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Study of the IR-excess supergiant HD 331319
We report the discovery of brightness variability in the IR-excess earlyF supergiant HD 331319, a candidate post-AGB star. Over three years ofsystematic U BV observations, the star showed low-amplitude (up to in V)quasi-periodic brightness variations on a time scale of 45 days. Apreliminary analysis of our photometry indicates that HD 331319 andother typical post-AGBF supergiants have a similar pattern ofvariability. A study of the extinction toward HD 331319 leads us toconclude that the fraction of the circumstellar extinction is small forthis star. We present low-resolution spectroscopy for HD 331319 anddiscuss the spectral classification of post-AGB F supergiants using HD331319, HD 161796, HD 187885, and HD 56126 as examples.
| Spectral Classification of Stars in A Supplement to the Bright Star Catalogue
MK spectral types are given for about 584 stars in A Supplement to theBright Star Catalogue. These are compared with Hipparcos parallaxes tocheck the reliability of those classifications. The estimated errors are+/-1.2 subtypes, and 10% of the luminosity classes may be wrong.
| UvbyHbeta_ photometry of main sequence A type stars.
We present Stroemgren uvby and Hbeta_ photometry for a set of575 northern main sequence A type stars, most of them belonging to theHipparcos Input Catalogue, with V from 5mag to 10mag and with knownradial velocities. These observations enlarge the catalogue we began tocompile some years ago to more than 1500 stars. Our catalogue includeskinematic and astrophysical data for each star. Our future goal is toperform an accurate analysis of the kinematical behaviour of these starsin the solar neighbourhood.
| Radial velocity measurements. II - Ground-based observations of the program stars for the HIPPARCOS satellite
New radial velocities for 446 stars of magnitude 9.0 or brighter in 1616-sq-deg fields of the Northern Hemisphere are determined by automaticPDS measurement of 80-A/mm-dispersion spectra obtained at theObservatoire de Haute Provence using a 17-cm-diameter objective prism.The fields were selected to provide data for the input catalog of theESA Hipparcos astrometric satellite. The measurement techniques andprecision are discussed, and the results are presented in extensivetables and graphs.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Kugu |
| Sað Açýklýk: | 19h47m59.64s |
| Yükselim: | +31°30'22.6" |
| Görünürdeki Parlaklýk: | 6.798 |
| Uzaklýk: | 91.408 parsek |
| özdevim Sað Açýklýk: | 7 |
| özdevim Yükselim: | 14.1 |
| B-T magnitude: | 6.935 |
| V-T magnitude: | 6.81 |
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