scholarly journals About the Chemical Evolution of dSphs (and the peculiar Globular Cluster ω Cen)

2008 ◽  
Vol 4 (S255) ◽  
pp. 152-156 ◽  
Author(s):  
Andrea Marcolini ◽  
Annibale D'Ercole
Keyword(s):  
Chemical Evolution ◽  
Globular Cluster ◽  
Stellar System ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Dwarf Spheroidal Galaxies ◽  
Chemical Enrichment ◽  
Type Ia ◽  
Hydrodynamical Simulations ◽  
Ia Supernovae

AbstractWe present three dimensional hydrodynamical simulations aimed at studying the dynamical and chemical evolution of the interstellar medium (ISM) in isolated dwarf spheroidal galaxies (dSphs). This evolution is driven by the explosion of Type II and Type Ia supernovae, whose different contribution on both the dynamics and chemical enrichment is taken into account. Radiative losses are effective in radiating away the huge amount of energy released by SNe explosions, and the dSph is able to retain most of the gas allowing a long period (≥ 2 − 3 Gyr) of star formation, as usually observed in this kind of galaxies. We are able to reproduce the stellar metallicity distribution function (MDF) as well as the peculiar chemical properties of strongly O-depleted stars observed in several dSphs. The model also naturally predicts two different stellar populations, with an anti-correlation between [Fe/H] and velocity dispersion, similarly to what observed in the Sculptor and Fornax dSphs. These results derive from the inhomogeneous pollution of the SNe Ia, a distinctive characteristic of our model. We also applied the model to the peculiar globular cluster (GC) ω Cen in the hypothesis that it is the remnant of a formerly larger stellar system, possibly a dSph.

scholarly journals Galactic Chemical Evolution in the Context of the Recently Revealed SNe Ia Delay Time Distribution

2011 ◽  
Vol 7 (S281) ◽  
pp. 251-252
Author(s):  
Takuji Tsujimoto
Keyword(s):  
Chemical Evolution ◽  
Delay Time ◽  
Time Distribution ◽  
Chemical Properties ◽  
Thin Disk ◽  
Chemical Enrichment ◽  
Precise Knowledge ◽  
The Galaxy ◽  
Type Ia ◽  
Ia Supernovae

AbstractThe Galaxy is composed of four distinct structures, i.e., halo, bulge, and thick and thin disks, that are formed and evolved on different timescales; thus accordingly the speeds of chemical enrichment are different from one another, which is imprinted in individual stellar abundances. To decipher them, precise knowledge of the timing of the release of nucleosynthesis materials from various production sites is critical. The delay time distribution (DTD) of Type Ia supernovae (SNe Ia), recently revealed by the SNe Ia surveys of external galaxies, is incorporated into the models of chemical evolution for each structure. Here we report that the observed chemical properties for the thin and thick disks are compatible with a new SNe Ia DTD, and suggests a close chemical connection between the two in the way that the thin disk is formed from gas left after thick disk formation. This nicely explains the lack of thin disk stars with [Fe/H] ≲ −0.8. In this new context, a top-heavy IMF for the bulge is firmly confirmed. Finally we discuss the possibility of some modification of the DTD that might be considered for the halo case.

scholarly journals Effects of Supernova Feedback on the Formation of Galaxies

2008 ◽  
Vol 4 (S254) ◽  
pp. 369-374
Author(s):  
Cecilia Scannapieco ◽  
Patricia B. Tissera ◽  
Simon D. M. White ◽  
Volker Springel
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Chemical Properties ◽  
Multiphase Model ◽  
Energy Feedback ◽  
Chemical Enrichment ◽  
Feedback Model ◽  
Type Ia ◽  
Virial Mass ◽  
Hydrodynamical Simulations

AbstractWe study the effects of Supernova (SN) feedback on the formation of galaxies using hydrodynamical simulations in a ΛCDM cosmology. We use an extended version of the code GADGET-2 which includes chemical enrichment and energy feedback by Type II and Type Ia SN, metal-dependent cooling and a multiphase model for the gas component. We focus on the effects of SN feedback on the star formation process, galaxy morphology, evolution of the specific angular momentum and chemical properties. We find that SN feedback plays a fundamental role in galaxy evolution, producing a self-regulated cycle for star formation, preventing the early consumption of gas and allowing disks to form at late times. The SN feedback model is able to reproduce the expected dependence on virial mass, with less massive systems being more strongly affected.

scholarly journals Inhomogeneous chemical enrichment in the Galactic Halo

2015 ◽  
Vol 11 (S317) ◽  
pp. 57-63 ◽  
Author(s):  
Chiaki Kobayashi
Keyword(s):  
Galactic Halo ◽  
Local Variation ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Dwarf Spheroidal Galaxies ◽  
Chemical Enrichment ◽  
Type Ia ◽  
Low Mass ◽  
Long Lifetime ◽  
Ia Supernovae

