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VSOP: the variable star one-shot project. I. Project presentation and first data release
Context: About 500 new variable stars enter the General Catalogue ofVariable Stars (GCVS) every year. Most of them however lackspectroscopic observations, which remains critical for a correctassignement of the variability type and for the understanding of theobject. Aims: The Variable Star One-shot Project (VSOP) is aimed at (1)providing the variability type and spectral type of all unstudiedvariable stars, (2) process, publish, and make the data available asautomatically as possible, and (3) generate serendipitous discoveries.This first paper describes the project itself, the acquisition of thedata, the dataflow, the spectroscopic analysis and the on-lineavailability of the fully calibrated and reduced data. We also presentthe results on the 221 stars observed during the first semester of theproject. Methods: We used the high-resolution echelle spectrographsHARPS and FEROS in the ESO La Silla Observatory (Chile) to survey knownvariable stars. Once reduced by the dedicated pipelines, the radialvelocities are determined from cross correlation with synthetic templatespectra, and the spectral types are determined by an automatic minimumdistance matching to synthetic spectra, with traditional manual spectraltyping cross-checks. The variability types are determined by manuallyevaluating the available light curves and the spectroscopy. In thefuture, a new automatic classifier, currently being developed by membersof the VSOP team, based on these spectroscopic data and on thephotometric classifier developed for the COROT and Gaia space missions,will be used. Results: We confirm or revise spectral types of 221variable stars from the GCVS. We identify 26 previously unknown multiplesystems, among them several visual binaries with spectroscopic binaryindividual components. We present new individual results for themultiple systems V349 Vel and BCGru, for the composite spectrum star V4385Sgr, for the T Tauri star V1045 Sco, andfor DM Boo which we re-classify as a BY Draconisvariable. The complete data release can be accessed via the VSOP website.Based on data obtained at the La Silla Observatory, European SouthernObservatory, under program ID 077.D-0085.
| Hidden subluminous stars among the FAUST UV sources towards Ophiuchus
We present results of an analysis of a UV image in the direction ofOphiuchus, obtained with the FAUST instrument. The image contains 228 UVsources. Most of these are identified as normal early-type stars throughcorrelations with catalogued objects. For the first time in this projectwe identify UV sources as such stars by selecting suitable candidates incrowded fields as the bluest objects in colour-colour diagrams usingobservations from the Wise Observatory. These candidates are thenstudied using low-resolution spectroscopy, which allows thedetermination of spectral types to an accuracy of about one-half class,for 60 stars. Synthetic photometry of spectral data is performed inorder to predict the expected UV emission, on the basis of thephotometric information. These results are used along with the Hipparcos/Tycho information, to search for subluminous stars. The comparison ofthe predicted emission with the FAUST measured magnitudes allows us toselect 12 stars as highly probable evolved hot stars. Highsignal-to-noise spectra are obtained for nine of these stars, and Balmerline profiles are compared with the prediction of atmosphere models andwith the spectrum of real stellar atmospheres. Among the ninecandidates, six are classified as previously unrecognized sdB stars, andtwo as white dwarfs. Our result indicates that indeed more brightsubluminous stars are still unrecognized in the existing samples.
| A catalog of far-ultraviolet point sources detected with the fast FAUST Telescope on ATLAS-1
We list the photometric measurements of point sources made by the FarUltraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 spaceshuttle mission. The list contains 4698 Galactic and extragalacticobjects detected in 22 wide-field images of the sky. At the locationssurveyed, this catalog reaches a limiting magnitude approximately afactor of 10 fainter than the previous UV all-sky survey, TDl. Thecatalog limit is approximately 1 x 10-14 ergs A sq cm/s,although it is not complete to this level. We list for each object theposition, FUV flux, the error in flux, and where possible anidentification from catalogs of nearby stars and galaxies. Thesecatalogs include the Michigan HD (MHD) and HD, SAO, the HIPPARCOS InputCatalog, the Position and Proper Motion Catalog, the TD1 Catalog, theMcCook and Sion Catalog of white dwarfs, and the RC3 Catalog ofGalaxies. We identify 2239 FAUST sources with objects in the stellarcatalogs and 172 with galaxies in the RC3 catalog. We estimate thenumber of sources with incorrect identifications to be less than 2%.
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Osservazione e dati astrometrici
| Costellazione: | Ofiuco |
| Ascensione retta: | 17h18m52.38s |
| Declinazione: | -20°29'57.4" |
| Magnitudine apparente: | 8.653 |
| Distanza: | 540.541 parsec |
| Moto proprio RA: | -11.8 |
| Moto proprio Dec: | -6.6 |
| B-T magnitude: | 9.071 |
| V-T magnitude: | 8.688 |
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INHABITED SKY
