Homogeneous Photometry for Star Clusters and Resolved Galaxies. I. A Survey of Bright Stars in the Fornax Dwarf Spheroidal Galaxy

Stetson, P. B.; Hesser, J. E.; Smecker-Hane, T.

doi:10.1086/316164

Cited by 153 publications

(260 citation statements)

References 49 publications

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“…The unit of the colorbar is stars per (100 pixel) 2 . 118 S. Lianou, E. Grebel & A. Koch behaviour similar to what is observed for the LG dSphs (Battinelli & Demers 2004), while the majority of them appear to be more confined to the central regions (Stetson et al 1998).…”

supporting

confidence: 68%

Early-type dwarf galaxies in the M81 group

Lianou¹,

Grebel²,

Koch

2009

Proc. IAU

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Abstract. The M81 group is a highly interacting group consisting of a few large galaxies and about 40 dwarfs of both early-and late-type, thus making it an important nearby laboratory to study environmental effects and the role of interactions in the formation and evolution of dwarf galaxies. We are studying the resolved stellar populations of the early-type dwarf galaxies in this group with available HST/ACS data. We will show results on the metallicity distribution functions and on the potential presence of population gradients for these dwarf galaxies.

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supporting

confidence: 68%

Early-type dwarf galaxies in the M81 group

Lianou¹,

Grebel²,

Koch

2009

Proc. IAU

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“…This cluster lies considerably farther from the galactic plane at b = À23 than does M71, hence field-star contamination is a much less serious problem for M5. The photometric database of Stetson, Hesser, & Smecker-Hane (1998) and Stetson (2000), which is described in considerable detail in Cohen et al (2002), was used to verify that the selected stars lie on the cluster locus in various color-magnitude diagrams. For the more luminous stars, we required the assignment of a high probability of membership by Cudworth (1979) in his proper-motion survey of this globular cluster.…”

Section: Stellar Samplementioning

confidence: 99%

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Ramírez

Cohen

2003

The Astronomical Journal

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We present the iron abundance and abundance ratios for 18 elements with respect to Fe in a sample of stars with a wide range in luminosity, from luminous giants to stars near the turnoff in the globular cluster M5. The analyzed spectra, obtained with the High Resolution Echelle Spectrograph at the Keck Observatory, are of high dispersion (R = /D = 35,000). We find that the neutron capture, the iron peak, and the -element abundance ratios show no trend with T eff and low scatter around the mean between the top of the red giant branch and near the main-sequence turnoff, suggesting that at this metallicity non-LTE effects are not important over the range of stellar parameters spanned by our sample. To within the precision of the measurements (about AE0.1 dex), gravitationally induced heavy-element diffusion does not appear to be present among the stars near the main-sequence turnoff studied here. Our work and other recent studies suggest that heavy-element diffusion is inhibited in the surface layers of metal-poor stars. Differences in the Na abundance from star to star that extend to the main-sequence turnoff are detected in our sample in M5. The anticorrelation between O and Na abundances, observed in other metal-poor globular clusters, is not detected in our sample, but it may be hidden among stars with only upper limits for their O abundances. As we found in M71, there is a hint of star-to-star variation in the Zr abundance. Overall the abundance ratios of M5 appear very similar to those of M71, with the possible exception of the neutron capture element Ba, for which we argue that the apparent difference may be due to difficulties in the analysis. As in M71, the -elements Mg, Ca, Si, and Ti are overabundant relative to Fe. The results of our abundance analysis of 25 stars in M5 provide further evidence of abundance variations among specific light elements at unexpectedly low luminosities, which cannot be explained by our current understanding of stellar evolution.

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“…They are not currently forming stars and show prominent old stellar populations, but their star formation histories (SFHs) are not uniformly old (see the recent reviews of Tolstoy et al 2009;Weisz et al 2014). Indeed, dSphs show a wide variety of SFHs; from systems that essentially completed forming their stars ∼ 10 Gyr ago, like Cetus and Draco (Monelli et al 2010;Aparicio et al 2001) to others where star formation was sustained over a long time and ceased only as recently as 6 Gyr ago (e.g., Leo II, Dolphin 2002) or even < 1 Gyr ago (e.g., Fornax, Stetson et al 1998;Saviane et al 2000;Battaglia et al 2006;de Boer et al 2012, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Mergers and the outside-in formation of dwarf spheroidals

Benítez-Llambay¹,

Navarro²,

Abadi³

et al. 2015

Mon. Not. R. Astron. Soc.

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We use a cosmological simulation of the formation of the Local Group to explore the origin of age and metallicity gradients in dwarf spheroidal galaxies. We find that a number of simulated dwarfs form "outside-in", with an old, metal-poor population that surrounds a younger, more concentrated metal-rich component, reminiscent of dwarf spheroidals like Sculptor or Sextans. We focus on a few examples where stars form in two populations distinct in age in order to elucidate the origin of these gradients. The spatial distributions of the two components reflect their diverse origin; the old stellar component is assembled through mergers, but the young population forms largely in situ. The older component results from a first episode of star formation that begins early but is quickly shut off by the combined effects of stellar feedback and reionization. The younger component forms when a late accretion event adds gas and reignites star formation. The effect of mergers is to disperse the old stellar population, increasing their radius and decreasing their central density relative to the young population. We argue that dwarf-dwarf mergers offer a plausible scenario for the formation of systems with multiple distinct populations and, more generally, for the origin of age and metallicity gradients in dwarf spheroidals.

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Homogeneous Photometry for Star Clusters and Resolved Galaxies. I. A Survey of Bright Stars in the Fornax Dwarf Spheroidal Galaxy

Cited by 153 publications

References 49 publications

Early-type dwarf galaxies in the M81 group

Early-type dwarf galaxies in the M81 group

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Mergers and the outside-in formation of dwarf spheroidals

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