Found 34 talks width keyword star formation

Tuesday February 28, 2012
Dr. Almudena Alonso Herrero
Instituto de Astrofísica de Cantabria, Spain


Luminous Infrared Galaxies (LIR=10^11-10^12Lsun) have star formation rates in the range of ~20-200Msun/yr. In the local Universe ~50% LIRGs show AGN or AGN/SB composite nuclear activity from optical spectroscopy. We decompose Spitzer/IRS 5-35micron spectra of a complete sample of 50 local (d<75Mpc) LIRGs using SB and AGN clumpy torus model templates. We derive a mid-IR AGN detection rate in our sample of local LIRGs of 50%. We also compare the continuum mid-IR AGN detection with other indicators in the mid-IR, optical and X-rays. We estimate for the first time the AGN bolometric contribution to the IR luminosity of the galaxies in local LIRGs. We find that one-third of local LIRGs have LAGN(bol)/LIR>0.05, with only ~10% having a significant contribution LAGN(bol)/LIR>0.25. This is in line with results of Nardini et al. (2010) that only at LIR>3x10^12Lsun the AGN starts dominating bolometrically the IR luminosity in the majority of the systems.

Thursday January 26, 2012
Mr. Thomas de Boer
Kapteyn Astronomical Institute Groningen, The Netherlands


We present the detailed Star Formation History of the nearby Sculptor and Fornax dwarf spheroidal galaxies, from wide-field photometry of resolved stars, going down to the oldest Main Sequence Turn-Off. The accurately flux calibrated, wide-field Colour-Magnitude Diagrams are used directly in combination with spectroscopic metallicities of individual RGB stars to constrain the ages of different stellar populations, and derive the Star Formation History with particular accuracy.
The detailed Star Formation History shows the star formation at different ages and metallicities, at different positions in the galaxy, and shows that the known metallicity gradients are well matched to an age gradient. The obtained SFH is used to determine accurate age estimates for individual RGB stars, for which spectroscopic abundances (alpha-elements, r- and s-process elements) are known. In this way, we obtain the accurate age-metallicity relation of each galaxy, as well as the temporal evolution of alpha-element abundances.
This allows us to study, for the first time, the timescale of chemical evolution in these two dwarf galaxies, and determine an accurate age of the "knee" in the alpha-element distribution. Finally, we compare the timescale of chemical evolution in both dwarf galaxies, and determine whether the chemical abundance patterns seen in galaxies with recent episodes of star formation are a direct continuation of those with only old populations.

Thursday November 24, 2011
Dr. Maritza A. Lara-Lopez
Australian Astronomical Observatory, Australia


To understand the formation and evolution of galaxies, it is important to have a full comprehension of the role played by Metallicity, Star Formation Rate (SFR), and stellar mass of galaxies. The interplay of these parameters at different redshifts will substantially affect the evolution of galaxies and, as a consequence, the evolution of these parameters provides important constraints for the galaxy evolution models. We studied the relationships and dependencies between the SFR, stellar mass, and gas metallicity of star forming galaxies from the Sloan Digital Sky Survey-Data Release 7 (SDSS DR7) and Galaxy and Mass Assembly (GAMA) surveys. We have combined both surveys finding evidence of SFR and metallicity evolution for galaxies down to redshift ~0.2. Also, we have proved the existence of a Fundamental Plane in the 3D space formed by the SFR, mass and metallicity for the SDSS and GAMA samples.

Tuesday August 2, 2011
Dr. Carlos González Fernández
University of Alicante, Spain


With the discovery of several massive, young clusters in the last five years, the area around the base of the Scutum-Crux arm (around l=28) has become one of the more intense stellar formation areas in the whole Galaxy. This is not totally unexpected, as it is just there where it was predicted that the long bar of the Milky Way would come into contact with the disk, triggering stellar formation. With this talk we review all these evidences and we bring others into light, as we try to obtain a clearer picture of what is happening in these areas and what does it tell us about the inner structure of the Galaxy, particularly of the bulge+bar complex.

Thursday July 7, 2011
Prof. Mordecai-Mark Mac Low
Department of Astrophysics, American Museum of Natural History, New York, USA


In this talk I consider two questions. First, I investigate the formation of molecular clouds from diffuse interstellar gas. It has been argued that the midplane pressure controls the fraction of molecular hydrogen present, and thus the star formation rate. Alternatively, I and others have suggested that the gravitational instability of the disk controls both. I present numerical results demonstrating that the observed correlations between midplane pressure, molecular hydrogen fraction, and star formation rate can be explained within the gravitational instability picture. Second, I discuss how ionization affects the formation of massive stars. Although most distinctive observables of massive stars can be traced back to their ionizing radiation, it does not appear to have a strong effect on their actual formation. Rather, I present simulations suggesting that stars only ionize large volumes after their accretion has already been throttled by gravitational fragmentation in the accretion flow. At the same time these models can explain many aspects of the observations of ultracompact H II regions.

Tuesday June 21, 2011
Miss Karla Yulién Peña Ramírez
Instituto de Astrofísica de Canarias


The proper characterization of the least massive population of the young Sigma Orionis star cluster is required to understand the form of the cluster mass function and its impact on our comprehension of the substellar formation processes. SOri70 (T5.5±1) and SOri73, two T-type cluster member candidates, would have likely masses between 3 and 7 MJup if their age is 3 Myr. SOri73 awaits confirmation of its methane atmosphere. Here I present the results of a search of T-type objects in an area of ~120 arcmin^2 in the Sigma Orionis cluster, the confirmation of the presence of methane absorption in SOri73 and the study of SOri70 and 73 cluster membership via photometric colors and accurate proper motion analysis. This results would have a dramatic impact in the cluster mass function, in one of the scenarios explored, they suggest a decrease in cluster members with planetary masses in the interval 3.5-6 Mjup.

Thursday January 27, 2011
Prof. Tom Abel
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, USA


This lecture will address recent progress in modeling the emergence of cosmic structure at high redshifts. Also new insights gained from numerical simulations into the processes relevant for star formation are presented. Rapid magnetic field growth in galaxies and the important role of proto-stellar outflows regulating star formation up to pc scales are particularly highlighted.

Tuesday January 25, 2011
Mr. José Ramón Sánchez Gallego
Instituto de Astrofísica de Canarias, Spain


In this talk I will present the first complete 12CO J=3-2 map of M81, observed as part of the Nearby Galaxies Legacy Survey. We have detected nine regions of significant CO emission located at different positions within the spiral arms, and confirmed that the global CO emission in the galaxy is low. Using a new Hα map obtained with the Isaac Newton Telescope and archival data I will discuss a series of topics including the correlation between the molecular gas and star forming regions, the CO (3-2)/(1-0) line ratio, and the amount of hydrogen produced in photo-dissociation regions near the locations where CO J=3-2 was detected.

Thursday January 13, 2011
Dr. Ben Davies
University of Leeds, UK


Massive stars dominate the light output of entire galaxies, with luminosities in excess of 105 L⊙. This makes them powerful probes with which to study a range of astrophysical phenomena. In this talk I will review the recent results of our group, in which we have been able to shed new light on the recent star-forming history of our Galaxy, and the nature of supernova progenitors. I will also discuss our latest project, which is to use massive stars as tracers of extra-galactic star-forming histories out to distances of 10 Mpc and beyond.

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


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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