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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
| Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
The availability of the Hipparcos Catalogue has triggered many kinematicand dynamical studies of the solar neighbourhood. Nevertheless, thosestudies generally lacked the third component of the space velocities,i.e., the radial velocities. This work presents the kinematic analysisof 5952 K and 739 M giants in the solar neighbourhood which includes forthe first time radial velocity data from a large survey performed withthe CORAVEL spectrovelocimeter. It also uses proper motions from theTycho-2 catalogue, which are expected to be more accurate than theHipparcos ones. An important by-product of this study is the observedfraction of only 5.7% of spectroscopic binaries among M giants ascompared to 13.7% for K giants. After excluding the binaries for whichno center-of-mass velocity could be estimated, 5311 K and 719 M giantsremain in the final sample. The UV-plane constructed from these datafor the stars with precise parallaxes (σπ/π≤20%) reveals a rich small-scale structure, with several clumpscorresponding to the Hercules stream, the Sirius moving group, and theHyades and Pleiades superclusters. A maximum-likelihood method, based ona Bayesian approach, has been applied to the data, in order to make fulluse of all the available stars (not only those with precise parallaxes)and to derive the kinematic properties of these subgroups. Isochrones inthe Hertzsprung-Russell diagram reveal a very wide range of ages forstars belonging to these groups. These groups are most probably relatedto the dynamical perturbation by transient spiral waves (as recentlymodelled by De Simone et al. \cite{Simone2004}) rather than to clusterremnants. A possible explanation for the presence of younggroup/clusters in the same area of the UV-plane is that they have beenput there by the spiral wave associated with their formation, while thekinematics of the older stars of our sample has also been disturbed bythe same wave. The emerging picture is thus one of dynamical streamspervading the solar neighbourhood and travelling in the Galaxy withsimilar space velocities. The term dynamical stream is more appropriatethan the traditional term supercluster since it involves stars ofdifferent ages, not born at the same place nor at the same time. Theposition of those streams in the UV-plane is responsible for the vertexdeviation of 16.2o ± 5.6o for the wholesample. Our study suggests that the vertex deviation for youngerpopulations could have the same dynamical origin. The underlyingvelocity ellipsoid, extracted by the maximum-likelihood method afterremoval of the streams, is not centered on the value commonly acceptedfor the radial antisolar motion: it is centered on < U > =-2.78±1.07 km s-1. However, the full data set(including the various streams) does yield the usual value for theradial solar motion, when properly accounting for the biases inherent tothis kind of analysis (namely, < U > = -10.25±0.15 kms-1). This discrepancy clearly raises the essential questionof how to derive the solar motion in the presence of dynamicalperturbations altering the kinematics of the solar neighbourhood: doesthere exist in the solar neighbourhood a subset of stars having no netradial motion which can be used as a reference against which to measurethe solar motion?Based on observations performed at the Swiss 1m-telescope at OHP,France, and on data from the ESA Hipparcos astrometry satellite.Full Table \ref{taba1} is only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/165}
| 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).
| 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.
| Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
The Hipparcos satellite made measurements of over 9734 known doublestars, 3406 new double stars, and 11,687 unresolved but possible doublestars. The high angular resolution afforded by speckle interferometrymakes it an efficient means to confirm these systems from the ground,which were first discovered from space. Because of its coverage of adifferent region of angular separation-magnitude difference(ρ-Δm) space, speckle interferometry also holds promise toascertain the duplicity of the unresolved Hipparcos ``problem'' stars.Presented are observations of 116 new Hipparcos double stars and 469Hipparcos ``problem stars,'' as well as 238 measures of other doublestars and 246 other high-quality nondetections. Included in these areobservations of double stars listed in the Tycho-2 Catalogue andpossible grid stars for the Space Interferometry Mission.
| 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
| Classification and Identification of IRAS Sources with Low-Resolution Spectra
IRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed.
