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Properties of spectroscopically confirmed globular clusters in dwarf galaxies  sme@sao.ru

12 Questions on Star and Massive Star Cluster Formation, Garching (Germany), 2007. Sharina M.E., Puzia T.H. Properties of spectroscopically confirmed globular clusters in dwarf galaxies  sme@sao.ru. Low Surface Brightness Dwarf galaxies. Irregular include young stars. Spheroidal

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Properties of spectroscopically confirmed globular clusters in dwarf galaxies  sme@sao.ru

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  1. 12 Questions on Star and Massive Star Cluster Formation, Garching (Germany), 2007 Sharina M.E., Puzia T.H. Properties of spectroscopically confirmed globular clusters in dwarf galaxies  sme@sao.ru

  2. Low Surface Brightness Dwarf galaxies Irregular include young stars Spheroidal old and intermediate age stars Globular clusters offer an important tool to access star formation histories of their host galaxies 2

  3. 56 nearby (D = 2 - 6 Mpc) LSB dwarf galaxies (-10 > Mv > -16) were searched for globular clusters using HST WFPC2 imaging in V and I. We found that ~50% of galaxies contain globular cluster candidates. Sharina, Puzia, & Makarov ( A&A 442, 85, 2005 ) 3

  4. Spectra of globular clusters taken at the resolution < 1 nm Measurements of absorption line Lick indices Passband definitions: Worthey 94 flux in the feature flux in the continuum Determination of ages, metallicities and [a/Fe] ratios for the studied globular clusters We use the SSP model predictions of Thomas, Maraston and Bender (2003) 4

  5. V VLT MXU observations Distance to the main distributor (Mpc) D MD KK84 0.03 N3115 KK211 0.25 Cent A KK221 0.50 Cent A 5

  6. Diagnostic plot for GGs in KK84 (solid circles), KK211 (diamond), KK221 (o), E490-17 (triangle), UGC3755 (stars). SSP model predictions by Thomas et al. (2003). 6

  7. Diagnostic plot for GCs in KK84 (solid circles), KK211 (diamond), KK221 (o), E490-17 (triangle), UGC3755 (stars). SSP model predictions by Thomas et al. (2003). 7

  8. 8 All our sample GCs have low metallicity [Z/H]<1.2 dex, exept 2 (36n and 666) near NGC3115. Our sample GCs show [a/Fe]~0.1 dex, except GCs in KK84. Age of ~1 Gyr for 3 Gcs in UGC3577, ~4 Gyr for the nucleus of KK211 and 3 GCs in dIrrs, ~8 – 10 Gyr for GCs in dSphs and 3 GCs in dIrrs. Kuntschner et al. 02: GCs in N3115 with [Fe/H]=-0.4 and -1.36 dex, age 12 Gyr, [a/Fe]=0.3 dex. Norris et al. 06: [a/Fe]=0.2 , age=6 Gyr for the disk, and [a/Fe]=0.3 , age=12 Gyr for spheroid. Peng et al. 04: GCs in N5128 with [m/H]<-1.1 age 10-13Gyr, GCs with [m/H]=-0.1 age ~5 Gyr.

  9. Properties of galaxies studied with the 6m telescope Name MB AB Dist. DMD MD Type Environment (mag) (Mpc) Sextans B -14.0 0.14 1.36 1.36 MW dIrr isolated DDO71 -12.1 0.41 3.50 0.21 M81 dSph M81 gr. HolmbergIX -13.7 0.35 3.70 0.07 M81 dIrr, tidal M81 gr. IC10 -15.6 3.65 0.66 0.25 MW dIrr, WR Local gr. “Catalog of neighbouring galaxies”, Karachentsev et al. (2004) 9

  10. Dwarf galaxies in the M81 group(distance ~ 4 Mpc) dIrr tidal dwarf galaxy HolmbergIX dSph galaxy KDG63 10

  11. SSP model predictions: Thomas et al. (2003) 11

  12. SSP model predictions: Thomas et al. (2003) 12

  13. , dSphs The masses were obtained using Bruzual and Charlot (2003) SSP models with the Salpeter IMF. Ages and [Z/H] for GCs in NGC205, NGC147, and NGC185 were taken from Sharina, Afanasiev and Puzia, 2006. 13

  14. S vs. luminosity for galaxies from Durrell et al. 96, Harris 91 and our sample. Blue line shows the model of McLaughlin, 99. Green line shows S~mass^(-5/3), which follows from the model of mass loss by Dekel & Woo 03, M/L~M^(2/3). 14

  15. Conclusions: [a/Fe]~0 dex for GCs in dwarf galaxies (DwG).(Note that [a/Fe]~0.3 for GCs in spirals, [a/Fe]~0.5 for GCs in very massive galaxies, e.g. Puzia et al., 2006). Younger ages for old GGs in DwG (~10 Gyr) in comparison to giant galaxies. Younger mean ages of GCs in dIrs in comparison to dSphs. Low metallicity of GCs in DwG ([Z/H]<1.2 dex). Higher specific frequencies for GCs in dSphsin comparison todIrs. Masses and projected core radii (r_c) of GCs in DwG within the values typical for Galactic GCs. sme@sao.ru 15

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