AbstractIn a galaxy, chemical enrichment takes place in an inhomogeneous fashion, and the Galactic Halo is one of the places where the inhomogeneous effects are imprinted and can be constrained from observations. I show this using my chemodynamical simulations of Milky Way type galaxies. The scatter in the elemental abundances originate from radial migration, merging/accretion of satellite galaxies, local variation of star formation and chemical enrichment, and intrinsic variation of nucleosynthesis yields. In the simulated galaxies, there is no strong age-metallicity relation. This means that the most metal-poor stars are not always the oldest stars, and can be formed in chemically unevolved clouds at later times. The long-lifetime sources of chemical enrichment such as asymptotic giant branch stars or neutron star mergers can contribute at low metallicities. The intrinsic variation of yields are important in the early Universe or metal-poor systems such as in the Galactic halo. The carbon enhancement of extremely metal-poor (EMP) stars can be best explained by faint supernovae, the low [α/Fe] ratios in some EMP stars naturally arise from low-mass (~ 13 - 15M⊙) supernovae, and finally, the [α/Fe] knee in dwarf spheroidal galaxies can be produced by subclasses of Type Ia supernovae such as SN 2002cx-like objects and sub-Chandrasekhar mass explosions.

scholarly journals Star formation in early-type galaxies: the role of stellar winds and kinematics

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Silvia Pellegrini ◽  
Andrea Negri ◽  
Luca Ciotti
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Type Ia Supernovae ◽  
Stellar Winds ◽  
Early Type ◽  
Stellar Component ◽  
Type Ia ◽  
Hydrodynamical Simulations ◽  
Ia Supernovae

AbstractEarly-type galaxies (ETGs) host a hot ISM produced mainly by stellar winds, and heated by Type Ia supernovae and the thermalization of stellar motions. High resolution 2D hydrodynamical simulations showed that ordered rotation in the stellar component results in the formation of a centrifugally supported cold equatorial disc. In a recent numerical investigation we found that subsequent generations of stars are formed in this cold disc; this process consumes most of the cold gas, leaving at the present epoch cold masses comparable to those observed. Most of the new stellar mass formed a few Gyrs ago, and resides in a disc.

scholarly journals Dynamical and Chemical Evolution of IZw18

2004 ◽  
Vol 21 (2) ◽  
pp. 157-160
Author(s):  
Simone Recchi
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Intermediate Mass ◽  
Intermediate Mass Stars ◽  
Formation History ◽  
Type Ia ◽  
Ia Supernovae ◽  
Detailed Chemical

AbstractWe study the effect of different star formation regimes on the dynamical and chemical evolution of IZw18, the most metal-poor dwarf galaxy locally known. To do that we adopt a two-dimensional hydrocode coupled with detailed chemical yields originating from Type II and Type Ia supernovae and from intermediate-mass stars. Particular emphasis is devoted to the problem of mixing of metals. We conclude that, under particular conditions, cooling of metals occurs with a timescale of the order of 10 Myr, thus confirming the hypothesis of instantaneous mixing adopted in chemical evolution models. We try to draw conclusions about the star formation history and the age of the last burst in IZw18.

scholarly journals TURBULENCE IN A THREE-DIMENSIONAL DEFLAGRATION MODEL FOR TYPE Ia SUPERNOVAE. I. SCALING PROPERTIES

2009 ◽  
Vol 696 (2) ◽  
pp. 1491-1497 ◽  
Author(s):  
F. Ciaraldi-Schoolmann ◽  
W. Schmidt ◽  
J. C. Niemeyer ◽  
F. K. Röpke ◽  
W. Hillebrandt
Keyword(s):  
Three Dimensional ◽  
Type Ia Supernovae ◽  
Scaling Properties ◽  
Type Ia ◽  
Ia Supernovae

scholarly journals M31 Globular Cluster Metallicities and Ages

2002 ◽  
Vol 207 ◽  
pp. 58-61
Author(s):  
Pauline Barmby
Keyword(s):  
Chemical Evolution ◽  
Galaxy Formation ◽  
Globular Cluster ◽  
Chemical Enrichment ◽  
Detailed Explanation ◽  
Age Gap ◽  
Small Delay ◽  
Age Of The Universe ◽  
Lower Limits ◽  
The Universe

Globular cluster ages are more than just lower limits to the age of the universe; the distribution of ages constraints the timescales for galaxy formation and chemical evolution. Globular cluster populations with different metallicities have now been detected in many galaxies, and understanding how these populations formed requires knowing their relative ages. We examined the relative ages of the two M31 globular cluster populations using their color and luminosity distributions and found that the metal-rich clusters could be up to 50% younger than the metal-poor clusters. While a small delay in the formation of metal-rich clusters might be imposed by chemical enrichment timescales, a large age gap demands a more detailed explanation. I outline several possibilities and their promises and problems.

scholarly journals Three-dimensional pure deflagration models with nucleosynthesis and synthetic observables for Type Ia supernovae

2013 ◽  
Vol 438 (2) ◽  
pp. 1762-1783 ◽  
Author(s):  
Michael Fink ◽  
Markus Kromer ◽  
Ivo R. Seitenzahl ◽  
Franco Ciaraldi-Schoolmann ◽  
Friedrich K. Röpke ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae
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