We performed a detailed study of the ratio of low-α to high-α stars in the Galactic halo as observed by the Gaia-ESO Survey. Using a sample of 381 metal-poor stars from the second internal data release, we found that the value of this ratio did not show evidence of systematic trends as a function of metallicity, surface gravity, Galactic latitude, Galactic longitude, height above the Galactic plane, and Galactocentric radius. We conclude that the αpoor/αrich value of 0.28 ± 0.08 suggests that in the inner halo, the larger portion of stars were formed in a high star formation rate environment, and about 15% of the metal-poor stars originated from much lower star formation rate environments.
Jackson-Jones R., Jofre P., Hawkins K., Hourihane A., Gilmore G., Kordopatis G., et al. (2014). The Gaia-ESO Survey: α-abundances of metal-poor stars. ASTRONOMY & ASTROPHYSICS, 571, L5-L5 [10.1051/0004-6361/201425099].
The Gaia-ESO Survey: α-abundances of metal-poor stars
Lardo C.Membro del Collaboration Group
;
2014
Abstract
We performed a detailed study of the ratio of low-α to high-α stars in the Galactic halo as observed by the Gaia-ESO Survey. Using a sample of 381 metal-poor stars from the second internal data release, we found that the value of this ratio did not show evidence of systematic trends as a function of metallicity, surface gravity, Galactic latitude, Galactic longitude, height above the Galactic plane, and Galactocentric radius. We conclude that the αpoor/αrich value of 0.28 ± 0.08 suggests that in the inner halo, the larger portion of stars were formed in a high star formation rate environment, and about 15% of the metal-poor stars originated from much lower star formation rate environments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
