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Abundances of N, Si, S, and Fe for 45 damped Lyman alpha systems (DLAs) have been compiled and detailed one-zone chemical evolution models have been constructed for 30 of them. Assuming continuous star formation, we found that final…

We calculate the type Ia supernova rate for different star formation histories in galaxies by adopting the most popular and recent progenitor models. We show that the timescale for the maximum in the type Ia supernova rate, which…

We introduce a metallicity dependence of Type Ia supernova (SN Ia) rate into the Galactic and cosmic chemical evolution models. In our SN Ia progenitor scenario, the accreting white dwarf (WD) blows a strong wind to reach the Chandrasekhar…

Type Ia supernovae (SNe Ia) are thought to be the result of thermonuclear explosions in white dwarfs (WDs). Commonly considered formation pathways include two merging WDs (the double degenerate channel), and a single WD accreting material…

Type-Ia supernovae (SNe Ia) are important distance indicators, element factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution, and endpoints of stellar binary evolution. It has long been clear that a SN Ia must be…

We compute the Type Ia supernova rates in typical elliptical galaxies by varying the progenitor models for Type Ia supernovae. To do that a formalism which takes into account the delay distribution function (DTD) of the explosion times and…

The nature of the progenitors of Type Ia supernovae (SNe Ia) remains a mystery. Comparing theoretical rates and delay-time distributions of SNe Ia with those inferred observationally can constrain their progenitor models. In this work,…

Unusual elemental abundance patterns observed for stars belonging to nearby dwarf spheroidal (dSph) galaxies are discussed. Analysis of the [alpha/H] vs. [Fe/H] diagrams where alpha represents Mg or average of alpha-elements reveals that Fe…

We adopt a new chemical evolution model for the Large Magellanic Cloud (LMC) and thereby investigate its past star formation and chemical enrichment histories. The delay time distribution of type Ia supernovae recently revealed by type Ia…

Type Ia supernovae (SNe Ia) are runaway thermonuclear explosions in white dwarfs that result in the disruption of the white dwarf star, and possibly its nearby stellar companion. SNe Ia occur over an immense range of stellar population age…

The time delay between the formation of a population of stars and the onset of type Ia supernovae (SNe Ia) sets important limits on the masses and nature of SN Ia progenitors. Here we use a new observational technique to measure this time…

We study the nature of Damped Lyman -Alpha systems (DLAs) by means of a comparison between observed abundances and models of chemical evolution of galaxies of different morphological type. In particular, we compare for the first time the…

Type Ia supernovae (SNe Ia) occur in both old, passive galaxies and active, star-forming galaxies. This fact, coupled with the strong dependence of SN Ia rate on star formation rate, suggests that SNe Ia form from stars with a wide range of…

(ABRIDGED) Recently, three important observational results were established: (a) The evolution of the SNIa rate with redshift show that the rate rises up to z~0.8, when the Universe was 6.5 Gyr old, and decreases afterward. (b) The rate of…

Late-time spectra of Type Ia supernovae (SNe Ia) are important in clarifying the physics of their explosions, as they provide key clues to the inner structure of the exploding white dwarfs. We examined late-time optical spectra of 36 SNe…

Supernova rates (hypernova, type II, type Ib/c and type Ia) in a particular galaxy depend on the metallicity (i.e. on the galaxy age), on the physics of star formation and on the binary population. In order to study the time evolution of…

We analyze the evolution of binary stars to calculate synthetic rates and delay times of the most promising Type Ia Supernovae progenitors. We present and discuss evolutionary scenarios in which a white dwarf reaches the Chandrasekhar-mass…

We constrain the role of different SN Ia channels in the chemical enrichment of the Galaxy by studying the abundances of nickel in Galactic stars. We investigate four different SN Ia sub-classes, including the classical single-degenerate…

The identification of the progenitors of Type Ia Supernovae (SNIa) is extremely important in several astrophysical contexts, ranging from stellar evolution in close binary systems to evaluating cosmological parameters. Determining the…

The type Ia supernova (SN Ia) rate, when compared to the cosmic star formation history (SFH), can be used to derive the delay-time distribution (DTD) of SNe Ia, which can distinguish among progenitor models. We present the results of a SN…