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Публикации по объекту
Chemical Abundances of the Secondary Star in the Black Hole X-Ray Binary XTE J1118+480
Following recent abundance measurements of Mg, Al, Ca, Fe, and Ni in theblack hole X-ray binary XTE J1118+480 using medium-resolution Keck IIESI spectra of the secondary star, we perform a detailed abundanceanalysis including the abundances of Si and Ti. These elementabundances, which are higher than solar, indicate that the black hole inthis system formed in a supernova event, whose nucleosynthetic productscould pollute the atmosphere of the secondary star, providing clues tothe possible formation region of the system, either Galactic halo, thickdisk, or thin disk. We explore a grid of explosion models with differentHe core masses, metallicities, and geometries. Metal-poor modelsassociated with a formation scenario in the Galactic halo provideunacceptable fits to the observed abundances, allowing us to reject ahalo origin for this X-ray binary. The thick-disk scenario producesbetter fits, although they require substantial fallback and veryefficient mixing processes between the inner layers of the explosion andthe ejecta, making an origin in the thick disk quite unlikely. The bestagreement between model predictions and the observed abundances isobtained for metal-rich progenitor models. In particular,non-spherically symmetric models are able to explain, without strongassumptions of extensive fallback and mixing, the observed abundances.Moreover, asymmetric mass ejection in a supernova explosion couldaccount for the required impulse necessary to launch the system from itsformation region in the Galactic thin disk to its current halo orbit.
| The usage of Strömgren photometry in studies of local group dwarf spheroidal galaxies. Application to Draco: a new catalogue of Draco members and a study of the metallicity distribution function and radial gradients
Aims.In this paper we demonstrate how Strömgren uvby photometry canbe efficiently used to: 1. identify red giant branch stars that aremembers in a dwarf spheroidal galaxy; 2. derive age-independentmetallicities for the same stars and quantify the associated errors. Methods: Strömgren uvby photometry in a 11 × 22 arcmin fieldcentered on the Draco dwarf spheroidal galaxy was obtained using theIsaac Newton Telescope on La Palma. Members of the Draco dSph galaxywere identified using the surface gravity sensitive c1 indexwhich discriminates between red giant and dwarf stars. Thus enabling usto distinguish the (red giant branch) members of the dwarf spheroidalgalaxy from the foreground dwarf stars in our galaxy. The method isevaluated through a comparison of our membership list with membershipclassifications in the literature based on radial velocities and propermotions. The metallicity sensitive m1 index was used toderive individual and age-independent metallicities for the members ofthe Draco dSph galaxy. The derived metallicities are compared to studiesbased on high resolution spectroscopy and the agreement is found to bevery good. Results: We present metallicities for 169 members of the redgiant branch in the Draco dwarf spheroidal galaxy (the largest sample todate). The metallicity distribution function for the Draco dSph galaxyshows a mean [Fe/H] = -1.74 dex with a spread of 0.24 dex. Thecorrelation between metallicity and colour for the stars on the redgiant branch is consistent with a dominant old, and coeval population.There is a possible spatial population gradient over the field with themost metal-rich stars being more centrally concentrated than themetal-poor stars.Based on observations made with the Isaac Newton Telescope, operated onthe Island of La Palma by the Isaac Newton Group in the SpanishObservatorio del Roque de los Muchachos of the Instituto de Astrofisicade Canarias. Guest User, Canadian Astronomy Data Centre, which isoperated by the Herzberg Institute of Astrophysics, National ResearchCouncil of Canada. Full Tables 2 and 6 are only available athttp://www.aanda.org
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| 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.
| A doppler map and mass-ration constraint for the black-hole x-ray nova ophiuchi 1977.
We have reanalyzed Keck observations of Nova Oph 1977 to extend the workdone by Filippenko et al. (1997), who recently determined a massfunction f(M_x) = 4.86 +/- 0.13 Msun for the compact object.We constrain the rotational broadening, upsilon sin i <= 79 km s(-1), at the 90% confidence level, which gives a mass ratio q <= 0.053.The K-type companion star of Nova Oph 1977 contributes 28-37% of thelight at red wavelengths. The abnormal Li 1 lambda 6708 absorption linefrom the companion star is not detected (EW < 0.12 Angstroms), incontrast to four other X-ray binaries. An Hα Doppler image of thesystem shows emission from the companion star in addition to theaccretion disk.
