J/MNRAS/440/2665 SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014) ================================================================================ Detailed abundance analysis of the brightest star in Segue 2, the least massive galaxy. Roederer I.U., Kirby E.N. =2014MNRAS.440.2665R (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Stars, giant ; Spectroscopy Keywords: nuclear reactions, nucleosynthesis, abundances - stars: abundances - stars: individual: SDSS J021933.13+200830.2 - galaxies: individual: Segue 2 Abstract: We present the first high-resolution spectroscopic observations of one red giant star in the ultra-faint dwarf galaxy Segue 2, which has the lowest total mass (including dark matter) estimated for any known galaxy. These observations were made using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the Magellan II Telescope at Las Campanas Observatory. We perform a standard abundance analysis of this star, SDSS J021933.13+200830.2, and present abundances of 21 species of 18 elements as well as upper limits for 25 additional species. We derive [Fe/H]=-2.9, in excellent agreement with previous estimates from medium-resolution spectroscopy. Our main result is that this star bears the chemical signatures commonly found in field stars of similar metallicity. The heavy elements produced by neutron-capture reactions are present, but they are deficient at levels characteristic of stars in other ultra-faint dwarf galaxies and a few luminous dwarf galaxies. The otherwise normal abundance patterns suggest that the gas from which this star formed was enriched by metals from multiple Type II supernovae reflecting a relatively well-sampled IMF. This adds to the growing body of evidence indicating that Segue 2 may have been substantially more massive in the past. Description: Observations were made with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5 m Landon Clay Telescope (Magellan II) at Las Campanas Observatory. Objects: ---------------------------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------------------------- 02 19 33.14 +20 08 30.3 SDSS J021933.13+200830.2 = 2MASS J02193313+2008303 ---------------------------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 46 257 Atomic data, equivalent widths, and derived abundances -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 A5 --- ID Species (1) 7- 13 F7.2 0.1nm Wave Wavelength 15- 18 F4.2 eV ExPot Excitation potential 20- 24 F5.2 --- loggf Log of degeneracy times oscillator strength 26- 27 I2 --- Ref Literature reference for loggf (2) 29- 33 F5.1 10-13m EW ? Equivalent width 35 A1 --- l_logeps ? Upper limit flag on logeps 37- 41 F5.2 [-] logeps Log epsilon abundance 43- 46 F4.2 [-] e_logeps ? Error on log epsilon abundance -------------------------------------------------------------------------------- Note (1): Entries for CH and CN molecules have been omitted from this machine-readable table and are hereafter (from printed version): ------------------------------------------------------------------ Species Band Ref logeps ------------------------------------------------------------------ C (CH) A^2^{Delta}-X^2^{Pi} G band 2 4.85+/-0.20 N (CN) B^2^{Sigma}-X^2^{Sigma} violet band 3 <6.85 N (CN) A^2^{Sigma}-X^2^{Sigma} red band 3 <9.00 ------------------------------------------------------------------ Note (2): References as follows: 1 = Smith, Lambert, & Nissen (1998ApJ...506..405S) for both log gf value and 7Li hfs 2 = B. Plez 2007, private communication 3 = Kurucz & Bell (1995, Kurucz CD-ROM. Smithsonian Astrophysical Observatory. Cambridge, MA) 4 = Fuhr & Wiese (2009, Atomic Transition Probabilities. Handbook of Chemistry and Physics. 