow and in other net downflow; the layer sampled by the H3feature shows a velocity close to that defined by the photospheric restframe; and the H2V/H2R asymmetry is useful as a linear measure of thechromospheric vertical velocity gradient.
| A search for duplicity in the weak G-band stars
The radial velocities of seven weak G-band stars have been monitored fora period of over two years. Velocity variations are seen in the knownspectroscopic binary HR 1023, from which the orbital solution isderived. Small-amplitude variations are present in the velocities of 37Com and HR 6791, and the other four stars have constant velocities.These results indicate that, unlike the Ba II stars which have beendiscovered recently to be all binaries, the weak G-band stars do nothave an unusually high incidence of duplicity. The origin of the weakG-band phenomenon must be sought after in a scenario of single-starevolution.
| Lithium in late-type giants. III - The weak G band giants
Li abundances are presented for nine different stars to demonstrate thatthe abundances are consistent with the cosmic value. The observationswere made with the coude telescope and echelle spectrometer on La Silla,covering the Li I 6707 A resonance doublet and the 800 A 2-0 band. Thesurvey included the HD stars 18636, 31274, 36552, 40402, 78146 and 82595and the HR stars 1299 and 4154, all Southern Hemisphere weak FraunhoferG band objects. Both Li-6 and Li-7 were detected in HR 1299. It issuggested that the Li detected in all the stars convected outwardquickly and survived, while C diffused inward and was converted to C-13and N-14. The Li abundances can be observed in both main sequence andred giant stars.
| Three-dimensional calssification of F-M type halo stars in the Vilnius photometric system
Not Available
| The lithium in weak G-band stars
Available data on Li abundance and CH band weakness in weak G-band starsindicates the existence of a linear relationship between Li and carbonabundance. Weak G-band stars with a high Li abundance are least depletedin C, and weak G-band stars with a relatively low Li abundance have avery low abundance of C. Li production seems to be a necessity after thestar leaves the main sequence and reaches the giant branch, probably byspallation reactions on the surface. Then mixing due to meridionalcirculation on the giant branch might bring out the CN-processedmaterial to the surface, at the same time destroying the surface Li.Thus, both C and Li abundances are depleted together.
| The lithium abundance in weak-G band stars
Lithium abundances are derived for ten weak-G band giants. The stars arefound to have at least normal lithium abundances, and may have enhancedlithium relative to normal giants of similar temperature. Also, broadlines found in the G5 giant HR 1023 can be interpreted as rotation witha variable radial velocity of amplitude 17 + or - 5 km/sec. Possibleinterpretations of these results are discussed.
| The strength of the 2.3 MU CO band in weak-G-band stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..660H&db_key=AST
| MK classifications for F-and G-type stars. 3.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..682H&db_key=AST
| Photoelektrische Photometrie von Shell-Sternen
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...15..311H&db_key=AST
| Photoelectric radial velocities. V. 69 southern HR stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.155..449G&db_key=AST
| UBV-Helligkeiten von acht Sternpaaren am Äquator
Not Available
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Змея |
| Прямое восхождение: | 18h06m07.40s |
| Склонение: | -00°26'48.0" |
| Видимая звёздная величина: | 6.34 |
| Расстояние: | 155.521 парсек |
| Собственное движение RA: | -22 |
| Собственное движение Dec: | -12.8 |
| B-T magnitude: | 7.622 |
| V-T magnitude: | 6.466 |
Каталоги и обозначения:
|
