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J/AJ/151/82 The 4 brightest red giants in the UFD galaxy Ret 2 (Roederer+, 2016)

Detailed chemical abundances in the r-process-rich ultra-faint dwarf galaxy Reticulum 2. Roederer I.U., Mateo M., Bailey III J.I., Song Y., Bell E.F., Crane J.D., Loebman S., Nidever D.L., Olszewski E.W., Shectman S.A., Thompson I.B., Valluri M., Walker M.G. <Astron. J., 151, 82 (2016)> =2016AJ....151...82R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, giant ; Photometry, ugriz ; Radial velocities ; Spectroscopy ; Equivalent widths ; Effective temperatures ; Abundances Keywords: galaxies: dwarf - galaxies: individual: Reticulum 2 - nuclear reactions, nucleosynthesis, abundances - stars: abundances Abstract: The ultra-faint dwarf (UFD) galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey (Diehl et al. 2014SPIE.9149E..0VD). We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/Magellan Fiber System. We present detailed abundances for as many as 20 elements per star, including 12 elements heavier than the Fe group. We confirm previous detection of high levels of r-process material in Ret 2 (mean [Eu/Fe]=+1.69±0.05) found in three of these stars (mean [Fe/H]=-2.88±0.10). The abundances closely match the r-process pattern found in the well-studied metal-poor halo star CS 22892-052. Such r-process-enhanced stars have not been found in any other UFD galaxy, though their existence has been predicted by at least one model. The fourth star in Ret 2 ([Fe/H]=-3.42±0.20) contains only trace amounts of Sr ([Sr/Fe]=-1.73±0.43) and no detectable heavier elements. One r-process enhanced star is also enhanced in C (natal [C/Fe]~+1.1). This is only the third such star known, which suggests that the nucleosynthesis sites leading to C and r-process enhancements are decoupled. The r-process-deficient star is enhanced in Mg ([Mg/Fe]=+0.81±0.14), and the other three stars show normal levels of α-enhancement (mean [Mg/Fe]=+0.34±0.03). The abundances of other α and Fe-group elements closely resemble those in UFD galaxies and metal-poor halo stars, suggesting that the nucleosynthesis that led to the large r-process enhancements either produced no light elements or produced light-element abundance signatures indistinguishable from normal supernovae. Description: There are only four stars brighter than the horizontal branch that are confirmed members of Ret 2 (Simon et al. 2015, J/ApJ/808/95; Walker et al. 2015, J/ApJ/808/108). We observed these four stars using one arm of the Michigan/Magellan Fiber System (M2FS) and MSpec double spectrograph (Bailey et al. 2012SPIE.8446E..5GB; Mateo et al. 2012SPIE.8446E..4YM) mounted on the Nasmyth platform at the 6.5 m Landon Clay Telescope (Magellan II) at Las Campanas Observatory, Chile. We observed four high-probability members of Ret 2 and one blank sky position simultaneously on 2015 November 14 and 16, with a total integration time of 6.67 hr. Both observations were taken in dark time. Objects: ------------------------------------------------------------- RA (ICRS) DE Designation(s) ------------------------------------------------------------- 03 35 42.1 -54 02 57 Reticulum 2 = NAME Reticulum II ------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 64 4 Basic Stellar Data table3.dat 59 207 Equivalent Widths and Atomic Data table4.dat 43 4 Stellar Parameters table5.dat 32 428 Abundances Derived from Individual Lines
See also: J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006) J/ApJS/162/227 : Transition probabilities for SmII (Lawler+, 2006) J/ApJS/167/292 : Laboratory transition probabilities for Gd II (Den Hartog+, 2006) J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007) J/ApJS/182/51 : Transition probabilities of rare earth elements (Lawler+, 2009) J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009) J/ApJS/194/35 : Atomic transition probabilities of Mn (Den Hartog+, 2011) J/ApJ/750/76 : r-process peaks elements in HD 160617 (Roederer+, 2012) J/ApJ/767/134 : Abundances of red giant stars in UFD galaxies (Vargas+, 2013) J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013) J/ApJS/211/20 : NiI transition probability measurements (Wood+, 2014) J/ApJS/215/20 : Vanadium log(gf) and transition probabilities (Lawler+, 2014) J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014) J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015) J/ApJ/808/108 : M2FS stellar spectroscopy of Reticulum 2 (Walker+, 2015) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [Star] 6 I1 --- Star [1/4] Star name from this work (Star N) 8- 10 A3 --- --- [DES] 12- 30 A19 --- DES Dark Energy Survey (DES, Diehl et al. 2014SPIE.9149E..0VD) star name from Simon et al. (2015, J/ApJ/808/95) (DES JHHMMSS.ss+DDMMSS.s) 32- 36 A5 --- --- [Ret2-] 37- 39 I3 --- Ret2- [80/178]? Star name from Walker et al. (2015, J/ApJ/808/108) (Ret2-NNN) 41- 45 F5.2 mag gmag [16.47/17.57] Star g-band magnitude, adopted from Koposov et al. (2015ApJ...805..130K) 47- 50 F4.2 mag g-r [0.56/0.80] Star g-r color, adopted from Koposov et al. (2015ApJ...805..130K) 52- 55 F4.1 km/s <HRV> [59.7/65.5] Mean calculated heliocentric radial velocity 57- 58 I2 --- S/N4300 [15/26] Spectral signal-to-noise ratio at 4300Å 60- 61 I2 --- S/N4800 [26/45] Spectral signal-to-noise ratio at 4800Å 63- 64 I2 --- S/N5200 [33/59] Spectral signal-to-noise ratio at 5200Å
