Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
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.
| GPM1 - a catalog of absolute proper motions of stars with respect to galaxies
The description of the first version of the General Compiled Catalogueof Absolute Proper Motions (GPM1) for a sample of HIPPARCOS stars,derived with respect to galaxies within the plan called Catalogue ofFaint Stars (KSZ, Deutch 1952), is presented. The principal aim of theGPM1 construction was to provide absolute proper motions of stars todetermine the rotation of the HIPPARCOS system. The GPM1 cataloguecontains 977 HIPPARCOS Input Catalogue stars with V magnitudes $5^m -11^m in 180 fields north of -25 degrees of declination. The accuracy ofthe proper motions is 8 mas/yr (milliarcseconds per year). Comparison ofproper motions of GPM1 with those of the PPM and ACRS was performed andanalyzed with respect to systematic errors caused by spurious rotationof the FK5 system. The standard errors show that the rotation may bedetermined with an accuracy better than 1 mas/yr. Catalog is onlyavailable in electronic form at the CDS via anonymous ftpcdsarc.u-strasbg.fr or ftp 130.79.128.5.
| GPM - compiled catalogue of absolute proper motions of stars in selected areas of sky with galaxies.
Not Available
| The integrated spectra of M32 and of 47 Tuc: A comparative study at high spectral resolution
Integrated spectra have been obtained for the elliptical galaxy M32 andfor the 'metal-rich' Galactic globular cluster 47 Tuc. The spectra coverthe wavelength interval lambda lambda 3800-4400 A at a resolution of 2.5A full width at half maximum (FWHM) and S/N ratio of approximately100:1. Similar data have been acquired for a library of 191 individualstars, and, to support the 47 Tuc observations, integrated spectra offour additional metal-rich Galactic globular clusters have beenobtained. These observations are used to compare in detail theintegrated spectra of M32 (the most extensively studied ellipticalgalaxy) and 47 Tuc (the best-studied metal-rich Galactic globularcluster). Although M32 and 47 Tuc have similar optical broadband colorsand overall spectral types, when viewed at 2.5 A resolution spectranumerous subtle differences between their integrated are clearlyvisible. A system of 13 spectral indices, many of them originallydefined in Rose (1984), has been used to quantify these differences.Altogether twelve diagnostic diagrams are presented to illustrate themanner in which the integrated spectrum of M32 differs from that of 47Tuc. These diagrams are used to place several strong constraints on thestellar populations in these two systems.
| 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.
| Common proper motion stars in the AGK 3
A search was made of common-proper-motion (CPM) systems among AGK 3stars. The selection of physical systems was based upon the ratiobetween the angular separation (rho) and the proper motion (mu); the CPMstars found are presented in two tables. Table I lists systems withrho/mu less than 1000 years. It contains 326 entries, and the proportionof optical pairs is estimated to be 1 percent. Table II lists systemswith rho/mu in the range 1000 to 3500 years; it contains 113 systems,but only 60 percent of them are physical. Nevertheless, these systemsoften have separations larger than 10,000 AU and are the mostinteresting for the study of the tail of the distribution function ofthe semimajor axes.
| Binaries among bright stars - Systems with evolved primary components and their relation to the properties of main-sequence binaries
A study on the distribution of Delta m of main-sequence visual binaries(VBs), derived using previously published data, suggests that thesubgiants and early-type giants are one magnitude brighter than whenthey were dwarfs. The progenitors of late-type giants are on average F1dwarfs, while those of VBs with Delta m of less than 8, 5, or 3magnitudes are on average A7, A2, and B9.5 dwarfs, respectively. Theintrinsic logarithmic distribution of the semimajor axis (a) is derivedfrom dwarf, subgiant, and early-type giant VBs considered together, andis found to be constant for a of greater than 30 AU. Takingspectroscopic binaries into account, the proportion of single starsamong all stellar systems is found to be at the most 23 percent.
| Red horizontal-branch stars in the galactic disk
A quantitative, three-dimensional spectral classification systemdeveloped by Rose (1984), which uses 2.5-A resolution spectra in theblue, has been used to identify a class of red horizontal branch (RHB)stars in the Galactic disk that are similar to those in the 'metal rich'globular cluster M 71. The RHB are denoted as evolved stars by their SrII 4077 line, and are distinguished from post-main sequence starsevolving through the same region of the HR diagram on the basis of theunique appearance of their CN 3883 and 4216 A bands. The RHB starsconsitute at least 5 percent of the entire giant branch population ofthe disk.
| Spectral anomalies in the Hyades and Pleiades and in field stars with active chromospheres
Widened photographic image-tube spectra at 50 A/mm dispersion have beenobtained for a large number of late-type field dwarfs and giants withwell-determined atmospheric parameters and for 35 Hyades dwarfs and 31Pleiades dwarfs. The observations and data analysis are discussed, and asummary of the quantitative spectral classification system is given.This system is used to compare the Hyades and Pleiades with field stars.The cluster stars are found to exhibit several anomalies with respect tothe field stars which are not readily explained either by abundance orsurface gravity peculiarities, or by the presence of cool starspots onthe strong Ca II emission stars, or by cool companions. It is proposedthat active regions on stars with strong Ca II emission reversals haveseriously affected many of the principal spectral lines.
| An investigation of the consistency of the calibrations of the UVBY beta and GNKMF photometric systems.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....15..161O&db_key=AST
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
| Csillagkép: | Szűz |
| Rektaszcenzió: | 13h35m34.68s |
| Deklináció: | +10°13'25.4" |
| Vizuális fényesség: | 8.942 |
| Távolság: | 91.241 parszek |
| RA sajátmozgás: | 89.8 |
| Dec sajátmozgás: | -52.8 |
| B-T magnitude: | 9.459 |
| V-T magnitude: | 8.985 |
Katalógusok és elnevezések:
|
