TY - JOUR
T1 - Zinc abundances in Galactic bulge field red giants
T2 - Implications for damped Lyman- α systems ∗ ∗ ∗
AU - Barbuy, B.
AU - Friaça, A. C.S.
AU - Da Silveira, C. R.
AU - Hill, V.
AU - Zoccali, M.
AU - Minniti, D.
AU - Renzini, A.
AU - Ortolani, S.
AU - Gómez, A.
N1 - Funding Information:
B.B. acknowledges partial financial support by CNPq, CAPES, and FAPESP. C.R.S. acknowledges a CAPES/PROEX Ph.D. fellowship. M.Z. and D.M. acknowledge support by the Ministry of Economy, Development, and Tourism’s Millenium Science Initiative through grant IC120009, awarded to The Millenium Institute of Astrophysics, MAS, and from the BASAL Center for Astrophysics and Associated Technologies PFB-06 and FONDECYT Projects 1130196 and 1150345. S.O. acknowledges the Italian Ministero dell’Università e della Ricerca Scientifica e Tecnologica (MURST), Italy.
Publisher Copyright:
© 2015 ESO.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - Context. Zinc in stars is an important reference element because it is a proxy to Fe in studies of damped Lyman- systems (DLAs), permitting a comparison of chemical evolution histories of bulge stellar populations and DLAs. In terms of nucleosynthesis, it behaves as an alpha element because it is enhanced in metal-poor stars. Abundance studies in different stellar populations can give hints to the Zn production in different sites. Aims. The aim of this work is to derive the iron-peak element Zn abundances in 56 bulge giants from high resolution spectra. These results are compared with data from other bulge samples, as well as from disk and halo stars, and damped Lyman- systems, in order to better understand the chemical evolution in these environments. Methods. High-resolution spectra were obtained using FLAMES+UVES on the Very Large Telescope. We computed the Zn abundances using the Zn i lines at 4810.53 and 6362.34 We considered the strong depression in the continuum of the Zn i 6362.34 line, which is caused by the wings of the Ca i 6361.79 line suffering from autoionization. CN lines blending the Zn i 6362.34 A line are also included in the calculations. Results. We find [Zn/Fe] = +0.24 ?0.02 in the range a'1.3 < [Fe/H] < a'0.5 and [Zn/Fe] = +0.06 ?0.02 in the range a'0.5 < [Fe/H] < a'0.1, whereas for [Fe/H] ≥ a'0.1, it shows a spread of a'0.60 < [Zn/Fe] < +0.15, with most of these stars having low [Zn/Fe] < 0.0. These low zinc abundances at the high metallicity end of the bulge define a decreasing trend in [Zn/Fe] with increasing metallicities. A comparison with Zn abundances in DLA systems is presented, where a dust-depletion correction was applied for both Zn and Fe. When we take these corrections into account, the [Zn/Fe] vs. [Fe/H] of the DLAs fall in the same region as the thick disk and bulge stars. Finally, we present a chemical evolution model of Zn enrichment in massive spheroids, representing a typical classical bulge evolution.
AB - Context. Zinc in stars is an important reference element because it is a proxy to Fe in studies of damped Lyman- systems (DLAs), permitting a comparison of chemical evolution histories of bulge stellar populations and DLAs. In terms of nucleosynthesis, it behaves as an alpha element because it is enhanced in metal-poor stars. Abundance studies in different stellar populations can give hints to the Zn production in different sites. Aims. The aim of this work is to derive the iron-peak element Zn abundances in 56 bulge giants from high resolution spectra. These results are compared with data from other bulge samples, as well as from disk and halo stars, and damped Lyman- systems, in order to better understand the chemical evolution in these environments. Methods. High-resolution spectra were obtained using FLAMES+UVES on the Very Large Telescope. We computed the Zn abundances using the Zn i lines at 4810.53 and 6362.34 We considered the strong depression in the continuum of the Zn i 6362.34 line, which is caused by the wings of the Ca i 6361.79 line suffering from autoionization. CN lines blending the Zn i 6362.34 A line are also included in the calculations. Results. We find [Zn/Fe] = +0.24 ?0.02 in the range a'1.3 < [Fe/H] < a'0.5 and [Zn/Fe] = +0.06 ?0.02 in the range a'0.5 < [Fe/H] < a'0.1, whereas for [Fe/H] ≥ a'0.1, it shows a spread of a'0.60 < [Zn/Fe] < +0.15, with most of these stars having low [Zn/Fe] < 0.0. These low zinc abundances at the high metallicity end of the bulge define a decreasing trend in [Zn/Fe] with increasing metallicities. A comparison with Zn abundances in DLA systems is presented, where a dust-depletion correction was applied for both Zn and Fe. When we take these corrections into account, the [Zn/Fe] vs. [Fe/H] of the DLAs fall in the same region as the thick disk and bulge stars. Finally, we present a chemical evolution model of Zn enrichment in massive spheroids, representing a typical classical bulge evolution.
KW - Galaxies: evolution
KW - Galaxy: bulge
KW - Stars: abundances
UR - http://www.scopus.com/inward/record.url?scp=84938083534&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201525694
DO - 10.1051/0004-6361/201525694
M3 - Article
AN - SCOPUS:84938083534
SN - 0004-6361
VL - 580
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A40
ER -