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A kinematic and abundance survey at the galactic poles
The DDO intermediate band system is used to obtain detailed informationabout abundance gradients and velocity dispersions in the galaxy, withan emphasis on the properties of halo stars in the range of from 1 to 5kpc. The DDO abundance index is calibrated agianst (Fe/H) for metal-poorstars, with a resulting gradient of about -0.2 per kpc. However, whenthe sample is divided into two subsamples with (Fe/H) less than -0.5 andequal to or greater than -0.5, the gradients are -0.14 and 0.00,respectively. DDO observations of about 1000 stars, mostly G5-K5 giants,show that the velocity dispersion increases both with decrease inmetallicity and increase in z distance. The abundances found for high-zstars are similar to the A-star results of Rodgers (1971) in that abouthalf the K giants above 1 kpc appear to have solar abundances.
| The K-giant population at the South Galactic Pole
CN anomalies and distances from the galactic plane have been derivedthrough DDO photometry for 171 late-type giant and subgiant stars nearthe South Galactic Pole. The previously found trend of the difference inCN concentration with distance (approximately equal to 0.09/kpc) holdsto approximately 2 kpc, but at greater distances from the plane theslope becomes approximately zero. The giants beyond 2 kpc are ofessentially normal composition or only slightly underabundant in heavierelements.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yontar |
| Sað Açýklýk: | 00h40m47.05s |
| Yükselim: | -30°51'33.8" |
| Görünürdeki Parlaklýk: | 8.468 |
| Uzaklýk: | 198.02 parsek |
| özdevim Sað Açýklýk: | 7.7 |
| özdevim Yükselim: | -2.7 |
| B-T magnitude: | 9.618 |
| V-T magnitude: | 8.563 |
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