J/ApJ/753/64 Detailed abundances for 97 metal-poor stars (Ishigaki+, 2012)
Chemical abundances of the Milky Way thick disk and stellar halo.
I. Implications of [α/Fe] for star formation histories in their
progenitors.
Ishigaki M.N., Chiba M., Aoki W.
<Astrophys. J., 753, 64 (2012)>
=2012ApJ...753...64I 2012ApJ...753...64I
ADC_Keywords: Abundances ; Stars, nearby ; Stars, halo ; Milky Way ;
Equivalent widths
Keywords: Galaxy: formation; Galaxy: halo; stars: abundances
Abstract:
we present the abundance analysis of 97 nearby metal-poor
(-3.3<[Fe/H]←0.5) stars having kinematic characteristics of the Milky
Way (MW) thick disk and inner and outer stellar halos. The
high-resolution, high-signal-to-noise optical spectra for the sample
stars have been obtained with the High Dispersion Spectrograph mounted
on the Subaru Telescope. Abundances of Fe, Mg, Si, Ca, and Ti have
been derived using a one-dimensional LTE abundance analysis code with
Kurucz NEWODF model atmospheres. By assigning membership of the sample
stars to the thick disk, inner halo, or outer halo components based on
their orbital parameters, we examine abundance ratios as a function of
[Fe/H] and kinematics for the three subsamples in wide metallicity and
orbital parameter ranges. We show that, in the metallicity range of
-1.5<[Fe/H]≤-0.5, the thick disk stars show constantly high mean
[Mg/Fe] and [Si/Fe] ratios with small scatter. In contrast, the inner
and the outer halo stars show lower mean values of these abundance
ratios with larger scatter. The [Mg/Fe], [Si/Fe], and [Ca/Fe] for the
inner and the outer halo stars also show weak decreasing trends with
[Fe/H] in the range [Fe/H]>-2. These results favor the scenarios that
the MW thick disk formed through rapid chemical enrichment primarily
through Type II supernovae of massive stars, while the stellar halo
has formed at least in part via accretion of progenitor stellar
systems having been chemically enriched with different timescales.
Description:
The high-resolution spectra were obtained in several observing runs
during 2003-2010 with the High Dispersion Spectrograph (HDS) mounted
on the Subaru Telescope. The spectra cover a wavelength range of about
4000-6800Å except for ∼100Å at the gap between the two CCDs at
∼5400Å. For most of the sample stars, a spectral resolution is R
∼50000, while spectra of some sample stars were taken with a higher
resolution (R∼90000).
The data taken before 2010 have already been published (Zhang et al.
2009, Cat. J/ApJ/706/1095; Chiba & Aoki 2010PASJ...62..143I 2010PASJ...62..143I). The new
observations were made in May 26 and June 18.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 79 97 Kinematics of the sample
table4.dat 65 10188 Equivalent widths
table5.dat 102 97 Atmospheric parameters and abundances
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See also:
J/ApJ/749/77 : MW halo. III. Stat. chemical abundances (Schlaufman+, 2012)
J/A+A/530/A15 : Abundances of 94 stars (Nissen+, 2011)
J/ApJ/711/573 : Detailed abundances in a halo stellar stream (Roederer+, 2010)
J/ApJ/706/1095 : Chemical compositions of 26 outer halo stars (Zhang+, 2009)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Object name
12- 16 F5.2 [Sun] [Fe/H] [-3.3/-0.5] Metallicity (1)
18- 23 F6.1 km/s RVel [-372/431] Radial velocity (2)
25- 27 F3.1 km/s e_RVel [0.1/0.8] Uncertainty in RVel
29- 34 F6.1 km/s Vr Velocity of cylindrical radial component
36- 39 F4.1 km/s e_Vr Uncertainty in Vr
41- 46 F6.1 km/s Vphi Velocity of cylindrical azimuthal component
48- 52 F5.1 km/s e_Vphi Uncertainty in Vphi
54- 59 F6.1 km/s Vz Velocity of cylindrical vertical component
61- 64 F4.1 km/s e_Vz Uncertainty in Vz
66- 69 F4.2 --- PTD [0/1] Membership probability for thick disk (3)
71- 74 F4.2 --- PH [0/1] Membership probability for inner halo (3)
76- 79 F4.2 --- POH [0/1] Membership probability for outer halo (3)
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Note (1): Estimated from the high-resolution spectra obtained with Subaru/HDS.
Note (2): Measured from the high-resolution spectra obtained with Subaru/HDS.
