Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca, and Ti
Context. The formation and evolution of the Galactic bulge and itsrelationship with the other Galactic populations is still poorlyunderstood. Aims: To establish the chemical differences andsimilarities between the bulge and other stellar populations, weperformed an elemental abundance analysis of ?- (O, Mg, Si, Ca,and Ti) and Z-odd (Na and Al) elements of red giant stars in the bulgeas well as of local thin disk, thick disk and halo giants. Methods: We use high-resolution optical spectra of 25 bulge giants inBaade's window and 55 comparison giants (4 halo, 29 thin disk and 22thick disk giants) in the solar neighborhood. All stars have similarstellar parameters but cover a broad range in metallicity (-1.5 <[Fe/H] < +0.5). A standard 1D local thermodynamic equilibriumanalysis using both Kurucz and MARCS models yielded the abundances of O,Na, Mg, Al, Si, Ca, Ti and Fe. Our homogeneous and differential analysisof the Galactic stellar populations ensured that systematic errors wereminimized. Results: We confirm the well-established differencesfor [?/Fe] at a given metallicity between the local thin and thickdisks. For all the elements investigated, we find no chemicaldistinction between the bulge and the local thick disk, in agreementwith our previous study of C, N and O but in contrast to other groupsrelying on literature values for nearby disk dwarf stars. For -1.5 <[Fe/H] < -0.3 exactly the same trend is followed by both the bulgeand thick disk stars, with a star-to-star scatter of only 0.03 dex.Furthermore, both populations share the location of the knee in the[?/Fe] vs. [Fe/H] diagram. It still remains to be confirmed thatthe local thick disk extends to super-solar metallicities as is the casefor the bulge. These are the most stringent constraints to date on thechemical similarity of these stellar populations. Conclusions:Our findings suggest that the bulge and local thick disk starsexperienced similar formation timescales, star formation rates andinitial mass functions, confirming thus the main outcomes of ourprevious homogeneous analysis of [O/Fe] from infrared spectra for nearlythe same sample. The identical ?-enhancements of thick disk andbulge stars may reflect a rapid chemical evolution taking place beforethe bulge and thick disk structures we see today were formed, or it mayreflect Galactic orbital migration of inner disk/bulge stars resultingin stars in the solar neighborhood with thick-disk kinematics.Tables 8-15 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/513/A35
| Chemical similarities between Galactic bulge and local thick disk red giant stars
Context: The evolution of the Milky Way bulge and its relationship withthe other Galactic populations is still poorly understood. The bulge hasbeen suggested to be either a merger-driven classical bulge or theproduct of a dynamical instability of the inner disk. Aims: To probethe star formation history, the initial mass function and stellarnucleosynthesis of the bulge, we performed an elemental abundanceanalysis of bulge red giant stars. We also completed an identical studyof local thin disk, thick disk and halo giants to establish the chemicaldifferences and similarities between the various populations. Methods:High-resolution infrared spectra of 19 bulge giants and 49 comparisongiants in the solar neighborhood were acquired with Gemini/Phoenix. Allstars have similar stellar parameters but cover a broad range inmetallicity. A standard 1D local thermodynamic equilibrium analysisyielded the abundances of C, N, O and Fe. A homogeneous and differentialanalysis of the bulge, halo, thin disk and thick disk stars ensured thatsystematic errors were minimized. Results: We confirm thewell-established differences for [O/Fe] (at a given metallicity) betweenthe local thin and thick disks. For the elements investigated, we findno chemical distinction between the bulge and the local thick disk,which is in contrast to previous studies relying on literature valuesfor disk dwarf stars in the solar neighborhood. Conclusions: Ourfindings suggest that the bulge and local thick disk experiencedsimilar, but not necessarily shared, chemical evolution histories. Weargue that their formation timescales, star formation rates and initialmass functions were similar.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.
| Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalog
We present refined coordinates and proper-motion data for the highproper-motion (HPM) stars in the Luyten Half-Second (LHS) catalog. Thepositional uncertainty in the original Luyten catalog is typicallygreater than 10" and is often greater than 30". We have used the digitalscans of the POSS I and POSS II plates to derive more accurate positionsand proper motions of the objects. Out of the 4470 candidates in the LHScatalog, 4323 objects were manually reidentified in the POSS I and POSSII scans. A small fraction of the stars were not found because of thelack of finder charts and digitized POSS II scans. The uncertainties inthe revised positions are typically ~2" but can be as high as ~8" in afew cases, which is a large improvement over the original data.Cross-correlation with the Tycho-2 and Hipparcos catalogs yielded 819candidates (with mR<~12). For these brighter sources, theposition and proper-motion data were replaced with the more accurateTycho-2/Hipparcos data. In total, we have revised proper-motionmeasurements and coordinates for 4040 stars and revised coordinates for4330 stars. The electronic version of the paper5 contains the updated information on all 4470stars in the LHS catalog.
