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A catalog of bright calibrator stars for 200-m baseline near-infrared stellar interferometry
We present in this paper a catalog of reference stars suitable forcalibrating infrared interferometric observations. In the K band,visibilities can be calibrated with a precision of 1% on baselines up to200 meters for the whole sky, and up to 300 meters for some part of thesky. This work, extending to longer baselines a previous catalogcompiled by Bordé et al. (2002, A&A, 393, 183), isparticularl y well adapted to hectometric-class interferometers such asthe Very Large Telescope Interferometer (VLTI, Glindemann et al. 2003,Proc. SPIE, 4838, 89) or the CHARA array (ten Brummelaar et al. 2003,Proc. SPIE, 4838, 69) when one is observing well-resolved, high-surfacebrightness objects (K 8). We use the absolute spectro-photometriccalibration method introduced by Cohen et al. (1999, AJ, 117, 1864) toderive the angular diameters of our new set of 948 G8-M0 calibratorstars extracted from the IRAS, 2MASS and MSX catalogs. Angular stellardiameters range from 0.6 mas to 1.8 mas (median is 1.1 mas) with amedian precision of 1.35%. For both the northern and southernhemispheres, the closest calibrator star is always less than 10°away.
| CHARM2: An updated Catalog of High Angular Resolution Measurements
We present an update of the Catalog of High Angular ResolutionMeasurements (CHARM, Richichi & Percheron \cite{CHARM}, A&A,386, 492), which includes results available until July 2004. CHARM2 is acompilation of direct measurements by high angular resolution methods,as well as indirect estimates of stellar diameters. Its main goal is toprovide a reference list of sources which can be used for calibrationand verification observations with long-baseline optical and near-IRinterferometers. Single and binary stars are included, as are complexobjects from circumstellar shells to extragalactic sources. The presentupdate provides an increase of almost a factor of two over the previousedition. Additionally, it includes several corrections and improvements,as well as a cross-check with the valuable public release observationsof the ESO Very Large Telescope Interferometer (VLTI). A total of 8231entries for 3238 unique sources are now present in CHARM2. Thisrepresents an increase of a factor of 3.4 and 2.0, respectively, overthe contents of the previous version of CHARM.The catalog is 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/431/773
| An unusually massive stellar black hole in the Galaxy
The X-ray source known as GRS1915+105 belongs to a group dubbed`microquasars'. These objects are binary systems which sporadicallyeject matter at speeds that appear superluminal, as is the case for somequasars. GRS1915+105 is also one of only two known binary sourcesthought to contain a maximally spinning black hole. Determining thebasic parameters of GRS195+105, such as the masses of the components,will help us to understand jet formation in this system, as well asproviding links to other objects which exhibit jets. Using X-ray data,indirect methods have previously been used to infer a variety of massesfor the accreting compact object in the range 10-30 solar masses(Mȯ). Here we report a direct measurement of theorbital period and mass function of GRS1915+105, which allow us todeduce a mass of 14 +/- 4Mȯ for the black hole. Blackholes with masses >5-7Mȯ challenge theconventional picture of black-hole formation in binary systems. Based onthe mass estimate, we interpret the distinct X-ray variability ofGRS1915+105 as arising from instabilities in an accretion disk that isdominated by radiation pressure, and radiating near the Eddington limit(the point where radiation pressure supports matter against gravity).Also, the mass estimate constrains most models which relate observableX-ray properties to the spin of black holes in microquasars.
| Identification of the donor in GRS 1915+105
We report on medium-resolution H and K band spectroscopy of GRS 1915+105using the 8m VLT at ESO. We clearly identify absorption bandheads from^12CO/^13CO. Together with other features we classify the donor as a K-MIII star.
| 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
| Near infrared light variations of chemically peculiar stars. The SrCrEu stars
Twenty magnetic Chemically Peculiar (CP2) stars of the SrCrEu subgroupmostly brighter than the 7.5 visual magnitude have been investigated inthe near infrared at 1.25, 1.6 and 2.2 mu . The stars HD 3980, HD 24712,HD 49976, HD 83368, HD 96616, HD 98088, HD 118022, HD 125248, HD 148898,HD 203006, and HD 220825 have been found to be variable in the infraredwith the same period as the visible light, spectrum, and magnetic fieldvariations. HD 221760 is also variable with a period of 12.45 days,which has to be confirmed. The stars HD 72968, HD 111133, HD 126515, HD153882, and HD 164258 do show some hint of variability, although thedata are too few. Infrared variability has been detected for the firsttime in the stars HD 101065, and HD 206088, which have not yet beenconsidered as variable. No variability has been detected for the star HD137949 within a time scale of the order of ten days. Based onobservations collected at the European Southern Observatory, La SillaChile.
| 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.
| DDO Observations of Southern Stars
Not Available
| 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.
| Narrow-Band and Broad-Band Photometry of Red Stars. III. Southern Giants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...161..199E&db_key=AST
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Mikroszkóp |
| Rektaszcenzió: | 21h15m14.70s |
| Deklináció: | -40°30'23.0" |
| Vizuális fényesség: | 6.21 |
| Távolság: | 178.891 parszek |
| RA sajátmozgás: | 100.1 |
| Dec sajátmozgás: | 7.4 |
| B-T magnitude: | 7.676 |
| V-T magnitude: | 6.339 |
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