The metal content of bulge field stars from FLAMES-GIRAFFE spectra: I. Stellar parameters and iron abundances

M. Zoccali, V. Hill, A. Lecureur, B. Barbuy, A. Renzini, D. Minniti, A. Gómez, S. Ortolani

Resultado de la investigación: Article

211 Citas (Scopus)

Resumen

Aims. We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes = -4°, = -6°, and = -12°. A fourth field including NGC 6553 is also included in the discussion.Methods. About 800 bulge field K giants were observed with the GIRAFFE spectrograph of FLAMES@VLT at spectral resolution ~ 20000. Several of them were observed again with UVES at ~ 45000 to insure the accuracy of the measurements. The LTE abundance analysis yielded stellar parameters and iron abundances that allowed us to construct an IDF for the bulge that, for the first time, is based on high-resolution spectroscopy for each individual star.Results. The IDF derived here is centered on solar metallicity, and extends from [Fe/H] ~ -1.5 to [Fe/H] ~ +0.5. The distribution is asymmetric, with a sharper cutoff on the high-metallicity side, and it is narrower than previously measured. A variation in the mean metallicity along the bulge minor axis is clearly between = -4° and = -6° ([Fe/H] decreasing ~ by 0.6 dex per kpc). The field at = -12° is consistent with the presence of a gradient, but its quantification is complicated by the higher disk/bulge fraction in this field.Conclusions. Our findings support a scenario in which both infall and outflow were important during the bulge formation, and then suggest the presence of a radial gradient, which poses some challenges to the scenario in which the bulge would result solely from the vertical heating of the bar.

Idioma originalEnglish
Páginas (desde-hasta)177-189
Número de páginas13
PublicaciónAstronomy and Astrophysics
Volumen486
N.º1
DOI
EstadoPublished - jul 2008

Huella dactilar

star distribution
metallicity
iron
metal
distribution functions
metals
gradients
local thermodynamic equilibrium
spectral resolution
spectrographs
outflow
cut-off
spectroscopy
heating
stars
distribution
parameter
high resolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Zoccali, M. ; Hill, V. ; Lecureur, A. ; Barbuy, B. ; Renzini, A. ; Minniti, D. ; Gómez, A. ; Ortolani, S. / The metal content of bulge field stars from FLAMES-GIRAFFE spectra : I. Stellar parameters and iron abundances. En: Astronomy and Astrophysics. 2008 ; Vol. 486, N.º 1. pp. 177-189.
@article{b52485e2ac884d208ef759f7e0498f02,
title = "The metal content of bulge field stars from FLAMES-GIRAFFE spectra: I. Stellar parameters and iron abundances",
abstract = "Aims. We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes = -4°, = -6°, and = -12°. A fourth field including NGC 6553 is also included in the discussion.Methods. About 800 bulge field K giants were observed with the GIRAFFE spectrograph of FLAMES@VLT at spectral resolution ~ 20000. Several of them were observed again with UVES at ~ 45000 to insure the accuracy of the measurements. The LTE abundance analysis yielded stellar parameters and iron abundances that allowed us to construct an IDF for the bulge that, for the first time, is based on high-resolution spectroscopy for each individual star.Results. The IDF derived here is centered on solar metallicity, and extends from [Fe/H] ~ -1.5 to [Fe/H] ~ +0.5. The distribution is asymmetric, with a sharper cutoff on the high-metallicity side, and it is narrower than previously measured. A variation in the mean metallicity along the bulge minor axis is clearly between = -4° and = -6° ([Fe/H] decreasing ~ by 0.6 dex per kpc). The field at = -12° is consistent with the presence of a gradient, but its quantification is complicated by the higher disk/bulge fraction in this field.Conclusions. Our findings support a scenario in which both infall and outflow were important during the bulge formation, and then suggest the presence of a radial gradient, which poses some challenges to the scenario in which the bulge would result solely from the vertical heating of the bar.",
keywords = "Galaxy: bulge, Stars: abundances, Stars: atmospheres",
author = "M. Zoccali and V. Hill and A. Lecureur and B. Barbuy and A. Renzini and D. Minniti and A. G{\'o}mez and S. Ortolani",
year = "2008",
month = "7",
doi = "10.1051/0004-6361:200809394",
language = "English",
volume = "486",
pages = "177--189",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
number = "1",

}

The metal content of bulge field stars from FLAMES-GIRAFFE spectra : I. Stellar parameters and iron abundances. / Zoccali, M.; Hill, V.; Lecureur, A.; Barbuy, B.; Renzini, A.; Minniti, D.; Gómez, A.; Ortolani, S.

