J/ApJ/723/1632 Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)
Chemical enrichment in the faintest galaxies: the carbon and iron abundance spreads in the Bootes I dwarf spheroidal galaxy and the Segue 1 system. Norris J.E., Wyse R.F.G., Gilmore G., Yong D., Frebel A., Wilkinson M.I., Belokurov V., Zucker D.B. <Astrophys. J., 723, 1632-1650 (2010)> =2010ApJ...723.1632N
ADC_Keywords: Abundances ; Galaxies, nearby ; Photometry, SDSS ; Stars, giant ; Radial velocities Keywords: galaxies: abundances - galaxies: dwarf - stars: abundances - galaxies: individual (Bootes I, Segue 1) - Galaxy: abundances - Abstract: We present an AAOmega spectroscopic study of red giants in the ultra-faint dwarf galaxy Bootes I (MV~-6) and the Segue 1 system (MV~-1.5), either an extremely low luminosity dwarf galaxy or an unusually extended globular cluster. Both Bootes I and Segue 1 have significant abundance dispersions in iron and carbon. Bootes I has a mean abundance of [Fe/H]=-2.55±0.11 with an [Fe/H] dispersion of σ=0.37±0.08, and abundance spreads of Δ[Fe/H]=1.7 and Δ[C/H]=1.5. Segue 1 has a mean of [Fe/H]=-2.7±0.4 with [Fe/H] dispersion of σ=0.7±0.3, and abundances spreads of Δ[Fe/H]=1.6 and Δ[C/H]=1.2. Moreover, Segue 1 has a radial-velocity member at four half-light radii that is extremely metal-poor and carbon-rich, with [Fe/H]=-3.5, and [C/Fe]=+2.3. Modulo an unlikely non-member contamination, the [Fe/H] abundance dispersion confirms Segue 1 as the least-luminous ultra-faint dwarf galaxy known. Description: Candidate red giant members of Bootes I and Segue 1 were observed with the Anglo-Australian Telescope/AAOmega fiber-fed spectrograph combination during 2007 April 18-20 and 2006 May 23-29. Only the blue spectra from the 2007 data set are discussed in this paper. These spectra have resolution R=5000 and cover the wavelength range 3850-4540Å. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 64 122 Observational data and derived heliocentric velocities for stars in the Bootes I field table2.dat 64 134 Observational data and derived heliocentric velocities for stars in the Segue 1 field table3.dat 68 16 Observational data and derived atmospheric parameters for candidate member stars of Bootes I table4.dat 68 6 Observational data and derived atmospheric parameters for candidate member stars of Segue 1
See also: II/306 : The SDSS Photometric Catalog, Release 8 (Adelman-McCarthy+, 2011) J/ApJ/711/350 : Metal-poor giant Boo-1137 abundances (Norris+, 2010) J/ApJ/692/1464 : Spectroscopy of Segue 1 (Geha+, 2009) J/MNRAS/380/281 : Faint Galactic satellites survey (Martin+, 2007) J/AJ/117/981 : Estimation of stellar metal abundance. II. (Beers+, 1999) Byte-by-byte Description of file: table.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Seq Identification number 6- 7 I2 h RAh Hour of Right Ascension (J2000) 9- 10 I2 min RAm Minute of Right Ascension (J2000) 12- 16 F5.2 s RAs Second of Right Ascension (J2000) 18 A1 --- DE- [+] Sign of the Declination (J2000) 19- 20 I2 deg DEd Degree of Declination (J2000) 22- 23 I2 arcmin DEm Arcminute of Declination (J2000) 25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000) 30- 34 F5.2 mag gmag [17.25/21.49] SDSS-DR4 g band magnitude 36- 40 F5.2 mag imag SDSS-DR4 i band magnitude 42- 46 F5.1 arcmin Xpix X pixel location 48- 52 F5.1 arcmin Ypix Y pixel location 54- 57 F4.1 arcmin Rad [2.1/60] Radius from center 59- 62 I4 km/s HRV [-207/327] Heliocentric radial velocity 64 A1 --- Mem? [y/n] Candidate member? (1)
Note (1): Candidate radial-velocity members in Bootes I (table 1) lying within the range 85-130km/s (N=36 for "y"). Candidate radial-velocity members in Segue 1 (table 2) lying within the range 185-230km/s (N=9 for "y").
Byte-by-byte Description of file: table3.dat table4.dat
Bytes Format Units Label Explanations
1- 7 I7 --- Seq Star number 8 A1 --- f_Seq [cde] Question about membership (1) 10- 13 F4.1 arcmin Rad [2.1/48.8] Radius from center 15- 17 I3 km/s HRV [94/216] Heliocentric radial velocity 19- 23 F5.2 mag gmag [17.52/19.3] SDSS-DR4 g-band magnitude 25- 29 F5.3 mag (g-r)0 Corrected (g-r) color index 31- 35 F5.3 mag (r-z)0 ? Corrected (r-z) color index 37- 40 F4.2 0.1nm K' ? CaII K line-strength index (K') defined by Beers et al. (1999, Cat. J/AJ/117/981) 42- 45 I4 K Teff Effective temperature 47- 49 F3.1 [cm/s2] logg Surface gravity 51- 55 F5.2 [Sun] [Fe/H] ? Abundance of [Fe/H] 56 A1 --- f_[Fe/H] [abcgh] Origin of [Fe/H] (1) 58- 62 F5.2 [Sun] [C/H] ? Abundance of [C/H] 64- 68 F5.2 [Sun] [C/Fe] ? Abundance of [C/Fe]
Note (1): Flag as follows: a = From the new VLT/UVES high-resolution, high-S/N, data mentioned in the text. The abundance coincides with the value obtained from AAOmega moderate-resolution CaII K' data. b = From this work, based on AAOmega moderate-resolution CaII K' data. c = Likely non-member, though velocity matches systemic. See the text for discussion. d = Inconsistent blue and red abundances. See the text for discussion. e = RGB member from Geha et al. (2009, Cat. J/ApJ/692/1464), not observed by us. g = From G. Gilmore et al. (2010, in preparation), based on VLT/Flames/UVES data. h = From Norris et al. (2010, Cat. J/ApJ/711/350).
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 26-Jul-2012
|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|