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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.
| The nature of the F STR 4077-A stars. II - Frequency, kinematics, metallicity, binarity and rotational velocities
Fundamental characteristics of the F str 4077-A stars are investigated.Their frequency in the solar neighborhood is estimated at about 1.4percent of all main-sequence F stars. The space velocities areconsistent with Population I membership, with the exception of oneobject (in a sample of 17) whose velocity is above 100 km/s. The binaryfrequency is higher than normal, and the rotational velocities arenormal for the cooler stars but rather low for the hotter ones. Overallmetallicity, deduced from photometric and CORAVEL data, suggests adivision of these stars into two groups: metal-rich objects (generallythe hotter ones), which may resemble the Am or Ap stars, and slightlymetal-weak objects (generally the cooler ones), which may be linked withthe Ba II giants or the CH subgiants.
| The nature of the F STR lambda 4077 stars
Geneva photometry of seven stars classified F str 4077-A stars byBidelman (1981) is presented. Published uvby-beta measurements of fiveadditional stars of this type are used, as well to look for a possiblelink with the classical Am or Ap stars. It is shown that these starsexhibit a whole range of metallicities, the latter being correlated witheffective temperature. The existing proper motions point to a PopulationI membership, although one star seems to have a rather high velocity. Itis suggested that this new type of peculiarity may be interpreted in theframework of the diffusion theory and that at least some F str 4077-Astars may represent an intermediate stage between Am and Lambda Bootisstars, although they are generally cooler.
| Objective-prism discoveries in the declination zone 0 deg to -20 deg
An inspection of 130 10-deg-prism plates taken for the University ofMichigan Southern Spectral Survey has yielded 154 new peculiar orotherwise interesting stars. The regions surveyed are mainly at fairlyhigh galactic latitudes; this fills a gap in previous work of this type.About three-quarters of the objects will eventually be reclassified byHouk in a systematic work on all of the Henry Draper Catalogue stars,but many of these are of sufficient interest to justify earlypublication.
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Osservazione e dati astrometrici
| Costellazione: | Idra |
| Ascensione retta: | 09h50m00.46s |
| Declinazione: | -21°07'46.0" |
| Magnitudine apparente: | 8.693 |
| Distanza: | 393.701 parsec |
| Moto proprio RA: | 4.3 |
| Moto proprio Dec: | 0.5 |
| B-T magnitude: | 8.982 |
| V-T magnitude: | 8.717 |
Cataloghi e designazioni:
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