| The pulsation, temperatures and metallicities of Mira and semiregular variables in different stellar systems
Data on angular diameters and infrared photometry for late-type starsare assembled. It is shown that a consistent T_eff scale can beestablished, combining results for Mira and non-Mira M-type stars. Thelog T_eff versus (J-K) relation is much steeper than previously adopted,but is consistent with predictions from model stellar atmospheres.Comparison of the linear diameters of Miras measured in the red spectralregion with those measured in the infrared shows that modelssuccessfully predict the extension observed in the red, and the combineddata provide strong evidence that Miras are pulsating in their firstovertone. Data on Miras and semiregular (SR) variables in globularclusters are compared with predictions from stellar evolution andpulsation theory. These data also support a steep log T_eff versus (J-K)relation at low temperatures. The Miras and SR variables in 47 Tucconform to theoretical expectation if they are undergoing an averagemass loss of ~3x10^-7 M_ yr^-1. SR variables in both metal-rich andmetal-poor globular clusters are probably pulsating, like the Miras intheir first overtone. The general agreement between observations andtheory now found suggests that infrared colour-period relations can beused to investigate overall metallicity differences between Miras indifferent stellar systems, at least at the shorter periods wherecircumstellar extinction is probably negligible. A comparison of Mirasin Galactic globular clusters of known metallicity with those in the LMCand in the SgrI window of the Galactic Bulge indicates that Miras ofperiods 100 to 300d in the LMC have a mean metallicity log z~-0.6,whilst those in SgrI have log z~-0.2, close to that of K giants in theNGC 6522 Bulge window. No evidence has yet been found for a dependenceof the Mira period-luminosity relation on metallicity, and it is pointedout that theory does not at present give a definitive prediction of suchan effect. Some stars of special interest are discussed in an appendix.
| A semi-empirical absolute flux calibration in the near infrared: Direct stellar diameters vs. IRFM determinations
A new semi-empirical method to derive the absolute flux calibration inthe near infrared (J,K,L and L' bands) is proposed. The method consistsof the application of the InfraRed Flux Method (IRFM) to a selectedsample of stars with accurate direst measurements of their angulardiameters. The absolute fluxes in each band are obtained minimizing thedifference (theta(IRFM) - theta(direct)). To limit the error in thedetermination of the infrared monochromatic fluxes, required to applythe IRFM, a program of broad band JHKL' photometric observations hasbeen carried out for most of the northern stars in the sample. Whenapplying separately the method to cool and hot stars, the obtainedcalibrations differ by about 8% in all the photometric bands. Thisimplies that the fundamental effective temperatures (derived from directmeasurements of the angular diameters) for cool and hot stars, and thosedetermined from the IRFM are not on the same scale, regardless of theinfrared absolute calibration adopted.
| Chromospheres of metal-deficient field giants
Observations of the 2800-A Mg II line have been obtained with IUE for asample of 10 metal-deficient field giant stars to search forchromospheric emission and signatures of mass loss, as well as toestablish the level of chromospheric radiative energy losses from thesestars. Mg II emission is probably present in all stars. High-resolutionspectra of three of the brightest giants show asymmetric Mg II profileswhich indicate a differentially expanding atmosphere, signaling thepresence of outward mass motions. Surprisingly, the stellar surfacefluxes in the Mg II lines are commensurate with the values found fordisk giant stars (population I) of similar color. In spite ofsubstantially depleted Mg abundances in the target stars (by factors of10-100 relative to the solar abundance), the radiative losses implied bythe Mg II fluxes, and possibly the chromospheric heating mechanism,appear to be reasonably independent of metallicity and age.
| A Catalog of Stellar Angular Diameters Measured by Lunar Occultation
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987AJ.....94..751W&db_key=AST
| The cool components of symbiotic stars. I - Optical spectral types
An analysis of prominent absorption features on red spectra of symbioticstars is presented. The depths of TiO and VO bands appear to becorrelated with the brightness of the system; this behavior is probablythe result of the secondary star heating the outer atmosphere of thecool giant. New spectral types and luminosity classes for the coolcomponents of symbiotics are derived, and these classifications suggesta division into semidetached systems and detached systems. Mass-lossrates for detached symbiotics, which do not contain Mira variables,remain higher than those estimated for single red giants of the samespectral type, suggesting that the presence of a binary companionenhances mass loss in these objects.
| IRAS catalogues and atlases - Atlas of low-resolution spectra
Plots of all 5425 spectra in the IRAS catalogue of low-resolutionspectra are presented. The catalogue contains the average spectra ofmost IRAS poiont sources with 12 micron flux densities above 10 Jy.
