J/ApJ/775/L27 Chemical abundances in a metal-poor RGB star (Johnson+, 2013)
Chemical abundance analysis of a neutron-capture enhanced red giant in the
bulge Plaut field.
Johnson C.I., McWilliam A., Rich R.M.
<Astrophys. J., 775, L27 (2013)>
=2013ApJ...775L..27J 2013ApJ...775L..27J
ADC_Keywords: Abundances ; Stars, giant ; Stars, metal-deficient
Keywords: Galaxy: abundances; stars: abundances; stars: Population II
Abstract:
We present chemical abundances for 27 elements ranging from oxygen to
erbium in the metal-poor ([Fe/H]=-1.67) bulge red giant branch star
2MASS 18174532-3353235. The results are based on equivalent width and
spectrum synthesis analyses of a high-resolution (R∼30000) spectrum
obtained with the Magellan-MIKE spectrograph. While the light (Z≲30)
element abundance patterns match those of similar metallicity bulge
and halo stars, the strongly enhanced heavy element abundances are
more similar to "r-II" halo stars (e.g., CS 22892-052) typically found
at [Fe/H]≲-2.5. We find that the heaviest elements (Z≥56) closely
follow the scaled-solar r-process abundance pattern. We do not find
evidence supporting significant s-process contributions; however, the
intermediate mass elements (e.g., Y and Zr) appear to have been
produced through a different process than the heaviest elements. The
light and heavy element abundance patterns of 2MASS 18174532-3353235
are in good agreement with the more metal-poor r-process enhanced
stars CS 22892-052 and BD +17°3248. 2MASS 18174532-3353235 also
shares many chemical characteristics with the similar metallicity but
comparatively α-poor Ursa Minor dwarf galaxy giant COS 82.
Interestingly, the Mo and Ru abundances of 2MASS 18174532-3353235 are
also strongly enhanced and follow a similar trend recently found to be
common in moderately metal-poor main-sequence turn-off halo stars.
Description:
The spectrum for this project was obtained on 2011 April 3 using the
Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5m
Magellan Clay telescope at Las Campanas Observatory. The instrument
setup provided a resolving power of R∼30000 at 6000Å, with
wavelength coverage spanning approximately 4800-9200Å (red channel
only).
Objects:
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RA (ICRS) DE Designation(s)
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18 17 45.33 -33 53 23.6 2MASS 18174532-3353235 = UCAC2 17581153
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 221 Line list and abundances
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See also:
I/320 : SPM 4.0 Catalog (Girard+, 2011)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/765/157 : Red giants abundances in the Galactic bulge (Johnson+, 2013)
J/ApJ/749/175 : Abundances for stars in Plaut's window (Johnson+, 2012)
J/A+A/530/A54 : Abundances of 650 bulge red giants (Gonzalez+, 2011)
J/ApJ/732/108 : Abundances of 92 giants in Plaut's window (Johnson+, 2011)
J/ApJ/724/975 : Metal-poor stars heavy elements abundances (Roederer+, 2010)
J/ApJ/722/1373 : ω Centauri giants abundances (Johnson+, 2010)
J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)
J/ApJS/182/51 : Transition proba. of rare earth elements (Lawler+, 2009)
J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007)
J/AJ/134/1432 : Proper motions in Plaut's window (Vieira+, 2007)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/A+A/433/185 : Detailed abundance analysis of F & G dwarfs (Bensby+, 2005)
J/ApJ/617/1091 : La and Eu abundances in 85 stars (Simmerer+, 2004)
J/MNRAS/340/304 : [X/Fe] of Galactic disc F and G dwarfs (Reddy+, 2003)
J/AJ/120/1841 : Halo & Disk Stars Abundances & Kinematics (Fulbright 2000)
J/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Sp Species identifier (1)
7- 8 I2 --- Z [8/68] Atomic number
10- 16 F7.2 0.1nm lambda [4966/7836.2] Wavelength (Å)
18- 21 F4.2 eV ExPot [0/5.9] Excitation potential
23- 27 F5.2 [-] log(gf) [-9.8/0.7]? Log of the oscillator strength
29 A1 --- n_Meth [H] Hyperfine structure used (2)
31- 33 A3 --- Meth Method used (3)
35- 57 A23 --- Auth Author's name(s) of the reference
59- 77 A19 --- BibCode Bibcode of the reference
78 A1 --- f_BibCode [c] Flag on the reference (4)
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Note (1): The mean abundance values derived from the lines in this table are
provided in the mini-table below. The columns are the ion identifier,
atomic number, log of solar number abundance, log of the mean number
abundance, the number of lines used to derived the abundance, the
total error on the log of the mean number abundance, and
the abundance relative to Fe.
--------------------------------------
Ion Z logS logA N e_logA A/Fe
--------------------------------------
[O I] 8 8.69 7.73 1 +0.61
Na I 11 6.33 4.55 4 0.05 -0.01
Mg I 12 7.58 6.28 1 +0.47
Al I 13 6.47 4.99 3 0.06 <+0.29
Si I 14 7.55 6.18 8 0.11 +0.40
Ca I 20 6.36 5.01 17 0.12 +0.42
Sc II 21 3.10 1.55 3 0.01 +0.02
Ti I 22 4.99 3.51 20 0.13 +0.29
Ti II 22 4.99 3.67 8 0.10 +0.25
V I 23 4.00 2.34 3 0.09 +0.11
Cr I 24 5.64 4.07 5 0.02 +0.20
Mn I 25 5.39 3.25 6 0.10 -0.37
Fe I 26 7.52 5.75 86 0.12 -1.77
Fe II 26 7.52 5.95 12 0.12 -1.57
Co I 27 4.92 3.32 4 0.12 +0.17
Ni I 28 6.25 4.50 7 0.07 +0.02
Cu I 29 4.21 1.87 2 0.03 -0.57
Rb I 37 2.60 1.21 1 +0.38
Y II 39 2.24 0.81 5 0.08 +0.14
Zr II 40 2.53 1.22 1 +0.26
Mo I 42 1.97 0.92 1 +0.72
Ru I 44 1.84 1.65 2 0.17 <+1.58
Ba II 56 2.13 1.05 3 0.13 +0.49
La II 57 1.13 0.11 4 0.03 +0.55
Ce II 58 1.61 0.41 2 0.05 +0.37
Pr II 59 0.76 -0.41 2 0.06 +0.40
Nd II 60 1.45 0.48 7 0.06 +0.60
Eu II 63 0.52 -0.07 2 0.04 +0.99
Er II 68 0.96 0.55 1 +1.16
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The error includes the measurement error and uncertainty in
Teff±50K, log(g)±0.3(cgs), [M/H]±0.3dex, and
vt±0.3km/s.
Note (2):
H = hyper-fine structure and/or isotopic wavelength shifts were
taken into account.
Note (3): Method used as follows:
Syn = Abundance derived by synthesis measurement.
EW = Abundance derived by equivalent width measurement.
Note (4):
c = 1994, Atomic Data for Opacity Calculations, Kurucz CD-ROM No. 1
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-Mar-2015