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Extremely metal-deficient red giants. I - A new objective-prism, photometric, and radial-velocity survey
Results of an extensive objective-prism survey to detect extremelymetal-deficient red giants and a subsequent investigation of thephotometric and radial velocity properties of the newly discovered starsare presented. The 132 red giants with Fe/H abundance ratios less thanor equal to -1.5 discovered in the present objective-prism survey on a10-deg prism down to B magnitudes of 11.5, and by previousobjective-prism and other surveys, are listed, together with results ofradial velocity and photometric measurements. Examination of theStromgren m1 index calibrated against high-resolution spectroscopicdeterminations of the Fe-H abundance ratio indicates that population IIIfield giants with abundance ratios less than -3 are extremely rare. TheStromgren c1 index is used as an indicator of surface gravity andanomalous CH strengths, resulting in the identification of field redhorizontal-branch stars, field asymptotic-branch giants and subgiants.Radial velocities obtained for about half the stars reveal thatessentially all of them have halo motions, and that the incidence ofspectroscopic binaries is very low.
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Osservazione e dati astrometrici
| Costellazione: | Triangolo Australe |
| Ascensione retta: | 15h38m44.23s |
| Declinazione: | -61°49'38.8" |
| Magnitudine apparente: | 8.562 |
| Distanza: | 10000000 parsec |
| Moto proprio RA: | -13.5 |
| Moto proprio Dec: | -16.6 |
| B-T magnitude: | 10.447 |
| V-T magnitude: | 8.718 |
Cataloghi e designazioni:
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