A kinematic and abundance survey at the galactic poles

The DDO intermediate band system is used to obtain detailed information about abundance gradients and velocity dispersions in the galaxy, with an emphasis on the properties of halo stars in the range of from 1 to 5 kpc. The DDO abundance index is calibrated agianst (Fe/H) for metal-poor stars, with...

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Veröffentlicht in:The Astronomical journal 1982-12, Vol.87, p.1679-1709
Hauptverfasser: Hartkopf, W. I., Yoss, K. M.
Format: Artikel
Sprache:eng
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Zusammenfassung:The DDO intermediate band system is used to obtain detailed information about abundance gradients and velocity dispersions in the galaxy, with an emphasis on the properties of halo stars in the range of from 1 to 5 kpc. The DDO abundance index is calibrated agianst (Fe/H) for metal-poor stars, with a resulting gradient of about -0.2 per kpc. However, when the sample is divided into two subsamples with (Fe/H) less than -0.5 and equal 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 in metallicity and increase in z distance. The abundances found for high-z stars are similar to the A-star results of Rodgers (1971) in that about half the K giants above 1 kpc appear to have solar abundances.
ISSN:0004-6256
DOI:10.1086/113261