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J/MNRAS/449/761  EWs of metal-poor stars in the UMi I dSph galaxy  (Ural+, 2015)

An inefficient dwarf: chemical abundances and the evolution of the Ursa Minor dwarf spheroidal galaxy. Ural U., Cescutti G., Koch A., Kleyna J., Feltzing S., Wilkinson M.I. <Mon. Not. R. Astron. Soc., 449, 761-770 (2015)> =2015MNRAS.449..761U (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, metal-deficient ; Equivalent widths Keywords: galaxies: abundances - galaxies: dwarf - galaxies: evolution - galaxies: individual: UMi I dSph - Local Group Abstract: We present detailed chemical element abundance ratios of 17 elements with eight≤Z≤60 in three metal-poor stars in the Ursa Minor dwarf spheroidal galaxy, which we combine with extant data from the literature to assess the predictions of a novel suite of galaxy chemical evolution models. The spectroscopic data were obtained with the Keck/High-Resolution Echelle Spectrograph instrument and revealed low metallicities of [Fe/H]=-2.12, -2.13 and -2.67 dex. While the most metal-poor star in our sample shows an overabundance of [Mn/Fe] and other Fe-peak elements, our overall findings are in agreement with previous studies of this galaxy: elevated values of the [α/Fe] ratios that are similar to, or only slightly lower than, the halo values but with SN Ia enrichment at very low metallicity, as well as an enhancement of the ratio of first to second peak neutron capture elements [Y/Ba] with decreasing metallicity. The chemical evolution models which were tailored to reproduce the metallicity distribution function of the dwarf spheroidal, indicate that Ursa Minor had an extended star formation which lasted nearly 5 Gyr with low efficiency and are able to explain the [Y/Ba] enhancement at low metallicity for the first time. In particular, we show that the present-day lack of gas is probably due to continuous loss of gas from the system, which we model as winds. Description: The observations were made using the High-Resolution Echelle Spectrograph (HIRES; Vogt, Allen & Bigelow 1994SPIE.2198..362V) on the Keck telescope on the night of UT 2006-06-05. The targets were selected from legacy Kitt Peak National Observatory (KPNO) 4 m mosaic imaging as in Wilkinson, Kleyna & Evans (2004ApJ...611L..21W). Objects: ---------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------- 15 09 11.34 +67 12 51.7 UMi I dSph = NAME UMi Galaxy ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 81 3 Observed stars table2.dat 43 343 Equivalent width measurements
See also: J/AJ/90/2221 : UMi dwarf galaxy BV photometry (Olszewski+, 1985) J/AJ/110/2131 : M/L for Draco and UMi. I. (Armandroff+ 1995) J/AJ/124/3222 : VI photometry of Draco and UMi galaxies (Bellazzini+, 2002) J/AJ/125/1352 : Ursa Minor dSph M,T2, DDO51 photometry (Palma+, 2003) J/ApJ/617/L41 : Red giant variable candidates in UMi dSph (Mighell+, 2004) J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 A6 --- Star Target star name (UMINNN) 8- 12 F5.2 mag Imag Johnson-Cousins I-band magnitude from Kleyna et al. (1998AJ....115.2359K) 14- 18 F5.2 mag Vmag Johnson-Cousins V-band magnitude from Kleyna et al. (1998AJ....115.2359K) 20- 25 F6.3 mag Kmag 2MASS K-band magnitude 27- 28 I2 h RAh Hour of Right Ascension (J2000) 30- 31 I2 min RAm Minute of Right Ascension (J2000) 33- 37 F5.2 s RAs Second of Right Ascension (J2000) 38 A1 --- DE- Sign of the Declination (J2000) 39- 40 I2 deg DEd Degree of Declination (J2000) 42- 43 I2 arcmin DEm Arcminute of Declination (J2000) 45- 49 F5.2 arcsec DEs Arcsecond of Declination (J2000) 51- 54 I4 K Teffph Photometric effective temperature from (V-I) (1) 56- 59 I4 K Teffs Spectroscopic effective temperature (2) 61- 63 F3.1 [cm/s2] logg Surface gravity (1) (2) 65- 68 F4.2 km/s Vt Microturbulence velocity (2) 70- 74 F5.2 [-] [Fe/H] Metallicity (2) 76- 81 F6.1 km/s RV Radial velocity
Note (1): Calculated assuming a metallicity of [Fe/H]=-2 dex, mass of 0.8 M and distance of 68 kpc. Note (2): Values found by iteration of the best atmospheric models used to calculate the spectroscopic abundances (see the text for details).
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 A5 --- El Element 7- 13 F7.2 0.1nm lambda Wavelength of the absorption line λ (Å) 15- 18 F4.2 eV EP Excitation energy of the lower energy level 20- 25 F6.3 --- loggf Oscilator strength 27- 31 F5.1 0.1pm EW-UMI396 ? Equivalent width of the line measured for the star UMI396 (mÅ) 33- 37 F5.1 0.1pm EW-UMI718 ? Equivalent width of the line measured for the star UMI718 (mÅ) 39- 43 F5.1 0.1pm EW-UMI446 ? Equivalent width of the line measured for the star UMI446 (mÅ)
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 23-Jan-2018
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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