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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
| Classification of Spectra from the Infrared Space Observatory PHT-S Database
We have classified over 1500 infrared spectra obtained with the PHT-Sspectrometer aboard the Infrared Space Observatory according to thesystem developed for the Short Wavelength Spectrometer (SWS) spectra byKraemer et al. The majority of these spectra contribute to subclassesthat are either underrepresented in the SWS spectral database or containsources that are too faint, such as M dwarfs, to have been observed byeither the SWS or the Infrared Astronomical Satellite Low ResolutionSpectrometer. There is strong overall agreement about the chemistry ofobjects observed with both instruments. Discrepancies can usually betraced to the different wavelength ranges and sensitivities of theinstruments. Finally, a large subset of the observations (~=250 spectra)exhibit a featureless, red continuum that is consistent with emissionfrom zodiacal dust and suggest directions for further analysis of thisserendipitous measurement of the zodiacal background.Based on observations with the Infrared Space Observatory (ISO), aEuropean Space Agency (ESA) project with instruments funded by ESAMember States (especially the Principle Investigator countries: France,Germany, Netherlands, and United Kingdom) and with the participation ofthe Institute of Space and Astronautical Science (ISAS) and the NationalAeronautics and Space Administration (NASA).
| On the distance to the Chamaeleon I and II associations
Constraints on the distances to the dark clouds Chamaeleon I and II areinvestigated in detail. A compilation of photometric data, spectraltypes and absolute magnitudes for field stars towards each cloud ispresented, and results are used to examine the distribution of reddeningwith distance along each line of sight. The distances to starsassociated with reflection nebulae in each cloud are examined in detail.On the basis of these results, we deduce the most probable distance ofCha I to be 160+/-15pc, and that of Cha II to be 178+/-18pc. Anexamination of the mean fluxes of T Tauri stars in each cloud providesindependent evidence to suggest that Cha II is significantly moredistant than Cha I. Both clouds appear to be embedded in a macroscopicsheet-like structure extending over much of the Chamaeleon-Musca-Cruxregion. The Chamaeleon III and DC\ts 300.2--16.9 clouds are probablypart of the same structure, with probable distances ~ 140--160pc.
| Optical polarimetry, high--resolution spectroscopy and IR analysis of the Chamaeleon I dark cloud
We present optical polarimetry and high resolution spectroscopy of asample of stars toward the Chamaeleon I dark cloud. We use ourpolarimetry which includes 33 stars to study the wavelength dependenceof the degree and position angle of polarization. From fits to thenormalized wavelength dependence of interstellar polarization, we deriveestimates of lambdaMax ranging from 4500 \AA to 6700 \AA, andPMax ranging from 3 to 8%. The values of lambdaMaxwere found to be well correlated with the IRAS 100 micron intensity,while PMax was found to increase with E_{B-V}. Highresolution spectra of the Ca II, CH, and CH^{+} lines were obtained for10 stars, which show two components of Ca II in absorption at 3.0
| A Study of the Chamaeleon-I Dark Cloud and T-Association - Part Six - Interstellar Polarization Grain Alignment and Magnetic Field
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994MNRAS.268....1W&db_key=AST
| A study of the Chamaeleon I dark cloud and T-association. III - Near-infrared photometry of IRAS-selected field stars
Results of a program of ground-based near-infrared (JHKL) photometry arepresented for 28 IRAS-selected sources in Chamaeleon I unassociated withpreviously known members of the pre-main-sequence population.Ground-based data are combined with IRAS results (including those fromthe Serendipitous Survey data base) to investigate the nature andevolutionary status of the sample. A search for highly reddenedbackground stars was unsuccessful, but four previously unrecognizedyoung embedded stars were identified of which one (11057 - 7706) maystill be in the accretion phase. Serendipitous Survey data have alsobeen extracted for opically selected members of the T-association, andIRAS identifications for several which do not appear in the Point SourceCatalog are reported. The total number of young stars in Chamaeleon Idetected as point sources by IRAS is now 36.
| A study of the Chamaeleon dark cloud and T-association. I - Extinction, distance and membership
The results of an observing program to investigate the nature and degreeof reddening of a number of stars in the field towards the dark cloudand T-association in Chamaeleon are presented. The observations compriseoptical (UBVRI) and infrared (JHK) photometry, and optical spectroscopy.New and previously published data are combined to assess membershipcriteria for 110 stars, and separate catalogues of association membersand field stars are presented. Optical identifications are listed for 27IRAS point sources in the region. The reddening/distance relation forfield stars indicates a distance to the cloud of 140 + or - 12 pc. Thisresult confirms that the extinction law is anomalous towards some starsin the cloud, notably the embedded A0 ZAMS star HD 97300, with values ofup to 5.5 for the ratio of total-to-selective extinction. A comparisonof 21-cm data with the reddening of background field stars indicatesthat the ratio N(H I)/E(B-V) is significantly less than the interstellarmean, indicating that most of the hydrogen in the cloud is molecular.
| Further observations of magnitude with a coarse grating
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1952MNRAS.112..665W&db_key=AST
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Kaméleon |
| Rektaszcenzió: | 11h19m03.80s |
| Deklináció: | -75°49'29.6" |
| Vizuális fényesség: | 7.413 |
| Távolság: | 561.798 parszek |
| RA sajátmozgás: | -3.7 |
| Dec sajátmozgás: | -5.7 |
| B-T magnitude: | 9.676 |
| V-T magnitude: | 7.6 |
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