J/AZh/84/997 Abundances of Sr, Y, Zr, Ce and Ba (Mashonkina+, 2007)
Neutron capture elements in halo, thick disk and thin disk stars: strontium,
yttrium, zirconium, cerium.
Mashonkina L.I., Vinogradova A.B., Ptitsyn D.A., Khokhlova V.S.,
Chernetsova T.A.
<Astron. Zh. 84, 997 (2007)>
=2007AZh....84..997M 2007AZh....84..997M
=2007ARep...51..903M 2007ARep...51..903M
ADC_Keywords: Stars, supergiant; Photometry, UBV
Abstract:
Sr, Y, Zr, and Ce abundances are derived for the sample of 74 cool
dwarfs and subgiants with the iron abundance [Fe/H] ranged between
-2.43 and 0.25. The results are based on LTE (Y, Zr and Ce) and
non-LTE (Sr) line formation and line profile analysis of high
resolution (40000 and 60000) spectra that have a typical S/N of
50-200. The Zr/Y, Sr/Y, and Sr/Zr ratios in the halo stars form nearly
a plateau over the wide metallicity range, -2.43≤[Fe/H]≤0.90,
indicating a common origin of Sr, Y, and Zr at the epoch of the halo
formation. We find a steep decline of [Zr/Y] in the thick disk stars
with increasing Ba abundance. This suggests the reduction of the
production rate of Zr compared to that for Y at the active phase of
the thick disk formation. The halo and thick disk stars reveal an
overabundance of Zr relative to barium that grows with decreasing Ba
abundance. There is a clear correlation of the [Zr/Ba] and [Eu/Ba]
abundance ratios. Our observational findings for the halo and thick
disk do not support the Galaxy chemical evolution models available in
the literature and require to improve their predictions. The thin disk
stars reveal, on average, solar abundance ratios for (Y,Zr)/Fe,
(Y,Zr)/Ba, and Zr/Y. We note a slight decline of Zr/Ba and Zr/Y in
these stars with increasing Ba abundance. Our results favour a
dominance of the asymptotic giant branch stars in the heavy element
enrichment of the interstellar gas over the epoch of the thin disk
existence, in agreement with the theory of the main s-process
nucleosynthesis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 53 74 Objects with coordinates
table1.dat 66 15 Atomic data and solar abundances for investigated
lines obtained from solar line profile fitting
table2.dat 70 54 Stellar parameters and element abundance ratios
of the stars with [Fe/H]>-0.9
table3.dat 70 20 Stellar parameters and element abundance ratios
of the stars with [Fe/H]←0.9
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- HD/BD HD/BD number
11- 12 I2 h RAh Right Ascension (2000) (hours)
14- 15 I2 min RAm Right Ascension (2000) (minutes)
17- 23 F7.4 s RAs Right Ascension (2000) (seconds)
25 A1 --- DE- Declination (2000) (sign)
26- 27 I2 deg DEd Declination (2000) (degrees)
29- 30 I2 arcmin DEm Declination (2000) (minutes)
32- 37 F6.3 arcsec DEs Declination (2000) (seconds)
39- 53 A15 --- OName Other name
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Species
8- 14 F7.2 0.1nm lambda Wavelength
17- 21 F5.3 eV Eexc Excitation energy (1)
24- 25 I2 --- Mult Multiplicity number
27- 32 F6.3 [-] loggf log of oscillation strength
35- 36 I2 --- Ref Reference (2)
39- 44 F6.2 --- logC6 C6 abundance
46 A1 --- n_logC6 [1-3] Origin of logC6 (3)
48- 51 F4.2 [-] log(eps) Solar abundance (H=12)
54- 66 A13 --- Rem Remarks
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Note (1): According to Moore, 1972, A multiplet table of astrophysical
interest, NSRD-NBS 40 (Washington, D.C.).
Note (2): References as follows:
13 = Kurucz, 1994, CD-ROM Nos 18, 19
23 = Hannaford et al., 1982ApJ...261..736H 1982ApJ...261..736H
26 = Brage et al., 1998ApJ...496.1051B 1998ApJ...496.1051B
27 = Ljung et al., 2006A&A...456.1181L 2006A&A...456.1181L
28 = Palmeri et al., 2000, Phys. Scr. 61, 323
29 = Reader et al., Wavelengths and Transaction Probabilities for
atoms and atomic ions, PartII, NSRD-NBS 68 (Washington, D.C., 1980)
Note (3): Note as follows:
1 = based on profile analysis for the solar spectrum
2 = data of Kurucz, CD-ROM Nos 18, 19
3 = data of Barklem et O'Mara, 1998MNRAS.300..863B 1998MNRAS.300..863B
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- HD/BD HD number
12- 15 I4 K Teff Effective temperature
18- 21 F4.2 --- logg Surface gravity
24- 28 F5.2 --- [Fe/H] Iron abundance
31- 33 F3.1 km/s VT Microturbulence velocity
36 I1 --- Code [0/3] Stellar population type (1)
39- 43 F5.2 --- [Sr/Fe] ? Strontium to Fe abundance
46- 50 F5.2 --- [Y/Fe] ? Yttrium to Fe abundance
52- 56 F5.2 --- [Zr/Fe] ? Zirconium to Fe abundance
59- 63 F5.2 --- [Ba/Fe] Barium to Fe abundance
66- 70 F5.2 --- [Ce/Fe] ? Cerium to Fe abundance
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Note (1): population is coded as follows:
0 = thin disk
1 = thick disk
2 = halo
3 = transition phase between thin and thick disks
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(End) Veta Avedisova [INASAN] 05-May-2008