90th edn. Lide D. R., editor. Boca Raton, FL: CRC Press, Inc., p. 10) 5 = Chang & Tang (1990, J. Quant. Spectrosc. Rad. Trans., 43, 207) 6 = Aldenius et al. (2007A&A...461..767A) 7 = Aldenius, Lundberg, & Blackwell-Whitehead (2009A&A...502..989A) 8 = Lawler & Dakin (1989, J., Opt., Soc., Am., B Optical Phys., 6, 1457), using hfs from Kurucz & Bell (1995, Kurucz CD-ROM. Smithsonian Astrophysical Observatory. Cambridge, MA) 9 = Lawler et al. (2013ApJS..205...11L) 10 = Pickering, Thorne, & Perez (2001ApJS..132..403P), with corrections given in Pickering, Thorne, & Perez (2002, ApJS, 138, 247) 11 = Wood et al. (2013, Cat. J/ApJS/208/27) 12 = Doerr et al. (1985, J. Quant. Spectrosc. Rad. Trans., 33,55), using hfs from Kurucz & Bell (1995, Kurucz CD-ROM. Smithsonian Astrophysical Observatory. Cambridge, MA) 13 = Biemont et al. (1989A&A...209..391B) 14 = Sobeck, Lawler, & Sneden (2007, Cat. J/ApJ/667/1267) 15 = Nilsson et al. (2006A&A...445.1165N) 16 = Den Hartog et al. (2011. Cat. J/ApJS/194/35) for both log gf value and hfs 17 = O'Brian et al. (1991, J., Opt., Soc., Am., B Optical Phys, 8, 1185) 18 = Nitz et al. (1999ApJS..122..557N), using hfs from Kurucz & Bell (1995, Kurucz CD-ROM. Smithsonian Astrophysical Observatory. Cambridge, MA) 19 = Fuhr & Wiese (2009, Atomic Transition Probabilities. Handbook of Chemistry and Physics. 90th edn. Lide D. R., editor. Boca Raton, FL: CRC Press, Inc., p. 10), using hfs from Kurucz & Bell (1995, Kurucz CD-ROM. Smithsonian Astrophysical Observatory. Cambridge, MA) 20 = Roederer & Lawler (2012, Cat. J/ApJ/750/76) 21 = Biemont et al. (2011MNRAS.414.3350B) 22 = Ljung et al. (2006A&A...456.1181L) 23 = Palmeri et al. (2005MNRAS.363..452P) 24 = Fuhr & Wiese (2009, Atomic Transition Probabilities. Handbook of Chemistry and Physics. 90th edn. Lide D. R., editor. Boca Raton, FL: CRC Press, Inc., p. 10), using hfs/IS from McWilliam (1998AJ....115.1640M) when available 25 = Lawler, Bonvallet, & Sneden (2001ApJ...556..452L), using hfs from Ivans et al. (2006, Cat. J/ApJ/645/613) 26 = Lawler et al. (2009, Cat. J/ApJS/182/51) 27 = Li et al. (2007, J. Phys. Scr., 76, 577) using hfs from Sneden et al. (2009, Cat. J/ApJS/182/80) 28 = Den Hartog et al. (2003ApJS..148..543D), using hfs/IS from Roederer et al. (2008ApJ...675..723R) when available 29 = Lawler et al. (2006, Cat. J/ApJS/162/227) using hfs/IS from Roederer et al. (2008ApJ...675..723R) when available 30 = Lawler et al. (2001ApJ...556..452L), using hfs/IS from Ivans et al. (2006, Cat. J/ApJ/645/613) 31 = Den Hartog et al. (2006 , Cat. J/ApJS/167/292) 32 = Roederer et al. (2012ApJS..203...27R) 33 = Lawler et al. (2001ApJS..137..351L), using hfs from Lawler, Wyart, & Blaise (2001ApJS..137..351L) when available 34 = Wickliffe, Lawler, & Nave (2000, J. Quant. Spectrosc. Rad. Trans., 66, 363) 35 = Lawler, Sneden, & Cowan (2004ApJ...604..850L) for both log gf value and hfs 36 = Lawler et al. (2008ApJS..178...71L) 37 = Wickliffe & Lawler (1997, J., Opt., Soc., Am., B Optical Phys., 14, 737) 38 = Sneden et al. (2009, Cat. J/ApJS/182/80) for both log gf value and hfs/IS 39 = Lawler et al. (2007, Cat. J/ApJS/169/120) 40 = Ivarsson et al. (2003A&A...409.1141I), using hfs/IS from Cowan et al. (2005ApJ...627..238C), see note on log gf values there 41 = Biemont et al. (2000MNRAS.312..116B), using hfs/IS from Roederer et al. (2012, Cat. J/ApJ/750/76) -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 31-Jul-2015