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Ion Species 7- 13 F7.2 0.1nm Wave [4149.20/5429.70] Wavelength λ (Å) 15- 18 F4.2 eV ExPot [0.00/4.47] Excitation potential 20- 24 F5.2 [-] log(gf) [-5.62/0.65] Log of degeneracy times oscillator strength 26- 27 I2 --- r_log(gf) [1/29] Literature reference for log(gf) value (1) 29 A1 --- f_EW-1 [ls] Flag on EW-1 (2) 31- 35 F5.1 0.1pm EW-1 [17.7/144.7]? Equivalent width for Star 1 (mÅ) 37 A1 --- f_EW-2 [ls] Flag on EW-2 (2) 39- 43 F5.1 0.1pm EW-2 [21.3/238.1]? Equivalent width for Star 2 (mÅ) 45 A1 --- f_EW-3 [ls] Flag on EW-3 (2) 47- 51 F5.1 0.1pm EW-3 [6.4/190.3]? Equivalent width for Star 3 (mÅ) 53 A1 --- f_EW-4 [ls] Flag on EW-4 (2) 55- 59 F5.1 0.1pm EW-4 [8.4/220.3]? Equivalent width for Star 4 (mÅ)
Note (1): Reference as follows: 1 = NIST, Kramida et al. (2015, NIST Atomic Spectra Database (v. 5.3) online: http://physics.nist.gov/asd); 2 = Aldenius et al. (2007A&A...461..767A); 3 = Lawler & Dakin (1989JOSAB...6.1457L), using hyperfine splitting (HFS) from Kurucz & Bell (1995KurCD..23.....K); 4 = Lawler et al. (2013ApJS..205...11L); 5 = Wood et al. (2013, J/ApJS/208/27); 6 = Lawler et al. (2014, J/ApJS/215/20); 7 = Sobeck et al. (2007, J/ApJ/667/1267); 8 = Nilsson et al. (2006A&A...445.1165N); 9 = Booth et al. (1984MNRAS.208..147B); 10 = Den Hartog et al. (2011, J/ApJS/194/35) for both log(gf) value and HFS; 11 = Ruffoni et al. (2014, J/MNRAS/441/3127); 12 = Wood et al. (2014, J/ApJS/211/20); 13 = NIST, Kramida et al. (2015, NIST Atomic Spectra Database (v. 5.3) online: http://physics.nist.gov/asd), using HFS from Kurucz & Bell (1995KurCD..23.....K); 14 = Roederer & Lawler (2012, J/ApJ/750/76); 15 = Biemont et al. (2011MNRAS.414.3350B); 16 = Ljung et al. (2006A&A...456.1181L); 17 = Palmeri et al. (2005MNRAS.363..452P); 18 = Wickliffe et al. (1994JQSRT..51..545W); 19 = NIST, Kramida et al. (2015, NIST Atomic Spectra Database (v. 5.3) online: http://physics.nist.gov/asd), using HFS/isotope shifts (IS) from McWilliam (1998AJ....115.1640M) when available; 20 = Lawler et al. (2001ApJ...556..452L), using HFS from Ivans et al. (2006, J/ApJ/645/613); 21 = Lawler et al. (2009, J/ApJS/182/51); 22 = Li et al. (2007PhyS...76..577L), using HFS from Sneden et al. (2009, J/ApJS/182/80); 23 = Ivarsson et al. (2001PhyS...64..455I), using HFS from Sneden et al. (2009, J/ApJS/182/80); 24 = Den Hartog et al. (2003ApJS..148..543D), using HFS/IS from Roederer et al. (2008ApJ...675..723R) when available; 25 = Lawler et al. (2006, J/ApJS/162/227), using HFS/IS from Roederer et al. (2008ApJ...675..723R) when available; 26 = Lawler et al. (2001ApJ...563.1075L), using HFS/IS from Ivans et al. (2006, J/ApJ/645/613); 27 = Den Hartog et al. (2006, J/ApJS/167/292); 28 = Lawler et al. (2001ApJS..137..341L), using HFS from Lawler et al. (2001ApJS..137..351L) when available; 29 = Wickliffe et al. (2000JQSRT..66..363W). Note (2): Flag as follows: s = Indicates that abundances were derived by spectral synthesis matching; l = Indicates that an upper limit was derived from a non-detection.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [Star] 6 I1 --- Star [1/4] Star name from this work (Star N) 8- 11 I4 K Teff [4710/5020] Derived stellar effective temperature 13- 15 I3 K e_Teff [140] Uncertainty in Teff 17- 20 F4.2 [cm/s2] logg [1.22/2.09] Derived log of surface gravity 22- 25 F4.2 [cm/s2] e_logg [0.38/0.40] Uncertainty in logg 27- 30 F4.2 km/s Vt [2.00/2.85] Derived microturbulence velocity 32- 34 F3.1 km/s e_Vt [0.2/0.3] Uncertainty in Vt 36- 39 F4.1 [Sun] [M/H] [-3.3/-2.7] Model derived metallicity 41- 43 F3.1 [Sun] e_[M/H] [0.2] Uncertainty in [M/H]
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [Star] 6 I1 --- Star [1/4] Star name from this work (Star N) 8- 12 A5 --- Ion Species 14- 20 F7.2 0.1nm Wave [4149.20/5429.70] Wavelength λ (Å) 22 A1 --- l_logeps [<] Limit flag on logeps 23- 27 F5.2 [-] logeps [-2.59/5.35] Log ε abundance 29- 32 F4.2 [-] e_logeps [0.15/0.57]? Error on logeps
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 21-Mar-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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