| Catalogue of [Fe/H] determinations for FGK stars: 2001 edition
The catalogue presented here is a compilation of published atmosphericparameters (Teff, log g, [Fe/H]) obtained from highresolution, high signal-to-noise spectroscopic observations. This newedition has changed compared to the five previous versions. It is nowrestricted to intermediate and low mass stars (F, G and K stars). Itcontains 6354 determinations of (Teff, log g, [Fe/H]) for3356 stars, including 909 stars in 79 stellar systems. The literature iscomplete between January 1980 and December 2000 and includes 378references. The catalogue is made up of two tables, one for field starsand one for stars in galactic associations, open and globular clustersand external galaxies. The catalogue is distributed through the CDSdatabase. Access to the catalogue with cross-identification to othersets of data is also possible with VizieR (Ochsenbein et al.\cite{och00}). The catalogue (Tables 1 and 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/373/159 and VizieRhttp://vizier.u-strasbg.fr/.
| 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
| Lithium in population I subgiants
We present a lithium survey for a sample of 91 Pop. I stars. JHKLphotometry was also obtained for 61 stars in the sample. Besides Liabundances, [Fe/H] values were derived. Thanks to Hipparcos parallaxes,we could infer absolute V magnitudes for our sample stars and were ableto place them on the color-magnitude diagram, which allowed us toconstrain their evolutionary status. Masses and ages were derived formost of the stars by comparison with evolutionary tracks. The sample wasoriginally selected so to include class IV stars later thanspectral-type F0, but, based on the location on the color-magnitudediagram, we found a posteriori that a fraction of the stars (about 20%)are either main sequence stars or evolved giants. As it is the case fordwarfs and giants, a large spread in lithium abundance is present amongthe subgiants in our sample. As expected, the average lithium decreasesas the stars evolve along the subgiant branch; however, there is not aone-to-one relationship between the position on the color-magnitudediagram and lithium abundance, and the observed dispersion is onlypartially explainable as due to a dispersion in mass, metallicity, andage. In particular, a dispersion in lithium is seen among slightlyevolved subgiants with masses close to solar but in the sameevolutionary stage as the G2 IV star beta Hyi. The comparison of thebeta Hyi-like sample with a sample of non evolved solar-like starsindeed suggests that beta Hyi has most likely evolved from a mainsequence Li-rich star, rather than from a Li-poor star (like the Sun)that has dredged-up previously stored lithium. Our sample includesseveral stars that have completed the first-dredge up lithium dilution,but that have not yet evolved to the evolutionary point whereextra-mixing in the giant phase is thought to occur. A large number ofthem have Li abundances considerably below the theoretical predictionsof first dredge-up dilution. We confirm that this is due to the factthat the progenitors of these stars are most likely stars that havedepleted lithium while on the main sequence; the fraction of post-dredgeup Li rich/poor stars, in fact, is consistent with the observeddistribution of Li abundances among stars that have just left the mainsequence. The signature of the second mixing (or RGB extra-mixing)episode is evident in the log n(Li) vs. B-V and log n(Li) vs. M_boldistributions of the stars in the sample; it seems however that theextra-mixing occurs at luminosities lower than predicted by the modelsof Charbonnel (1994). Finally, a few evolved giants are found thatshould have passed the second mixing episode, but that do not show signsof it. At least half of them are spectroscopic binaries. Based onobservations carried out at the European Southern Observatory, La Silla,Chile
| Astrometric positions of stars with high proper motions in the Southern Hemisphere
Several stars with large proper motions, cited by W.J. Luyten, wereincluded in the preliminary programme for the HIPPARCOS mission. Whenperforming preparatory measurements of plates, difficulties wereencountered in identifying certain of these stars when relying only onpublished coordinates. We have taken advantage of this work whichrelates to the southern sky in order to determine the astrometricposition of the greatest possible number of these objects, even forthose which were not included in the programme. Catalogue 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/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.
| 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
| The general catalogue of trigonometric [stellar] paralaxes
Not Available
| Longterm Photometry of Variables at ESO - Part Two - the Second Data Catalogue 1986-1990
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102...79S&db_key=AST
| 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.
| Long-term photometry of variables at ESO. I - The first data catalogue (1982-1986)
This paper presents the catalog of photometric data in the Stromgrensystem obtained during the first four years (October 1982 - September1986) of the Long-Term Photometry of Variables (LTPV) program at ESO.The data are available in computer-readable form.
