J/ApJ/732/108 Abundances of 92 giants in Plaut's window (Johnson+, 2011)
Alpha enhancement and the metallicity distribution function of Plaut's window.
Johnson C.I., Rich R.M., Fulbright J.P., Valenti E., McWilliam A.
<Astrophys. J., 732, 108 (2011)>
=2011ApJ...732..108J 2011ApJ...732..108J
ADC_Keywords: Abundances ; Stars, giant ; Milky Way ; Radial velocities
Keywords: Galaxy: abundances - Galaxy: bulge - stars: abundances -
stars: Population II
Abstract:
We present Fe, Si, and Ca abundances for 61 giants in Plaut's window
(l=-1°, b=-8.5°) and Fe abundances for an additional 31 giants
in a second, nearby field (l=0°, b=-8°) derived from
high-resolution (R∼25000) spectra obtained with the Blanco 4m
telescope and Hydra multifiber spectrograph. The median metallicity of
red giant branch (RGB) stars in the Plaut's field is ∼0.4dex lower
than those in Baade's window, and confirms the presence of an iron
abundance gradient along the bulge minor axis. The full metallicity
range of our (biased) RGB sample spans -1.5<[Fe/H]<+0.3, which is
similar to that found in other bulge fields. We also derive a
photometric metallicity distribution function for RGB stars in the
(l=-1°, b=-8.5°) field and find very good agreement with the
spectroscopic metallicity distribution. The radial velocity (RV) and
dispersion data for the bulge RGB stars are in agreement with previous
results of the Bulge Radial Velocity Assay survey, and we find
evidence for a decreasing velocity dispersion with increasing [Fe/H].
The [α/Fe] enhancement in Plaut field stars is nearly identical
to that observed in Baade's window, and suggests that an [α/Fe]
gradient does not exist between b=-4° and -8°. Additionally,
a subset of our sample (23 stars) appears to be foreground red clump
stars that are very metal rich, exhibit small metallicity and RV
dispersions, and are enhanced in α elements. While these stars
likely belong to the Galactic inner disk population, they exhibit
[α/Fe] ratios that are enhanced above the thin and thick disk.
Description:
The spectra for this project were obtained at CTIO using the Blanco 4m
telescope and Hydra multifiber spectrograph. The observations covered
two separate runs spanning 2006 May 27-28 and 2007 May 19-23, and
targeted the approximate spectral regions of 6000-6250, 6150-6400,
6500-6800, and 7650-7950Å.
A set of B, V, and I images for both bulge fields analyzed here
spectroscopically were obtained at the Las Campanas Observatory in
2002 August. We used the optical imager mounted at the Swope 40 inch
telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 92 Program star parameters and results
table2.dat 46 92 Random and systematic uncertainties
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See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/546/A57 : Structure and formation of the Bulge (Uttenthaler+, 2012)
J/A+A/513/A35 : Abundances of Galactic red giants (Alves-Brito+, 2010)
J/A+A/512/A41 : Abundances of microlensed stars in the Bulge (Bensby+, 2010)
J/ApJ/691/1387 : Spectroscopy of the Galactic bar. I. (Rangwala+, 2009)
J/A+A/486/177 : Bulge field stars from FLAMES-GIRAFFE (Zoccali+, 2008)
J/A+A/465/799 : Abundances of Galactic Bulge red giants (Lecureur+, 2007)
J/AJ/134/1432 : Proper motions in Plaut's window (Vieira+, 2007)
J/AJ/131/431 : Abundances of Galactic G dwarfs (Brewer+, 2006)
J/ApJ/636/821 : Abundances of Baade's Window K giants (Fulbright+, 2006)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/433/185 : Abundance analysis of 102 F and G dwarfs (Bensby+, 2005)
J/A+A/410/527 : Abundances in the Galactic disk (Bensby+, 2003)
J/MNRAS/340/304 : [X/Fe] of Galactic disc F and G dwarfs (Reddy+, 2003)
J/AJ/120/1841 : Abundances of Halo and Disk Stars (Fulbright 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS identification (HHMMSSss+DDMMSSs; J2000)
18- 23 F6.3 mag Vmag The V band magnitude (1m Swope Telescope)
25- 30 F6.3 mag Jmag 2MASS J band magnitude
32- 37 F6.3 mag Ksmag 2MASS Ks band magnitude
39- 42 I4 K Teff Effective temperature
44- 47 F4.2 [cm/s2] log(g) Log of the surface gravity
49- 53 F5.2 [Sun] [Fe/H] Metallicity
55- 58 F4.2 km/s Vt Turbulent velocity
60- 64 F5.2 [Sun] [Si/Fe] ? Log of the Si/Fe abundance ratio
66- 70 F5.2 [Sun] [Ca/Fe] ? Log of the Ca/Fe abundance ratio
72- 75 I4 km/s HRV Heliocentric radial velocity
77- 83 A7 --- Note The RGB/Field information (1)
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Note (1): Note as follows:
RGB = probable RGB member;
Clump = probable red clump member;
1 = Field 1 (l=-1 degrees, b=-8.5 degrees);
2 = Field 2 (l=0 degrees, b=-8 degrees)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS identification (HHMMSSss+DDMMSSs; J2000)
18- 21 F4.2 [Sun] re.Fe Random uncertainty in log Fe number abundance
23- 26 F4.2 [Sun] sy.Fe Systematic uncertainty in log Fe number abundance
28- 31 F4.2 [Sun] re.Si ? Random uncertainty in log Si number abundance
33- 36 F4.2 [Sun] sy.Si ? Systematic uncertainty in log Si number abundance
38- 41 F4.2 [Sun] re.Ca ? Random uncertainty in log Ca number abundance
43- 46 F4.2 [Sun] sy.Ca ? Systematic uncertainty in log Ca number abundance
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History:
From electronic version of the journal
Reference:
Johnson et al. Paper II. 2012ApJ...749..175J 2012ApJ...749..175J Cat. J/ApJ/749/175
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Nov-2012