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Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| Southern subdwarf photometry
UBV photometry and normalized UV excesses are reported for 176 southernmetal-poor stars selected from the objective-prism survey of Bidelmanand MacConnell (1973) as well as 49 other metal-deficient starsidentified in other surveys. Photometry is also presented for 32 otherstars lying near the 225 program stars (although not explicitlyidentified as such in the text, the program stars are apparentlysubdwarfs and subdwarf candidates). Previously determined spectral typesand degrees of line weakening are given for the 225 stars, andmetallicities are estimated on the basis of the degrees of lineweakening. It is noted that 33 F and G stars with extreme meannormalized UV excesses of approximately 0.22 mag have a mean Fe/H valueof -1.4 and probably represent halo subdwarfs, while 82 F and G starswith moderate UV excesses are mostly old disk stars.
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Observation and Astrometry data
| Constellation: | Grus |
| Right ascension: | 21h36m24.10s |
| Declination: | -40°40'46.7" |
| Apparent magnitude: | 8.562 |
| Distance: | 123.609 parsecs |
| Proper motion RA: | -8.4 |
| Proper motion Dec: | 4.8 |
| B-T magnitude: | 9.191 |
| V-T magnitude: | 8.614 |
Catalogs and designations:
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