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J/A+A/534/A80  Metallicity of bulge clump giants in Baade's window (Hill+, 2011)

The metallicity distribution of bulge clump giants in Baade's window. Hill V., Lecureur A., Gomez A., Zoccali M., Schultheis M., Babusiaux C., Royer F., Barbuy B., Arenou F., Minniti D., Ortolani S. <Astron. Astrophys. 534, A80 (2011)> =2011A&A...534A..80H
ADC_Keywords: Stars, giant ; Abundances, [Fe/H] ; Photometry, UBVRI ; Photometry, infrared Keywords: Galaxy: bulge - Galaxy: formation - Galaxy: abundances - stars: abundances - stars: atmosphere Abstract: We seek to constrain the formation of the Galactic bulge by means of analysing the detailed chemical composition of a large sample of red clump stars in Baade's window. These stars were selected to minimise the contamination by other Galactic components, so they are good tracers of the bulge metallicity distribution in Baade's window, at least for stars more metal-rich than ~-1.5. We used an automatic procedure to measure [Fe/H] in a sample of 219 bulge red clump stars from R=20000 resolution spectra obtained with FLAMES/GIRAFFE at the VLT. The analysis was performed differentially with respect to the metal-rich local reference star MuLeo. For a subsample of 162 stars, we also derived [Mg/H] from spectral synthesis around the MgI triplet at 6319Å. The Fe and Mg metallicity distributions are both asymmetric with median values of +0.16 and +0.21, respectively. They show only a small proportion of stars at low metallicities, extending down to [Fe/H]=-1.1 or [Mg/H]=-0.7 The iron distribution is clearly bimodal, as revealed both by a deconvolution (from observational errors) and a Gaussian decomposition. The decomposition of the observed Fe and Mg metallicity distributions into Gaussian components yields two populations of equal sizes (50% each): a metal-poor component centred on [Fe/H]=-0.30 and [Mg/H]=-0.06 with a large dispersion and a narrow metal-rich component centred on [Fe/H]=+0.32 and [Mg/H]=+0.35. The metal-poor component shows high [Mg/Fe] ratios (around 0.3), while stars in the metal-rich component are found to have near solar ratios. Kinematical differences between the two components have also been found: the metal-poor component shows kinematics compatible with an old spheroid, while the metal-rich component is consistent with a population supporting a bar. In view of their chemical and kinematical properties, we suggest different formation scenarii for the two populations: a rapid formation time scale as an old spheroid for the metal-poor component (old bulge) and for the metal-rich component, a formation on a longer time scale driven by the evolution of the bar (pseudo-bulge). Description: Stellar parameters and [Fe/H] and [Mg/H] abundances (and associated uncertainties) are given for a sample of 220 red clump stars selected in Baade's Window towards the Galactic Bulge and observed at a resolution of R=20,000 with the FLAMES/VLT multi-object spectrograph. The cross-identified UBVI (OGLE) and JHK (2MASS) photometry used for initial stellar parameter determination are also given. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 132 220 UBVI and JHK photometry for the selected 220 red clump stars in Baade's Window table2.dat 54 220 Stellar parameters, [Fe/H] and [Mg/H] of the 220 red clump stars in Baade's Window table3.dat 73 220 Uncertainties on the stellar parameters and associated uncertainties on [Fe/H] abundances of the 220 red clump stars in Baade's Window
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/AcA/49/319 : OGLE UBVI phot. in Baade's Window (Paczynski+, 1999) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Star Star name (BWc-NNN) 9- 16 A8 --- --- (BUL-SC45) 18- 23 I6 --- OGLE OGLE identifier, BUL-SC45 NNNNNN, from Paczynski et al., 1999, Cat. J/AcA/49/319 25- 30 F6.3 mag Umag Johnson U magnitude 32- 36 F5.3 mag e_Umag rms uncertainty on Umag 38- 43 F6.3 mag Bmag Johnson B magnitude 45- 49 F5.3 mag e_Bmag rms uncertainty on Bmag 51- 56 F6.3 mag Vmag Johnson V magnitude 58- 62 F5.3 mag e_Vmag rms uncertainty on Vmag 64- 69 F6.3 mag Imag Johnson I magnitude 71- 75 F5.3 mag e_Imag rms uncertainty on Imag 77- 93 A17 --- 2MASS 2MASS identifier 95-100 F6.3 mag Jmag 2MASS J magnitude 102-106 F5.3 mag e_Jmag rms uncertainty on Jmag 108-113 F6.3 mag Hmag 2MASS H magnitude 115-119 F5.3 mag e_Hmag rms uncertainty on Hmag 121-126 F6.3 mag Kmag 2MASS K magnitude 128-132 F5.3 mag e_Kmag rms uncertainty on Kmag
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Star Star name 9- 12 I4 K Teff Effective Temperature 14- 17 F4.2 [cm/s2] logg Surface gravity 19- 21 F3.1 km/s vt Microturbulence velocity 23- 27 F5.2 [Sun] [Fe/H] Fe/H abundance 29- 32 F4.2 [Sun] e_[Fe/H] Uncertainty on [Fe/H] (lower value) 34- 37 F4.2 [Sun] E_[Fe/H] Uncertainty on [Fe/H] (upper value) 40- 44 F5.2 [Sun] [Mg/H] ?=99.99 Mg/H abundance 46- 49 F4.2 [Sun] e_[Mg/H] ?=9.99 Uncertainty on [Mg/H] (lower value) 51- 54 F4.2 [Sun] E_[Mg/H] ?=9.99 Uncertainty on [Mg/H] (upper value)
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Star Star name 9- 12 I4 K Teff Effective Temperature 14- 17 F4.2 [cm/s2] logg Surface gravity 19- 21 F3.1 km/s vt Microturbulence velocity 23- 27 F5.2 [Sun] [Fe/H] Metallicity ([Fe/H] abundance) 31- 34 F4.2 km/s e_vt Uncertainty on the microturbulence velocity (lower value) 36- 39 F4.2 [Sun] E_[Fe/H]vt Uncertainty on Fe (upper value) arising from the uncertainty on the microturbulence velocity (lower value) 41- 43 I3 K E_Teff Uncertainty on the effective temperature (upper value) 45- 48 F4.2 [Sun] E_[Fe/H]T Uncertainty on Fe (upper value) arising from the uncertainty on the effective temperature (upper value) 53- 56 F4.2 km/s E_vt Uncertainty on the microturbulence velocity (upper value) 59- 62 F4.2 [Sun] e_[Fe/H]vt Uncertainty on Fe (lower value) arising from the uncertainty on the microturbulence velocity (upper value) 65- 67 I3 K e_Teff Uncertainty on the effective temperature (lower value)(T) 70- 73 F4.2 [Sun] e_[Fe/H]T Uncertainty on Fe (lower value) arising from the uncertainty on the effective temperature (lower value)
Acknowledgements: Vanessa Hill, Vanessa.Hill(at)oca.eu History: * 05-Oct-2011: on-line version * 28-Jan-2013: Signs of 2MASS name corrected
(End) Patricia Vannier [CDS] 26-Aug-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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