| Four-color UVBY and H-beta photometry of high-velocity and metal-poor stars. I - The catalogue of observations
A catalog of four-color uvby and H-beta photometry for 711 high-velocityand metal-poor stars is given. The selection of the stars and theobserving and reduction techniques used to obtain these data arediscussed. The photometry has been transformed closely onto the standarduvby-beta system. The errors of the data have been estimated using bothinternal and external comparisons. The data are uniform over the sky;that is, there are no significant north-south differences. For the largemajority of stars the mean errors of V, m1, c1, and beta are less than +or - 0.008 mag, and the error of b-y is less than + or - 0.005 mag.Values of V, b-y and beta and rough photometric classifications aregiven for 63 red and/or evolved stars that fall outside the range of thephotometric transformations.
| Luminosities, abundances, and motions of stars brighter than visual magnitude 15.1 and annual proper motions larger than one-half arcsecond
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987AJ.....93..393E&db_key=AST
| Chromosphere emission in late main sequence stars of different masses and ages
Results on observations of emission components in the H and K lines ofCa II and in the h and k lines of Mg II of main sequence late typestars, belonging to the young Hyades and Coma clusters and the oldmoving groups, Zeta Her, epsilon Ind, sigma Pup, and Arcturus arepresented. An approach to obtain integrated emission fluxes of Mg IIlines from IUE low resolution spectra of solar and late type MS stars isproposed. From a preliminary analysis of the Ca II and Mg II emissionluminosity, the relation L(chrom) alpha mass upsilon is found to bevalid at least for young cluster stars, with upsilon = 4.34 for theHyades. A probable dependence of the chromospheric emission luminosityfrom the metallic abundance in the old disk population stars isdiscussed.
| Magnesium isotopes in moderately metal-poor stars
High resolution Reticon spectra of MgH (A2Pi - X2Sigma +) (0,0) and(1,1) lines between 5134-5137 A are used to determine the relativeabundances of magnesium isotopes in halo stars. Spectrum synthesiscalculations are applied to the 24 halo G and K observed stars withmetal abundances in the Fe/H abundance ratio range of -1.5 to 0.0.Values close to solar ratios Mg-24:Mg-25:Mg-26 = 79:10:11 are generallyfound. The odd-even effect is only present to a small extent, thepredictions from purely explosive conditions are not met and therefore aproduction of neutrons probably during hydrostatic shell carbon burningmust be important.
| Erratum - Errors or Omissions in Star-Identifications in the General Catalogue of Trigonometric Stellar Parallaxes
Not Available
| Some Cross-Reference Lists for the Catalog of Possible Nearby Stars
Not Available
| Possible nearby stars brighter than tenth magnitude
Basic data are compiled for 447 stars brighter than 10th visualmagnitude which may be within 25 pc of the sun and are missing from boththe Gliese (1969) and the Woolley et al. (1970) catalogs of nearbystars. The list includes 245 stars with photometric parallaxes, 17 starswith trigonometric parallaxes, and nine stars with dynamical parallaxes,all of which parallaxes are at least 0.040 arcsec, as well as 176 likelycandidates. The stars are grouped into six categories according to thereliability of absolute-magnitude estimates and ranked within each groupon the basis of calculated distance. The distance estimates incorporatea kinematic correction to the photometric parallaxes which is based onthe size of a star's proper motion. A list of stars brighter than 10thmag which appear in the Gliese but not in the Woolley et al. catalog isalso provided to facilitate cross-reference with existing catalogs ofnearby stars.
| Intermediate-band photometry of late-type stars. VIII - Nonvariable stars in the halo population near the sun
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979ApJ...229..158E&db_key=AST
| Kinematical and orbital properties for selected southern high-velocity stars
Using the model of the Galaxy presented by Eggen, Lynden-Bell, andSandage (1962), plane galactic orbits have been calculated for severalsouthern high-velocity stars which possess parallax, proper motion, andradial velocity data. Extensive lists of both raw and computed data forthese stars are included. Published values of U-B and B-V for some ofthese stars were used in plots of each of the orbital parameters versusU-B, B-V, or the ultraviolet excess. Also, a comparison is made betweenthe H-R diagrams for the southern high-velocity star group and that ofM3, a globular cluster, and again for M67, an old open cluster. Thehigh-velocity star group is found to resemble an old open cluster morethan a globular cluster.
| The Luminosities of Late-Type Stars of Differing Metal Abundance
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...177..665J&db_key=AST
| The ζ Herculis, σ Puppis, ∈ Indi, and η Cephei Groups of Old Disk Population Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971PASP...83..251E&db_key=AST
| Stellar kinematics and evolution
Not Available
| Radial velocities and three-colour photometry of 166 southern stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1965MNRAS.131...95P&db_key=AST
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Муха |
| Прямое восхождение: | 12h23m13.90s |
| Склонение: | -67°37'53.6" |
| Видимая звёздная величина: | 6.368 |
| Собственное движение RA: | -745 |
| Собственное движение Dec: | 252.5 |
| B-T magnitude: | 7.481 |
| V-T magnitude: | 6.46 |
Каталоги и обозначения:
|
