A New Look at Simple Inhomogeneous Chemical Evolution

Oey, M. S.

doi:10.1086/312921

Cited by 43 publications

(94 citation statements)

References 13 publications

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“…Numerous examples of such models can be found in the literature (e.g., Naab & Ostriker 2006;Romano et al 2006;Worthey et al 2005;Scannapieco et al 2005;Valle et al 2005;Lanfranchi & Matteucci 2004;Oey 2000, among many recent discussions). These have been developed all the way to full hierarchical-merging and chemodynamical-evolution codes (e.g., Kawata & Gibson 2003;Cole et al 2000;Beasley et al 2003;Somerville & Primack 1999).…”

Section: A Chemical Evolution Modelmentioning

confidence: 99%

Hubble Space TelescopePhotometry for the Halo Stars in the Leo Elliptical NGC 3377

Harris

Layden

et al. 2007

Astron J

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We have used the ACS camera on HST to obtain (V, I ) photometry for 57,000 red giant stars in the halo of the Leo elliptical NGC 3377, an intermediate-luminosity elliptical. We use this sample of stars to derive the metallicity distribution function (MDF ) for its halo field stars and comment on its chemical evolution history compared with both larger and smaller E galaxies. Our ACS WFC field spans a radial range extending from 4 to 18 kpc projected distance from the center of NGC 3377 and thus covers a significant portion of this galaxy's halo. We find that the MDF is broad, reaching a peak at log (Z/Z ) ' À0:6, but containing virtually no stars more metal-poor than log (Z /Z ) ¼ À1:5. It may, in addition, have relatively few stars more metal-rich than log (Z/Z ) ' À0:3, although interpretation of the high-metallicity end of the MDF is limited by photometric completeness that affects the detection of the reddest, most metal-rich stars. NGC 3377 appears to have an enrichment history intermediate between those of normal dwarf ellipticals and the much larger giants. As yet, we find no clear evidence that the halo of NGC 3377 contains a significant population of ''young'' (<3 Gyr) stars.

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Section: A Chemical Evolution Modelmentioning

confidence: 99%

Hubble Space TelescopePhotometry for the Halo Stars in the Leo Elliptical NGC 3377

Harris

Layden

et al. 2007

Astron J

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“…Adopting an average of n ∼ 5 × 10 4 , he suggested that fluctuations would be relatively small. More detailed models for overlapping contaminations were studied by Roy & Kunth (1995), Argast et al (2000) and Oey (2000). Oey (2003) used turbulent dispersal from Bateman & Larson (1993) to enlarge the effective sizes and reduce the average metallicities in the overlapping regions.…”

Section: How Large Should Metallicity Fluctuations Be?mentioning

confidence: 99%

Interstellar Turbulence II: Implications and Effects

Scalo

Elmegreen

2004

Annu. Rev. Astron. Astrophys.

309

157

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Interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium. This review discusses the observations and theory of these effects. Metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed. Modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed. Interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii. Radio wave scintillation is an important diagnostic for small scale turbulence in the ionized medium, giving information about the power spectrum and amplitude of fluctuations. The theory of diffraction and refraction is reviewed, as are the main observations and scintillation regions.

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“…This question leads us to another: What are the number and the metallicities of stars enriched by any given number of SNe? Several chemical evolution models have been developed to study the effect of small number statistics on the build-up of chemical elements in the early Galaxy (e.g., Tsujimoto et al 1999;Argast et al 2000;Oey 2000;Travaglio et al 2001). However, these models do not explicitly trace or discuss the metallicity distributions of individual populations of stars enriched by a specific number of SNe.…”

Section: Introductionmentioning

confidence: 99%

Stochastic chemical enrichment in metal-poor systems

Karlsson¹

2005

A&A

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Abstract.A stochastic model of the chemical enrichment of metal-poor systems by core-collapse (Type II) supernovae is presented, allowing for large-scale mixing of the enriched material by turbulent motions and cloud collisions in the interstellar medium. Infall of pristine material is taken into account by following the evolution of the gas density in the medium. Analytical expressions were derived for the number of stars enriched by a given number of supernovae, as well as for the amount of mass with which the ejected material from a supernova is mixed before being locked up in a subsequently formed star. It is shown that for reasonable values of the gas density (∼0.1 cm −3 ) and of the supernova rate (∼0.25 kpc −3 Myr −1 ) of the Galactic halo, the resulting metallicity distributions of the extreme Population II stars show a distinct cut-off at [Fe/H] −4. In fact, by assuming no low-mass Population III stars were able to form out of the primordial interstellar medium, the derived fraction of stars below [Fe/H] = −4 is in agreement with observations. Moreover, the probability is high that even the most metal-poor stars observed to date have been enriched by several contributing supernovae. This partly explains the relatively small starto-star scatter in many chemical abundance ratios for stars down to [Fe/H] = −4, as recently found in several observational studies. Contribution from the thermonuclear (Type Ia) supernovae is found to be negligible over almost the entire extremely metal-poor regime. Although the fraction of contaminated stars may increase rapidly towards [Fe/H] = −2.5, the fraction of stars with iron primarily from Type Ia supernovae remains small. The stars that are heavily polluted by Type Ia supernovae are pushed towards higher metallicities, creating a hole/bump in the metallicity distribution. Such features could be used to reveal the possible presence of subpopulations of Galactic halo stars that have been enriched by Type Ia supernovae.

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A New Look at Simple Inhomogeneous Chemical Evolution

Cited by 43 publications

References 13 publications

Hubble Space TelescopePhotometry for the Halo Stars in the Leo Elliptical NGC 3377

Hubble Space TelescopePhotometry for the Halo Stars in the Leo Elliptical NGC 3377

Interstellar Turbulence II: Implications and Effects

Stochastic chemical enrichment in metal-poor systems

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