En: Astronomy and Astrophysics, Vol. 486, N.º 1, 07.2008, p. 177-189.

Resultado de la investigación: Article

TY - JOUR

T1 - The metal content of bulge field stars from FLAMES-GIRAFFE spectra

T2 - I. Stellar parameters and iron abundances

AU - Zoccali, M.

AU - Hill, V.

AU - Lecureur, A.

AU - Barbuy, B.

AU - Renzini, A.

AU - Minniti, D.

AU - Gómez, A.

AU - Ortolani, S.

PY - 2008/7

Y1 - 2008/7

N2 - Aims. We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes = -4°, = -6°, and = -12°. A fourth field including NGC 6553 is also included in the discussion.Methods. About 800 bulge field K giants were observed with the GIRAFFE spectrograph of FLAMES@VLT at spectral resolution ~ 20000. Several of them were observed again with UVES at ~ 45000 to insure the accuracy of the measurements. The LTE abundance analysis yielded stellar parameters and iron abundances that allowed us to construct an IDF for the bulge that, for the first time, is based on high-resolution spectroscopy for each individual star.Results. The IDF derived here is centered on solar metallicity, and extends from [Fe/H] ~ -1.5 to [Fe/H] ~ +0.5. The distribution is asymmetric, with a sharper cutoff on the high-metallicity side, and it is narrower than previously measured. A variation in the mean metallicity along the bulge minor axis is clearly between = -4° and = -6° ([Fe/H] decreasing ~ by 0.6 dex per kpc). The field at = -12° is consistent with the presence of a gradient, but its quantification is complicated by the higher disk/bulge fraction in this field.Conclusions. Our findings support a scenario in which both infall and outflow were important during the bulge formation, and then suggest the presence of a radial gradient, which poses some challenges to the scenario in which the bulge would result solely from the vertical heating of the bar.

AB - Aims. We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes = -4°, = -6°, and = -12°. A fourth field including NGC 6553 is also included in the discussion.Methods. About 800 bulge field K giants were observed with the GIRAFFE spectrograph of FLAMES@VLT at spectral resolution ~ 20000. Several of them were observed again with UVES at ~ 45000 to insure the accuracy of the measurements. The LTE abundance analysis yielded stellar parameters and iron abundances that allowed us to construct an IDF for the bulge that, for the first time, is based on high-resolution spectroscopy for each individual star.Results. The IDF derived here is centered on solar metallicity, and extends from [Fe/H] ~ -1.5 to [Fe/H] ~ +0.5. The distribution is asymmetric, with a sharper cutoff on the high-metallicity side, and it is narrower than previously measured. A variation in the mean metallicity along the bulge minor axis is clearly between = -4° and = -6° ([Fe/H] decreasing ~ by 0.6 dex per kpc). The field at = -12° is consistent with the presence of a gradient, but its quantification is complicated by the higher disk/bulge fraction in this field.Conclusions. Our findings support a scenario in which both infall and outflow were important during the bulge formation, and then suggest the presence of a radial gradient, which poses some challenges to the scenario in which the bulge would result solely from the vertical heating of the bar.

KW - Galaxy: bulge

KW - Stars: abundances

KW - Stars: atmospheres

UR - http://www.scopus.com/inward/record.url?scp=46649098904&partnerID=8YFLogxK

U2 - 10.1051/0004-6361:200809394

DO - 10.1051/0004-6361:200809394

M3 - Article

AN - SCOPUS:46649098904

VL - 486

SP - 177

EP - 189

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 1

ER -