| Photometry of Stars with Large Proper Motion
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.2300W&db_key=AST
| The Mass Ratio and the Disk Image of the X-Ray Nova GS 2000+25
Keck observations of the black hole candidate GS 2000+25 in quiescencehave recently been used by Filippenko, Matheson, and Barth to determinea mass function f(M_x) = 4.97 +/- 0.10 solar mass for the compactobject. Our reanalysis of the data confirms this result (5.01 +/- 0.12solar mass). We estimate a mass ratio of q = M_c/M_x = 0.042 +/- 0.012from the rotational broadening of the companion star, v sin i = 86 +/- 8km s^-1. From q and the companion star's radial velocity K_c, we derivethe mass of the compact object M_x = (5.44 +/- 0.15) sin^-3 i solar massand the mass of the companion star M_c = (0.23 +/- 0.02) sin^-3 i solarmass. Constraints on the inclination (75 degrees > i > 47 degrees)lead to 6.04 < M_x < 13.9 and 0.26 < M_c < 0.59 (1-sigma) insolar mass units. We determine a spectral type of K3-K6 for thecompanion star, which contributes more than 72% of the light at redwavelengths (94% +/- 5% for K5 V). Our analysis shows that the companionis an undermassive star, slightly evolved but not a subgiant. Consistentwith the work of Filippenko et al. we detect Li I lambda-6708 absorption(equivalent width 150 +/- 85 mA) in the spectrum of the companion. ADoppler image of the system shows evidence for a bright spot whichcontributes 10% of the emission-line flux density, and arises in therange 0.3-0.6 R_L1 of the accretion disk, where L1 is the innerLagrangian point. Along the trajectory of the gas stream, the velocitiesare initially ballistic and gradually become Keplerian. (SECTION: Stars)
| A Black Hole in the X-Ray Nova GS 2000+25
We have obtained 13 moderate-resolution (~2.5 A) spectra of the GalacticX-ray nova GS 2000+25 in quiescence with the W. M. Keck 10 m telescope.Cross-correlation with the spectra of late-type dwarfs (especiallyK2--K7) yields excellent radial velocities for the secondary star. Theorbital period is consistent with that previously obtained fromphotometry (~8.3 hr). A semiamplitude of 518.4 +/- 3.5 km s-1 is found,~25% smaller than the outer disk velocity implied by the double-peaked Halpha emission line ( Delta v/2 ~ 700 km s-1). The derived mass functionis 4.97 +/- 0.10 M?, the second highest known for any low-massX-ray binary. Being considerably above the conventional limiting massfor a neutron star (~3.2 M?), it strongly suggests that the compactprimary is a black hole. Plausible mass estimates based on M2 = 0.4--0.7M? and i = 67.dg5--80 deg are M1 = 5.9--7.5 M?. Under theassumption that the radial velocity curve of the centroid of the H alphaemission line represents the true motion of the black hole, we formallyfind q = M2/M1 = 0.050 +/- 0.026.
| 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.
| The general catalogue of trigonometric [stellar] paralaxes
Not Available
| 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.
| UBV photoelectric catalogue (1986). II - Analysis
The UBV photoelectric data of the stars presenting several entries inthe 1986 edition of the UBV catalog have been systematicallyintercompared, and this paper presents a discussion of the stars forwhich discrepancies larger than 0.2 mag were found. Thirty-six probablyvariable stars have been detected, among which 18 are Be stars. Sixtyfurther stars present differences in the V magnitude larger than 0.2mag. Sixteen stars already appear in the NSV catalog. Although manyproblems are probably due to poor observations, new (eclipsing) variablestars may be found in this sample. Complete disagreement is foundbetween the values published from two independent sources in 34 cases. Afirst analysis of the quality of the UBV data shows that 65 percent ofthe differences in the V magnitude and in U-B color, for respectively11,500 and 7200 stars with two sources of data, are smaller than 0.04.The scatter on the B-V index appears to be smaller, since the samepercentage reaches 79 percent.
| UBV Photoelectric Photometry Catalogue (1986). III Errors and Problems on DM and HD Stars
Not Available
| 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
| Catalog of proper-motion stars. III - Stars brighter than visual magnitude 15.1, south of declination +30 deg, and with annual proper motion between 0.5 and 0.7 arcsec
A catalog of (VRI) photometry for the some one thousand stars withannual proper motion between 0.5 and 0.7 arcsec, brighter than visualmagnitude 15.1, and south of declination +30 deg is presented. Theavailable proper-motion and radial-velocity data are also summarized.
| G. P. Kuiper's spectral classifications of proper-motion stars
Spectral classifications are listed for over 3200 stars, mainly of largeproper motion, observed and classified by Kuiper during the years1937-1944 at the Yerkes and McDonald Observatories. While Kuiper himselfpublished many of his types, and while improved classifications are nowavailable for many of these stars, much of value remains. For many ofthe objects, no other spectral data exist.
| 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.
| Dwarf K and M stars in the southern hemisphere.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..486U&db_key=AST
| Luminosities, Temperatures, and Kinematics of K-Type Dwarfs
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...22..389E&db_key=AST
| Lowell proper motions IV : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory
Not Available
| Photoelectric observations of red dwarf stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956AJ.....61..213M&db_key=AST
| Dwarf M Stars Found Spectrophotometrically. Second List.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1946ApJ...104..234V&db_key=AST
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Дева |
| Прямое восхождение: | 13h47m23.45s |
| Склонение: | -06°08'12.8" |
| Видимая звёздная величина: | 10.364 |
| Расстояние: | 42.517 парсек |
| Собственное движение RA: | -339.1 |
| Собственное движение Dec: | -575.8 |
| B-T magnitude: | 11.36 |
| V-T magnitude: | 10.447 |
Каталоги и обозначения:
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