Found 5 talks width keyword stellar dynamics

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Wednesday March 26, 2014
Dr. Thorsten Lisker
Astronomisches Rechen-Institut (ARI), Heidelberg

Abstract

Dwarf galaxies are a complex population. They comprise objects with young and old stellar populations, slow and fast rotation, as well as single- and multi-component structure. These characteristics show correlations with environmental density - we thus believe that dwarf galaxies hold a fossil record of how environment affected galaxy evolution. In this talk I will review and discuss recent progress on our understanding of dwarf galaxies in clusters, both from the observational and the modelling side. In particular, I will attempt to reconcile the proposed formation mechanisms of early-type dwarf galaxies - the most abundant population in clusters - with the continuous environmental influence predicted by cosmological simulations.


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Thursday November 4, 2010
Dr. Felix Mirabel
CEA, Service d'Astrophysique, France

Abstract

The so called "dark ages" of the universe began about 400.000 years after the Big Bang as matter cooled down and space became filled with neutral hydrogen for hundreds of millions years. How the Universe was heated and reionized during the first billion years after the Big Bang is a question of topical interest in cosmology. I will show that current theoretical models on the formation and collapse of primordial stars suggest that a large fraction of massive stars should have imploded, forming high-mass black hole X-ray binaries. Then, I will review the recent observations of compact stellar remnants in the near and distant universe that support this theoretical expectation, showing that the thermal (UV and soft X-rays) and non-thermal (hard X-rays, winds and jets) emission from a large population of stellar black holes in high mass binaries heated the intergalactic medium over large volumes of space, complementing the reionization by their stellar progenitors. Feedback from accreting stellar black holes at that epoch would have prevented the formation of the large quantities of low mass dwarf galaxies that are predicted by the cold dark matter model of the universe. A large population of black hole binaries may be important for future observations of gravitational waves as well as for the existing and future atomic hydrogen radio surveys of HI in the early universe.

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Thursday July 22, 2010
Dr. Sebastian F. Sánchez Sánchez
Centro Astronómico Hispano Alemán de Calar Alto, Spain

Abstract

CALIFA is the largest IFS survey ever performed up to date. Recently started, it will observe ~600 galaxies in the Local Universe with PPAK at the 3.5m of the Calar Alto Observatory, sampling most of the size of these galaxies and covering the optical wavelength range between 3700-7100 Å, using to spectroscopic setups. The main goal of this survey is to characterize the spatially resolved spectroscopic properties (both the stellar and ionized gas components) of all the population of galaxies at the current cosmological time, in order to understand in detail the how is the final product of the evolution of galaxies. To do so, the sample will cover all the possible galaxies within the color-magnitude diagram, down to MB ~ -18 mag, from big dry early-types to active fainter late-type galaxies. The main science drivers of the survey is to understand how galaxies evolve within the CM-diagram, understanding the details the process of star formation, metal enrichment, migrations and morphological evolution of galaxies.


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Thursday June 19, 2008
Prof. Ronald Buta
University of Alabama, USA

Abstract

Bars are important engines for the evolution of structure in galaxies. Bars can cause secular evolution of both the gas and stellar distributions in galaxies, and recently it has been suggested that bars may be recurrent features, forming, dissolving, and reforming over a Hubble time. Models also have suggested that the strength of bars depends on how effectively the bar can transfer angular momentum to outer halo material. Evaluating current models requires an effective way of quantifying the strengths of bars. In my presentation, I will describe recent attempts to use gravitational torques implied by near-infrared images as a means of quantifying both bars and spirals in disk galaxies. I will also describe some of the recent findings based on Fourier analysis of early-type galaxy bars.

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Thursday May 29, 2008
Dr. Antonio Sollima
Instituto de Astrofísica de Canarias, Spain

Abstract

I present the first results of a long term project devoted to the study of the evolution of the binary population in globular clusters. Using deep ACS@HST images of a sample of 13 globular clusters I estimated the fraction of binaries in the cores of these clusters. From a theoretical side, I developed a simplified analytical code which simulates the evolution of the properties of the binary population in a dynamically evolving globular cluster. The comparison between theory and observations allows to evaluate the efficiency of the various processes of binary formation and destruction in these stellar systems and their dependence on the main cluster structural and dynamical parameters.


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