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HD 91234


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Chemical evolution of the galaxy - A comparison of the abundances of light metals in disk and halo dwarfs
High resolution and high signal-to-noise spectra of 36 field dwarf starshave been obtained in the red and used to calculate Na, Al, Mg, and Siabundances relative to iron, with Fe/H abundance ratios varying between-2.60 and +0.30. The results indicate that the relative abundances oflight metals such as Mg and Si in halo stars are independent of Fe/Hratios, and that the relative abundances of the Al/Mg and Na/Mg ratiosare probably also constant, demonstrating that the odd-even effect isenhanced in the halo. The relative abundances of metals is found tochange progressively form halo-type ratios to disk ratios in the dwarfsof the disk. Interpretations of the observed phenomena include the lightelement abundances being produced in constant ratios in the halo, forexample, by a unique type of supernova; and the disk abundances being amixing of halo and disk abundances leading asymptotically to solarratios.

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Osservazione e dati astrometrici

Costellazione:Sestante
Ascensione retta:10h32m06.39s
Declinazione:+05°14'48.7"
Magnitudine apparente:9.051
Moto proprio RA:-50
Moto proprio Dec:5.9
B-T magnitude:9.622
V-T magnitude:9.099

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 91234
TYCHO-2 2000TYC 259-236-1
USNO-A2.0USNO-A2 0900-06712813

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