J/A+A/604/A129 Formation of MW halo and its dwarf satellites (Mashonkina+, 2017)
The formation of the Milky Way halo and its dwarf satellites, a NLTE-1D
abundance analysis.
I. Homogeneous set of atmospheric parameters.
Mashonkina L., Jablonka P., Pakhomov Yu, Sitnova T, North P.
<Astron. Astrophys. 604, A129 (2017)>
=2017A&A...604A.129M 2017A&A...604A.129M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Stars, metal-deficient ; Spectroscopy ;
Abundances ; Models, atmosphere ; Galaxies, nearby
Keywords: stars: abundances - stars: atmospheres -
stars: fundamental parameters - galaxies: dwarf - Local Group
Abstract:
We present a homogeneous set of accurate atmospheric parameters for a
complete sample of very and extremely metal-poor stars in the dwarf
spheroidal galaxies (dSphs) Sculptor, Ursa Minor, Sextans, Fornax,
Bootes I, Ursa Major II, and Leo IV. We also deliver a Milky Way (MW)
comparison sample of giant stars covering the -4<[Fe/H]←1.7
metallicity range.
We show that, in the [Fe/H]=>-3.7 regime, the non-local thermodynamic
equilibrium (NLTE) calculations with non-spectroscopic effective
temperature (Teff) and surface gravity (log g) based on the
photometric methods and known distance provide consistent abundances
of the FeI and FeII lines. This justifies the FeI/FeII ionisation
equilibrium method to determine log g for the MW halo giants with
unknown distance.
The atmospheric parameters of the dSphs and MW stars were checked with
independent methods. In the [Fe/H]>-3.5 regime, the TiI/TiII
ionisation equilibrium is fulfilled in the NLTE calculations. In the
logg-Teff plane, all the stars sit on the giant branch of the
evolutionary tracks corresponding to [Fe/H]=-2 to -4, in line with
their metallicities. For some of the most metal-poor stars of our
sample, we hardly achieve consistent NLTE abundances from the two
ionisation stages for both iron and titanium. We suggest that this is
a consequence of the uncertainty in the Teff-colour relation at those
metallicities. The results of these work provide the base for a
detailed abundance analysis presented in a companion paper.
Description:
Tables A.1 and A.2 from the article are presented. The first table
contains atomic parameters of FeI/II and TiI/II lines. The second
atmospheric parameters and FeI/II, TiI/II nLTE abundances.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 31 197 Line data
tablea2.dat 92 59 Iron and titanium NLTE abundances for the
investigated sample
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See also:
J/AJ/144/168 : Spectroscopy of Scl 1019417 and UMi 20103 (Kirby+, 2012)
J/ApJ/802/93 : Chemical abundance analysis of 5 stars in Sculptor
(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/608/A89 : Formation of MW halo and its dw satellites. II.
(Mashonkina+, 2017)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- El Atom
4- 5 A2 --- Ion Ion
7- 13 F7.2 0.1nm lambda Wavelength
15- 18 F4.2 eV Eexc Excitation energy
20- 24 F5.2 --- loggf Adopted gf-value
26- 31 F6.3 rad/s/cm3 G6/NH van der Waals damping constant log(G6/NH)
at 10000K
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ID Star ID
14- 17 I4 K Teff Effective temperature
19- 22 F4.2 [cm/s2] logg Surface gravity
24- 28 F5.2 --- [Fe/H] Metallicity
30- 32 F3.1 km/s Vt Microturbulent velocity
36- 39 F4.2 --- epsFeI FeI NLTE abundance (log eps(H)=12)
41- 44 F4.2 --- e_FeI FeI NLTE abundance dispersion (sigma(log eps))
46- 47 I2 --- o_FeI Number of FeI lines
51- 54 F4.2 --- epsFeII FeII NLTE abundance (log eps(H)=12)
56- 59 F4.2 --- e_FeII FeII NLTE abundance dispersion (sigma(log eps))
61- 62 I2 --- o_FeII Number of FeII lines
66- 69 F4.2 --- epsTiI ? TiI NLTE abundance (log eps(H)=12)
71- 74 F4.2 --- e_TiI ? TiI NLTE abundance dispersion (sigma(log eps))
76- 77 I2 --- o_TiI ? Number of TiI lines
81- 84 F4.2 --- epsTiII TiII NLTE abundance (log eps(H)=12)
86- 89 F4.2 --- e_TiII TiII NLTE abundance dispersion (sigma(log eps))
91- 92 I2 --- o_TiII Number of TiII lines
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Acknowledgements:
Yury Pakhomov, pakhomov(at)inasan.ru
References:
Mashonkina et al., Paper II 2017A&A...608A..89M 2017A&A...608A..89M, Cat. J/A+A/608/A89
(End) Yury Pakhomov [INASAN, Russia], Patricia Vannier [CDS] 26-Apr-2017