منابع مشابه
Thin and Thick Galactic Disks
Studies of elemental abundances in stars belonging to the thin and the thick disk of our Galaxy are reviewed. Edvardsson et al. (1993) found strong evidence of [α/Fe] variations among F and G main sequence stars with the same [Fe/H] and interpreted these differences as due to radial gradients in the star formation rate in the Galactic disk. Several recent studies suggest, however, that the diff...
متن کاملThe Relative Age of the Thin and Thick Galactic Disks
We determine the relative ages of the open cluster NGC 188 and selected Hipparcos field stars by isochrone fitting, and compare them to the age of the thick disk globular cluster 47 Tuc. The best fit age for NGC 188 was determined to be 6.5 ±1.0 Gyr. The solar metallicity Hipparcos field stars yielded a slightly older thin disk age, 7.5 ±0.7 Gyr. Two slightly metal-poor ([Fe/H] = −0.22) field s...
متن کاملElemental Abundance Survey of The Galactic Thick Disk
We have performed an abundance analysis for Fand Gdwarfs of the Galactic thick disk component. A sample of 176 nearby (d ≤ 150 pc) thick disk candidate stars was chosen from the Hipparcos catalogue and subjected to a high-resolution spectroscopic analysis. Using accurate radial velocities combined with Hipparcos astrometry, kinematics (U, V, and W ) and Galactic orbital parameters were computed...
متن کاملGalactic archaeology: IMF and depletion in the “thin disk”
We determine the initial mass function (IMF) of the “thin disk” by means of a direct comparison between synthetic stellar samples (for different matching choices of IMF, star formation rate SFR and depletion) and a complete (volume-limited) sample of single stars near the galactic plane (|z| < 25pc), selected from the Hipparcos catalogue (d < 100pc, MV < +4.0). Our synthetic samples are compute...
متن کاملBarium even-to-odd isotope abundance ratios in thick disk and thin disk stars
We present the Ba even-to-odd isotope abundance ratios in 25 cool dwarf stars with the metallicity [Fe/H] ranging between 0.25 and –1.35. Our method takes advantage of the hyperfine structure (HFS) affecting the Ba resonance line of the odd isotopes. The fractional abundance of the odd isotopes of Ba is derived from a requirement that Ba abundances from the resonance line λ 4554 and subordin...
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ژورنال
عنوان ژورنال: Astronomische Nachrichten
سال: 2012
ISSN: 0004-6337
DOI: 10.1002/asna.201211698