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SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
| A large, complete, volume-limited sample of G-type dwarfs. I. Completion of Stroemgren UVBY photometry
Four-colour photometry of potential dwarf stars of types G0 to K2,selected from the Michigan Spectral Catalogues (Vol. 1-3), has beencarried out. The results are presented in a catalogue containing 4247uvby observations of 3900 stars, all south of δ = -26deg. Theoverall internal rms errors of one observation (transformed to thestandard system) of a program star in the interval 8.5 < V < 10.5are 0.0044, 0.0021, 0.0039, and 0.0059, respectively, in V, b-y, m_1_ ,and c_1_. The purpose of the catalogue, combined with earliercatalogues, is to allow selection of a large, complete, volume-limitedsample of G- and K-type dwarfs, investigate their metallicitydistribution, and compare it to predictions of various models ofgalactic chemical evolution. Future papers in this series will discussthese subjects.
| Rapid oscillations of five stars in the spectral range G and K. II
The five stars HD 11112, HD 170747, HD 186651, HD 205390 and HD 224834are a second group of objects enclosed in a larger observational programfor the search of rapid oscillations. They have been observed with the50 cm photoelectrical ESO telescope at La Silla (Chile). For the star HD205390 a variation of 163.8 min was found. The two objects HD 11112 andHD 186651 are suspected to be variable with periods of 139 min and 142.2min and its overtones, respectively. But a verification of these resultsis necessary. For the last two objects HD 170747 and HD 224834 novariations were detected.
| UvbyH-beta photoelectric and CCD photometry of IC 4651
An analysis of uvbyH-beta photoelectric and CCD photometry of IC4651shows a Fe/H abundance ratio of 0.23 + or - 0.02, an E(b-y) value of0.064 + or - 0.006, and an age on the system of VandenBerg (1985) of 2.4+ or - 0.2 x 10 to the 9th yr. Scatter noted in the clustercolor-magnitude diagram can be explained by binaries, nonmembers, and ablueward hook due to the hydrogen-exhaustion phase. The cluster turnoffindicates some evidence for the presence of bimodality which issuggested to be the result of nonstandard evolution near theBohm-Vitense gap.
| Radial velocities of bright southern stars. V - 146 Population II F stars and related stars
This paper presents new radial velocity determinations, based on 20 A/mmcoude plates, for 146 southern stars brighter than m(v) = 8.3. Drawnfrom the catalog of uvby-beta photometry of southern A5-G0 stars byOlsen (1983), the program stars are certain or suspected Population IIstars. One triple-lined and 10 double-lined binaries have been detected,including HD 210737, for which a preliminary orbit has been derived.Notes on spectral peculiarities are given.
| Preliminary UVBY calibrations for G and K type dwarf stars
Four-color uvby photometry for several hundred late-type dwarf stars oftypes G, K and M is discussed. Mean values of photometric indices aregiven for MK spectral types between F8/G0V and M2V. Preliminary standardrelations between the four-color indices are derived. Based onparallaxes and results from high-dispersion spectroscopic analyses,calibrations of the observed indices in terms of Mv, log Te and Fe/Hhave been derived. The means errors are 0.29 mag, 0.009 dex, and 0.17dex, respectively. The calibrations are valid for class-V stars of allpopulations between G0 and M2. If extreme population-II dwarfs areexcluded, the mean error of the abundance calibration decreases to 0.13dex. Calibrations in terms of log g have been attempted,, but the lowaccuracy of the spectroscopic g determinations does not inspireconfidence in the results. The possible contribution of a'fourth-parameter' variation to the mean errors of the calibrations isbriefly discussed. This fourth parameter could be the intrinsic heliumabundance of the stars.
| Estimation of spectral classifications for bright southern stars with interesting Stromgren indices
This paper investigates the degree of success with which uvby photometrycan be applied to predict spectral classifications for 947 A, F, and Gstars brighter than an apparent magnitude of 8.3 and with four-colorindices indicating some kind of interesting, unusual, or peculiarspectrum. One or several possible spectral classifications are estimatedfor each star from photometry alone, double stars are distinguished, andthe estimates are compared with published classifications. The resultsshow that the framework provided by uvby photometry can be extended toinclude most G and K stars, reddened stars, peculiar stars, and certaintypes of double star.
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Osservazione e dati astrometrici
| Costellazione: | Sagittario |
| Ascensione retta: | 18h32m14.01s |
| Declinazione: | -29°11'24.7" |
| Magnitudine apparente: | 7.043 |
| Distanza: | 123.457 parsec |
| Moto proprio RA: | 5.9 |
| Moto proprio Dec: | 4.1 |
| B-T magnitude: | 8.059 |
| V-T magnitude: | 7.127 |
Cataloghi e designazioni:
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