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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 =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:
FileName Lrecl Records Explanations
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
Byte-by-byte Description of file: stars.dat
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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
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 26 = Brage et al., 1998ApJ...496.1051B 27 = Ljung et al., 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
Byte-by-byte Description of file: table2.dat table3.dat
Bytes Format Units Label Explanations
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
Note (1): population is coded as follows: 0 = thin disk 1 = thick disk 2 = halo 3 = transition phase between thin and thick disks

(End) Veta Avedisova [INASAN] 05-May-2008
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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