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Rieschick, Andreas; Hensler, G.

doi:10.1023/a:1012720803748

Cited by 7 publications

(7 citation statements)

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“…This scenario naturally explains the uniform abundances found in dwarf galaxies, while ruling out local enrichment within the star-forming regions. It must be noted that models of Rieschick & Hensler (2001, 2003, based on Tenorio-Tagle's scenario, predict that only ∼75% of the SNe products go through the outer Article published by EDP Sciences galactic cycle as hot gas, while the remaining 25% evolve in an inner local cycle and can enrich the star-forming regions in only 10 Myr. A few percent could eventually leave the gravitational field of the galaxy.…”

Section: Introductionmentioning

confidence: 99%

Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

Lebouteiller¹,

Kunth

Thuan

et al. 2008

A&A

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Context. Evidence has grown over the past few years that the neutral phase of blue compact dwarf (BCD) galaxies may be metaldeficient as compared to the ionized gas of their H ii regions. These results have strong implications for our understanding of the chemical evolution of galaxies, and it is essential to strengthen the method, as well as to find possible explanations. Aims. We present the analysis of the interstellar spectrum of Pox 36 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Pox 36 was selected because of the relatively low foreground gas content that makes it possible to detect absorption-lines weak enough that unseen components should not be saturated. Methods. Interstellar lines of Hii, Ar i, and Fe ii are detected. Column densities are derived directly from the observed line profiles except for H i, whose lines are contaminated by stellar absorption, thus needing the stellar continuum to be removed. We used the TLUSTY models to remove the stellar continuum and isolate the interstellar component. The best fit indicates that the dominant stellar population is B0. The observed far-UV flux agrees with an equivalent number of ∼300 B0 stars. The fit of the interstellar H i line gives a column density of 10 20.3±0.4 cm −2 . Chemical abundances were then computed from the column densities using the dominant ionization stage in the neutral gas. Our abundances are compared to those measured from emission-line spectra in the optical, probing the ionized gas of the H ii regions.Results. Our results suggest that the neutral gas of Pox 36 is metal-deficient by a factor ∼7 as compared to the ionized gas, and they agree with a metallicity of ≈1/35 Z . Elemental depletion is not problematic because of the low dust content along the selected lines of sight. In contrast, the ionized gas shows a clear depletion pattern, with iron being strongly depleted. Conclusions. The abundance discontinuity between the neutral and ionized phases implies that most of the metals released by consecutive star-formation episodes mixes with the H i gas. The volume extent of the enrichment is so large that the metallicity of the neutral gas increases only slightly. The star-forming regions could be enriched only by a small fraction (∼1%), but it would greatly enhance its metallicity. Our results are compared to those of other BCDs. We confirm the overall underabundance of metals in their neutral gas, with perhaps only the lowest metallicity BCDs showing no discontinuity.

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Section: Introductionmentioning

confidence: 99%

Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

Lebouteiller¹,

Kunth

Thuan

et al. 2008

A&A

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“…Mean infall velocity of clouds (thick line, left scale) from an HI reservoir in a 10 9 MG) dIrr chemodynamical model (Rieschick & Hensler 2003) and the corresponding fall-back time of metals (grey line, right scale) produced by a former generation of massive stars. The metals are expelled from the dIrr by a galactic wind, condensed on the infalling clouds, and returning smoothly incorporated into the clouds.…”

Section: Resultsmentioning

confidence: 99%

“…Because of the local coexistence of both gas phases and due to the turbulence and fragmentation in superbubble shells the freshly released SNII elements are mixed into the cool gas. We have traced the path of SNII elements in a 10 9 M 8 chemo-dynamical dlrr model (described in Rieschick & Hensler 2003) and analysed with respect to the local gas mixing and metal transport from the hot into the cool gas phase. The results in Fig.4 show that almost 25% of the metals produced in massive stars are deposited close to the SF sites themselves and, by this, lead to a local self-enrichment within 1 kpc on typical timescales in the range of 10 Myrs.…”

Section: Gas Mixing Between Infall and Outflowmentioning

confidence: 99%

Gas Mixing, Gas Cycles and the Chemical Evolution of Dwarf Irregular Galaxies

Hensler

Köppen

Pflamm

et al. 2004

Symp. - Int. Astron. Union

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Abstract. Dwarf galaxies are ideal laboratories to study influential effects on galaxy evolution. In particular, their gas-rich variant with very active star formation, starbursting dwarf irregulars, shows chemical and structural signatures that lead unambiguously to the conclusion that they are standing in a vital contact with their surroundings. Gas infall cannot only trigger star formation but also allows for a reduction of the metal content. On the other hand, active star formation ignites numerous supernovae type II which accumulate and can produce a galactic wind. This again depletes the metals pushing them into a gas mixing cycle with different timescales, locally of about 10 Myrs, but an galactic scales of at least 1 Gyr. This paper illuminates the different processes like gas infall and outflow and their effects on the chemical evolution, the star formation, and the gas mixing in dwarf irregular galaxies.

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“…The basic parameter switching between both processes, σ 0 , is set to 0.03 according to Cowie et al (1981). As a CE test for our code, we calculate the evolution of a "hypothetical" gas system inside a dark matter (DM) halo and compare the results with a 2d multi-phase hydro mesh-code (Rieschick & Hensler, 2000) for the same system. The initial total gas mass amounts to 2 × 10 9 M ⊙ (99% "COLD" + 1% "HOT") and is distributed according to a Plummer-Kuzmin disk with parameters a=0.1 kpc and b=2 kpc (Miyamoto & Nagai, 1975).…”

Section: The Multi-phase Processesmentioning

confidence: 99%

A Multi-Phase Chemo-Dynamical SPH Code for Galaxy Evolution. Testing the Code

Berczik

Hensler

Theis

et al. 2003

The Evolution of Galaxies

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Abstract. In this paper we present some test results of our newly developed Multi-Phase Chemo-Dynamical Smoothed Particle Hydrodynamics (MP-CD-SPH) code for galaxy evolution. At first, we present a test of the "pure" hydro SPH part of the code. Then we describe and test the multi-phase description of the gaseous components of the interstellar matter. In this second part we also compare our condensation and evaporation description with the results of a previous 2d multi-phase hydrodynamic mesh code.

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Cited by 7 publications

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Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

Gas Mixing, Gas Cycles and the Chemical Evolution of Dwarf Irregular Galaxies

A Multi-Phase Chemo-Dynamical SPH Code for Galaxy Evolution. Testing the Code

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