Access to Astronomical Catalogues

← Click to display the menu
J/A+A/608/A89     Very metal poor stars in MW halo           (Mashonkina+, 2017)

The formation of the Milky Way halo and its dwarf satellites, a NLTE-1D abundance analysis. II. Early chemical enrichment. Mashonkina L., Jablonka P., Sitnova T, Pakhomov Yu, North P. <Astron. Astrophys. 608, A89 (2017)> =2017A&A...608A..89M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Stars, metal-deficient ; Spectroscopy ; Abundances ; Models, atmosphere ; Galaxies, nearby Keywords: line: formation - nuclear reactions, nucleosynthesis, abundances - stars: abundances - stars: atmospheres - galaxies: abundances - galaxies: dwarf Abstract: We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, -4≤[Fe/H]≲-2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo. Our results are based on high-resolution spectroscopic datasets and homogeneous and accurate atmospheric parameters determined in Paper I. We show that once the NLTE effects are properly taken into account, all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [alpha/Fe]=0.3 for each of the alpha-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in alpha/Fe with increasing metallicity in the Bootes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. The dichotomy in the [Sr/Ba] versus [Ba/H] diagram is observed in the classical dSphs, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr. We show that Sr in the massive galaxies is better correlated with Mg than Fe and that its origin is essentially independent of Ba, for most of the [Ba/H] range. Our three UFDs, that is Bootes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg]=-1.3 and [Ba/Mg]=-1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Bootes I and UMa II indicate a common r-process origin of their neutron-capture elements. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H]←2, is the strongest. Description: Tables 3 and 4 from the article are presented. They include the LTE and NLTE abundances from individual lines and average abundances of the investigated stars in the dSphs Sculptor (Scl), Ursa Minor (UMi), Fornax (Fnx), Sextans (Sex), Bootes I (Boo), UMa II, and Leo IV and the Milky Way (MW) halo. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file sources.dat 65 59 Sample stars table3.dat 62 4717 LTE and NLTE abundances from individual lines in the sample stars table4.dat 76 646 Summary of the LTE and NLTE abundances of the investigated stars
See also: J/A+A/604/A129 : Formation of MW halo and its dwarf satellites (Mashonkina+, J/AJ/144/168 : Spectroscopy of Scl 1019417 and UMi 20103 (Kirby+, 2012) J/ApJ/802/93 : 5 stars in Sculptor chemical abundance analysis (Simon+, 2015) J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010) J/ApJ/763/61 : Abundances of 7 red giant members of BootesI (Gilmore+, 2013) J/ApJ/711/350 : Metal-poor giant Boo-1137 abundances (Norris+, 2010) J/ApJ/826/110 : Boo-127 and Boo-980 high-resolution spectra (Frebel+, 2016) J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010) J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013) J/A+A/516/A46 : HE 2327-5642 abundance analysis (Mashonkina+, 2010) J/A+A/569/A43 : HE 2252-4225 abundance analysis (Mashonkina+, 2014) J/A+A/604/A129 : Formation of MW halo and its dwarf satellites (Mashonkina+, 2017) Byte-by-byte Description of file: sources.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Star Star designation 16- 17 I2 h RAh Right ascension (J2000) 19- 20 I2 min RAm Right ascension (J2000) 22- 26 F5.2 s RAs Right ascension (J2000) 28 A1 --- DE- Declination sign (J2000) 29- 30 I2 deg DEd Declination (J2000) 32- 33 I2 arcmin DEm Declination (J2000) 35- 38 F4.1 arcsec DEs Declination (J2000) 42- 65 A24 --- SName Simbad name
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Star Star designation 14- 15 A2 --- El Atom 17- 18 A2 --- Ion Ion 20- 26 F7.2 0.1nm lambda Wavelength 28- 31 F4.2 eV Eexc Excitation energy 33- 37 F5.2 --- loggf Adopted gf-value 39- 44 F6.3 rad/s/cm3 G6/NH van der Waals damping constant log(G6/NH) at 10000K 46- 50 F5.1 0.1pm EW ?=-1 Equivalent width (-1 means using spectral synthesis) 52- 56 F5.2 --- epsLTE LTE abundance (logeps(H)=12) 58- 62 F5.2 --- epsNLTE ? NLTE abundance (logeps(H)=12)
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Star Star designation 14- 15 I2 --- Nel Atomic number 17- 18 A2 --- El Atom 20- 21 A2 --- Ion Ion 23- 24 I2 --- Nlin Number of lines 26- 30 F5.2 --- epsLTE ? LTE abundance (logeps(H)=12) 32- 35 F4.2 --- e_epsLTE ? LTE abundance dispersion 37- 41 F5.2 [Sun] [El/H] ? LTE abundance [El/H] 43- 47 F5.2 [Sun] [El/Fe] ? LTE abundance [El/Fe] 49- 53 F5.2 --- epsNLTE ? NLTE abundance (logeps(H)=12) 55- 58 F4.2 --- e_epsNLTE ? NLTE abundance dispersion 60- 64 F5.2 [Sun] [El/Fe]N ? NLTE abundance [El/Fe] 66- 76 A11 --- Method Method of analysis (1)
Note (1): Wobs - equivalent widths method using data from references: CCT13 = Cohen et al. (2013, Cat. J/ApJ/778/56) CH10 = Cohen & Huang (2010, Cat. J/ApJ/719/931) FNG16 = Frebel et al. (2016, Cat. J/ApJ/826/110) FSG10 = Frebel et al. (2010, Cat. J/ApJ/708/560) GNM13 = Gilmore et al. (2013, Cat. J/ApJ/763/61) JNM15 = Jablonka et al. (2015A&A...583A..67J) KC12 = Kirby & Cohen (2012, Cat. J/AJ/144/168) NYG10 = Norris et al. (2010, Cat. J/ApJ/711/350) SFM10 = Simon et al. (2010ApJ...716..446S) SJF15 = Simon et al. (2015, Cat. J/ApJ/802/93) TJH10 = Tafelmeyer et al. (2010A&A...524A..58T) UCK15 = Ural et al. (2015MNRAS.449..761U) syn = synthetic spectrum method
Acknowledgements: Liudmila Mashonkina, lima(at)inasan.ru References: Mashonkina et al., Paper I 2017A&A...604A.129M, Cat. J/A+A/604/A129
(End) Yury Pakhomov [INASAN, Russia], Patricia Vannier [CDS] 17-Oct-2017
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

catalogue service

© UDS/CNRS

Contact