1. An Abundance Spread in the Bootes I Dwarf Spheroidal Galaxy? John E. Norris The Australian National University Gerard Gilmore University of Cambridge R.F.G. Wyse Johns Hopkins University The

2. Belokurov et al. 2006 ApJ, 647, L111; 2007 ApJ, 654, 897 M71  Cen M v = -5.8 r h = 230 pc (13 arcmin) Distance = 60 kpc [Fe/H] = -2.5

3. Mass enclosed within stellar extent ~ 4 x 10 7 M   Globular star clusters, no DM  Gilmore et al 2007 ApJ, 663, 948

5. Bootes I with AAT/AAOMEGA

6. Bootes I : Radial velocity vs Radial distance

7. Bootes I : C4150 > 200 cnts/pix, Radial vel. vs Radial dist.

8. Spectra of 15 radial velocity members of Bootes I g 0 /(g-r) 0 /[Fe/H]

9. Bootes I compared with M15 Bootes IM15 (B-V) 0 /[Fe/H]

10. Boo-1137 versus extremely metal-poor stars

11. Bootes I: Ca II Triplet vs Ca II K

19. Helmi et al 2006 ApJ, 651, L121

20. We have isolated a sample of 16 putative radial velocity RGB members of the low-luminosity Bootes I dSph galaxy (90 < V r < 115 km/s) In this sample there is an abundance range of  [Fe/H] ~ 2 dex, with one star having [Fe/H = -3.5 The abundance dispersion is  ([Fe/H]) = 0.4 +/- 0.1, which is of the same order as those of the Galaxy’s more luminous dSph systems, and  Centauri This suggests that the large mass (> 10 7 M o ) normally assumed to foster the production of abundance spreads of the  - and iron-peak elements was provided by the non-baryonic material in Bootes I. SUMMARY