Note (3): See Section 2.2.2; equations (1) to (4).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Object name
12- 13 I2 --- Z Atomic number
15 I1 --- Stage [1/2] Ionization stage (1=neutral)
17- 20 A4 --- Ion Element and ionization stage
22- 29 F8.3 0.1nm lambda [4114/6751] Line wavelength λ (in Å)
31- 35 F5.2 [-] log(gf) [-5.7/0.7] log of the oscillator strength
37- 40 F4.2 eV ExPot [0/6] Excitation potential
42- 47 F6.2 0.1nm EW [-1.2/233] Equivalent width of line (in Å)
49 I1 --- Used [0/1]? 1=used in abundance analysis, 0=unused
51- 65 A15 --- r_log(gf) References for log(gf) (1)
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Note (1): Reference as follows:
A07 = Aldenius, M., et al. 2007A&A...461..767A 2007A&A...461..767A
A09 = Aldenius, M., et al. 2009A&A...502..989A 2009A&A...502..989A
BKK91 = Bard, A., Kock, A., and Kock, M., 1991A&A...248..315B 1991A&A...248..315B
BK94 = Bard, A., and Kock, M., 1994A&A...282.1014B 1994A&A...282.1014B
B79a = Blackwell, D. E., et al., 1979MNRAS.186..633B 1979MNRAS.186..633B
B79b = Blackwell, D. E., et al., 1979MNRAS.186..657B 1979MNRAS.186..657B
B80 = Blackwell, D. E., et al., 1980MNRAS.191..445B 1980MNRAS.191..445B
B82a = Blackwell, D. E., et al., 1982MNRAS.199..471F 1982MNRAS.199..471F
B82b = Blackwell, D. E., et al., 1982MNRAS.201..595B 1982MNRAS.201..595B
B86 = Blackwell, D. E., et al., 1986MNRAS.220..549B 1986MNRAS.220..549B
B95 = Blackwell, D. E., et al., 1995A&A...303..575B 1995A&A...303..575B
G73 = Garz, T. 1973A&A....26..471G 1973A&A....26..471G
I06 = Ivans et al. 2006, Cat. J/ApJ/645/613
MB09 = Melendez, J. and Barbuy, B. 2009A&A...497..611M 2009A&A...497..611M
NIST = Ralchenko, Yu., Kramida, A.E., Reader, J., and NIST ASD
Team (2008). NIST Atomic Spectra Database (version 3.1.5),
[Online]. Available: http://physics.nist.gov/asd3 [2010, July 8].
National Institute of Standards and Technology, Gaithersburg, MD
NS10 = Nissen, P. E. & Schuster, W. J. 2010A&A...511A..10C 2010A&A...511A..10C
O91 = O'Brian, T. R., et al. 1991JOSAB...8.1185O 1991JOSAB...8.1185O
P01 = Pickering, J. C., Thorne, A. P., and Perez, R., 2001ApJS..132..403P 2001ApJS..132..403P
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Object name
12- 15 I4 K Teff [4048/6881] Effective temperature
17- 20 F4.2 [cm/s2] log(g) [0.4/5] Log of surface gravity
22- 25 F4.2 km/s Vt [0.04/2.5] Micro-turbulence velocity
27- 31 F5.2 [Sun] [FeI/H] [-3.3/-0.5] Log of Fe I/H abundance
33- 36 F4.2 [Sun] e_[FeI/H] [0.08/0.4] Uncertainty in [FeI/H]
38- 42 F5.2 [Sun] [FeII/H] [-3.3/-0.6] Log of Fe II/H abundance
44- 47 F4.2 [Sun] e_[FeII/H] [0.1/0.8] Uncertainty in [FeII/H]
49- 53 F5.2 [Sun] [Mg/Fe] [-0.1/0.7]?=-9.99 Log of Mg/Fe abundance
55- 58 F4.2 [Sun] e_[Mg/Fe] ?=0 Uncertainty in [Mg/Fe]
60- 64 F5.2 [Sun] [Si/Fe] [-0.2/0.7]?=-9.99 Log of Si/Fe abundance
66- 69 F4.2 [Sun] e_[Si/Fe] ?=0 Uncertainty in [Si/Fe]
71- 75 F5.2 [Sun] [Ca/Fe] [-0.1/0.6]?=-9.99 Log of Ca/Fe abundance
77- 80 F4.2 [Sun] e_[Ca/Fe] ?=0 Uncertainty in [Ca/Fe]
82- 86 F5.2 [Sun] [TiI/Fe] [-0.1/0.9]?=-9.99 Log of Ti I/H abundance
88- 91 F4.2 [Sun] e_[TiI/Fe] ?=0 Uncertainty in [TiI/Fe]
93- 97 F5.2 [Sun] [TiII/Fe] [0.03/0.8]?=-9.99 Log of Ti II/H abundance
99-102 F4.2 [Sun] e_[TiII/Fe] ?=0 Uncertainty in [TiII/Fe]
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History:
From electronic version of the journal
References:
Ishigaki et al. Paper II. 2013ApJ...771...67I 2013ApJ...771...67I Cat. J/ApJ/771/67
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 12-Feb-2014