| Chromospheric activity and TiO bands in M giants
Low-resolution IUE spectra of 23 cool giant stars ranging from K3through M6 have been used to examine chromospheric activity in late-typegiants. Previous studies have suggested a decrease in the fractionalflux, normalized to bolometric flux, of the Mg II resonance lines (anindicator of chromospheric activity) with effective temperature. Usingmore accurately determined effective temperatures, this decrease isconfirmed and found to be more rapid than previously suggested. A strongcorrelation is found between relative TiO band strengths, as measured bythe Wing TiO index, and the level of chromospheric activity, as measuredby Mg II fluxes. Cool giants which have weak TiO bands relative to themean TiO strengths for stars of similar color also have Mg II lines thatare weaker than the mean. Changes in composition and in chromosphericactivity as a consequence of aging are suggested as a possible origin ofthis interesting relation.
| Chromospheric activity in M giants
Low resolution IUE spectra were obtained for fifteen cool giant starsranging in spectral type from K4.8 thru M5.9. These spectra were used toexamine chromospheric activity and to evaluate the extent to whichnonradiative heating affects the upper levels of cool giantphotospheres. The stars were chosen because of their well determinedwide band colors, TiO band strengths (from wing photometry), angulardiameters (determined from lunar occultations), apparent bolometricfluxes as seen from Earth, and effective preliminary analysis of theseobservations is presented.
| Angular diameters by the lunar occultation technique. V - 26 late-type stars
Near-infrared occultation observations have yielded 37 new angulardiameter measurements for 26 late-type stars. The list includes threecarbon stars and five giants in the range M4-M8. A multichannelphotometer has been tested successfully on five events.
| Spectral energy distribution and effective temperature scale of M-giant stars. II - Application of the infra-red flux method
The stellar effective temperature can be determined on the basis of ananalysis of the shape of the spectral energy distribution curve. Aninvestigation is conducted regarding the possibility of applying theinfrared method for determining stellar effective temperature to K-Mgiant stars. Attention is given to an application of the infrared fluxmethod to cool stars, emergent fluxes and R-values for M-giant stars,effective temperatures of M-giant stars, spectral classification andcolor indices, and the HR diagram of M-giant stars and Mira variables.Several advantages of applying the infrared flux method to K-M giantstars are shown. Difficulties, however, are related to current lists ofspectroscopic data, especially for cool stars. It may, therefore, besafe to confine an application of the infrared flux method at presentonly to the spectral region least disturbed by line absorption.
| Interstellar extinction in the Taurus dark clouds. II
The results of photoelectric photometry of 89 stars in the Vilniusseven-color system in the area of the Taurus dark clouds withcoordinates (1950) 4h16m-4h33m, +16 deg-+20 deg are presented.Photometric spectral types, absolute magnitudes, color excesses,interstellar extinctions and distances of the stars are determined. Thedistance of the dark nebula is found to be 140 pc and is in goodagreement with the distance determined by Straizys and Meistas (1980)for the dark nebula Khavtassi 286, 278. The average extinction in theinvestigated area is of the order of 1.4.
| Effective temperatures of late-type stars - The field giants from K0 to M6
Angular diameters from lunar occultation are combined with infraredphotometry to determine effective temperatures for K0-M6 giants. Therelations between effective temperature and color temperature, MKspectral type, V-K color, and I(104)-L color are derived. The principalresult is a general increase in effective temperature for the coolerspectral types compared to previous calibrations. Throughout thetemperature range studied, excellent agreement is obtained with recentmodel atmosphere computations.
| Twenty-eight angular diameters for late-type stars by the lunar occultation technique
New angular diameter measurements obtained with an infrared photometerare reported. The stars observed include three Mira variables and ninecool IRC objects. Repeat measurements are reported for five stars. Theobservations include numerous daytime and reappearance events. Severalresults obtained with the 4-m telescope verify the value of a largeaperture for the measurement of angular diameters as small as 1.5-2.5milliarcsec.
| Helligkeiten und Eigenbewegungen in den Hyaden. Mit 6 Textabbildungen
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| Positions et Mouvements propres de 357 Etoiles de Repère de la Zone + 16° à + 18° pour l'époque et l'équinoxe 1950,0
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Osservazione e dati astrometrici
| Costellazione: | Toro |
| Ascensione retta: | 04h35m02.37s |
| Declinazione: | +17°12'04.5" |
| Magnitudine apparente: | 6.827 |
| Distanza: | 300.3 parsec |
| Moto proprio RA: | -5.2 |
| Moto proprio Dec: | 0.4 |
| B-T magnitude: | 9.325 |
| V-T magnitude: | 7.034 |
Cataloghi e designazioni:
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