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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.
| Synthetic light-curve method applied to the W UMa systems SY Horologii and VY Ceti
Photoelectric observations of SY Hor and VY Cet have yielded completelight curves in the UBV system. These new observations are used toderive up-dated ephemeris and to provide photometric solutions by theWilson and Devinney's technique. Both systems are found to be W-typecontact binaries with a shallow percentage of overcontact. Concerningthe A and W classification for W UMa stars, a new photometric criterion- based on the asymmetry in the light curves at maximum light - ispresented and applied to both binaries. This asymmetry is explained asbeing due to the limb darkening effect when applied to the Roche modelconfiguration.
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Osservazione e dati astrometrici
| Costellazione: | Orologio |
| Ascensione retta: | 04h13m46.74s |
| Declinazione: | -46°11'10.5" |
| Magnitudine apparente: | 9.028 |
| Moto proprio RA: | 21.4 |
| Moto proprio Dec: | 3 |
| B-T magnitude: | 10.801 |
| V-T magnitude: | 9.175 |
Cataloghi e designazioni:
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