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Visible spectroscopy of the new ESO large program on trans-Neptunian objects and Centaurs. Part 1
Aims. A second large observational program was started to improve ourknowledge of the physical properties of Centaurs and trans-Neptunianobjects, TNOs. The program is being executed in the facilities at theCerro Paranal of the European Southern Observatory, ESO, in Chile. Methods: Visible spectroscopy was carried out using FORS1 at the UT2 ofthe VLT telescope. We computed the spectral slope, S, for each object,and we searched for the possible existence of weak absorption features.We compared our data with those from the literature. Results: Wepresent spectra for 21 objects, 7 of them with no previously reportedspectra. Our sample includes 5 Centaurs, 5 resonant objects, 8 classicalTNOs, 2 detached objects, and 1 scattered disk object. There aresignificant differences between the distribution of spectral slopes forCentaurs and classical TNOs. The data presented here generally agreewith previous published data. One exception is 60 558 Echeclus, whosespectral slope is considerably smaller than previous measurements.Another interesting object is 47 932 (2000 GN{171}), which does not showevidence of a proposed feature at 0.7 μm. Most of the spectra arelinear and featureless; however, the well-known bands of solid methaneare detected in 136 199 Eris spectra and some weak features are detectedfor a few other objects. The most interesting case is that of 2003AZ{84}, which has a feature at about 0.65 μm, maybe due to aqueousalteration.Based on observations at the VLT Observatory Cerro Paranal of EuropeanSouthern Observatory, ESO, Chile, in the framework of program178.C-0036.
| CCD astrometry and components instrumental magnitude difference of 432 Hipparcos wide visual double stars
Context: We measured the angular separations, position angles, ΔV, Δ y and Δ I of wide visual double stars during the period2003-2005. At least one component of the double stars in our sample hasan entry in the Hipparcos catalogue. Aims: Our measurements are acontribution to the study of the nature of these double stars. Methods: The northern double stars of the project were observed with the1.2 m telescope of the Kryonerion observatory and the southern with the1.0 m SAAO. We performed multiple-exposure CCD imaging of our targetsand used the standard procedure of data reduction and astrometric CCDcalibrations. Results: We present measurements of 213 northern and 219southern wide binaries.Based on observations made at Kryonerion Observatory of the NationalObservatory of Athens, Greece, and the South African AstronomicalObservatory. Full Table 1 and Tables 2, 3 are only available inelectronic form at the 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/472/1055
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| 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.
| Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
| Close visual binaries. III - Parameters and evolutionary status
New Yale isochrones, which have been tested for accuracy by Corbally(1984), provide the means to investigate interesting visual binaries,especially those whose classifications and photometry do not match well.Various parameters are deduced for those binaries which fitted theisochrones (e.g. ages, metal abundances, luminosities of peculiarstars); various solutions are systematically developed for those whichdid not fit; and a likely status of evolution is proposed (e.g.,duplicity of the components, premain-sequence, blue straggler,horizontal branch, optical pair, data inaccuracies). Evolution aroundthe helium flash and diffusion theory are briefly considered. Theseparameters and statuses provide a wealth of new stellar data andsuggestions for further investigation.
| Close visual binaries. II - Quantitative test of isochrones
Homogeneous and accurate color-magnitude data are available from Paper Ifor each component of 56 close visual binaries, 30 with evolvedcomponents. The 21 binaries with main-sequence primaries are comparedwith new Yale isochrones to determine the appropriate isochronecomposition: Y = 0.25, Z = 0.04. Explanations are given for eightbinaries found to be inconsistent with this isochrone. Some of theremaining binaries suggest a decrease by 0.5 in the mixing lengthparameter for the reddest main-sequence stars, and either a smallerdecrease or mass loss in the subgiant and giant phase of evolution. Ingeneral, the mean apparent age difference between binary components (0.0+ or - 0.1 Gyr) shows stellar evolution to be well modeled by the newYale isochrones.
| Close visual binaries. I - MK classifications
Each component of 170 close visual binaries has been classified with newprocedures for controlling contamination problems. These classificationsare presented and are shown to be on the MK system. Two sources of areascanner UBV photometry were compared in order to establish homogeneousphotometric as well as spectroscopic data. From a consideration ofsystematic errors in the V magnitude difference (Delta V) betweencomponents the photometry of Hurly and Warner (1983) is to be preferred.Absolute magnitudes for each binary are derived from Delta V via atested MK - M(v) map.
| Area Scanner Observations of Close Visual Double Stars - Part Two - Results for 153 Southern Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983MNRAS.202..761H&db_key=AST
| Erratum - Discordances Between SAO and HD Numbers for Bright Stars
Not Available
| Combined-light UBV Photometry of 103 Bright Southern Visual Doubles
Not Available
| 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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Osservazione e dati astrometrici
| Costellazione: | Centauro |
| Ascensione retta: | 12h24m44.72s |
| Declinazione: | -41°23'03.4" |
| Magnitudine apparente: | 6.334 |
| Moto proprio RA: | -65.4 |
| Moto proprio Dec: | -66.9 |
| B-T magnitude: | 7.949 |
| V-T magnitude: | 6.468 |
Cataloghi e designazioni:
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