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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
| CHARM: A Catalog of High Angular Resolution Measurements
The Catalog of High Angular Resolution Measurements (CHARM) includesmost of the measurements obtained by the techniques of lunaroccultations and long-baseline interferometry at visual and infraredwavelengths, which have appeared in the literature or have otherwisebeen made public until mid-2001. A total of 2432 measurements of 1625sources are included, along with extensive auxiliary information. Inparticular, visual and infrared photometry is included for almost allthe sources. This has been partly extracted from currently availablecatalogs, and partly obtained specifically for CHARM. The main aim is toprovide a compilation of sources which could be used as calibrators orfor science verification purposes by the new generation of largeground-based facilities such as the ESO Very Large Interferometer andthe Keck Interferometer. The Catalog is available in electronic form atthe 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/386/492, and from theauthors on CD-Rom.
| Angular diameter and effective temperature of a sample of 15M giants at 2.2μm from lunar occultation observations
High angular resolution measurements of a sample of 15M giants at2.2μm by the technique of lunar occultation are presented in thispaper. We obtain angular diameters for 11 sources of which five are thefirst diameter measurements. For these resolved sources we haveestimated the effective temperatures, which are consistent with previouscalibrations. For the other four sources we put the first upper limitson their angular sizes to be 2mas. Two sources, namely IRC+20090 andIRC+20067, yield appreciably low temperatures, which could point totheir possible Mira nature. For sources with Hipparcos parallaxmeasurements, we have calculated the linear radii.
| A homogeneous temperature calibration for K and M giants with an extension to the coolest stars
In this paper we present a new estimate of the effective temperatures of32 giant stars in the spectral range K0 to M10. The sample includes also4 Mira stars. The temperatures are based on a homogeneous set of angulardiameters obtained by our group by the technique of lunar occultations,and using a photometric and spectroscopic coverage with a combination oforiginal measurements and literature data. Most of this basic materialhad been presented in previous papers, but in the present work we deriveimproved effective temperatures by using for the first time a grid ofnumerical center-to-limb darkening models. We use this revision toderive a new calibration of the effective temperature of K and M giantstars, which has the advantage of being based on only one, highlyhomogeneous set of data (while previous calibrations often used mixeddata sets). The resulting calibration is extended to the coolest stars,reaching for the first time M9 for the non-Mira stars, and M10 for theMira stars. In this latter case the calibration does not account forpulsation phase variations and is only tentative. In the region ofoverlap with previously existing calibrations, we find a largelysatisfactory agreement, although some differences exist and arediscussed. In particular, it appears that the calibration of theeffective temperature of cool Mira stars requires additionalobservational as well as theoretical effort. Seven of the stars in oursample appear to exhibit an effective temperature that departssignificantly from the mean relation (~ 900 K cooler between K1 and M8),and no simple explanation in terms of possible bias or experimentalerror could be found. Based on observations collected at TIRGO(Gornergrat, Switzerland), at Calar Alto (Spain) and at the EuropeanSouthern Observatory in La Silla (Chile). TIRGO is operated by CNR --CAISMI Arcetri, Italy. Calar Alto is operated by the German-SpanishAstronomical Center.
| Infrared high angular resolution measurements of stellar sources. IV. Angular diameters and effective temperatures of fifteen late-type stars
We have measured the angular diameter of fifteen late-type stars in thenear-infrared using the technique of lunar occultations. Included areten giant stars in the spectral range K0-M10, three M supergiants andtwo carbon stars. The resulting uniform-disk angular diameters are inthe range 2.5 to 10.0 milliseconds of arc (mas), and the average formalerror is 0.17 mas. In one case where the same occultation has beenobserved from two different locations, the two diameter determinationsagree well within the formal errors. Six of the sources had beenresolved earlier by previous lunar occultation observations, and ourresults are in general agreement and show good reliability. Theremaining nine sources are resolved here for the first time. In the caseof one carbon star, we find a significant departure of the brightnessprofile from a simple uniform disk model. In addition, we have obtainednear-infrared (and partially visual) photometric observations for allthe sources. Complementing this with available literature data at otherwavelengths, we have computed the bolometric fluxes, and used them toderive the effective temperatures. For this purpose, we have applied anominal limb-darkening correction to the angular diameters. The averageaccuracy of our angular diameter determinations is at the level of ~4%,making it possible in principle to achieve uncertainties of 2% or ~50 Kin the effective temperatures, provided that sufficiently accuratebolometric fluxes are available. Due to problems such as scarcity ofphotometric data and variability, bolometric fluxes represent at presentan important limitation in this field. With this work, the set ofangular diameter measurements obtained by our group comprises about 50cool stars. This database will be used in a separate work to derive arefined calibration of the effective temperature of M giant stars. Basedon observations collected at TIRGO (Gornergrat, Switzerland) and atCalar Alto (Spain). TIRGO is operated by CNR -- CAISMI Arcetri, Italy.Calar Alto is operated by the German-Spanish Astronomical Center.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Bika |
| Rektaszcenzió: | 03h53m54.89s |
| Deklináció: | +15°36'41.5" |
| Vizuális fényesség: | 9.153 |
| RA sajátmozgás: | -2 |
| Dec sajátmozgás: | -4.9 |
| B-T magnitude: | 11.408 |
| V-T magnitude: | 9.34 |
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