Colloquia

Talks given by high profile astronomers and scientists.


eiichiro_komatsu_151112s
Thursday November 12, 2015
Prof. Eiichiro Komatsu
Max Planck Institute for Astrophysics (MPA, Garching, Germany)

Abstract

The Cosmic Microwave Background (CMB), the fossil light of the BigBang, is the oldest light that one can ever hope to observe in ourUniverse. The CMB provides us with a direct image of the Universe whenit was still an "infant" - 380,000 years old - and has enabled us to obtaina wealth of cosmological information, such as the composition, age,geometry, and history of the Universe. Yet, can we go further and learnabout the primordial universe, when it was much younger than 380,000years old, perhaps as young as a tiny fraction of a second? If so, thisgives us a hope to test competing theories about the origin of theUniverse at ultra high energies. In this talk I present the results from theWilkinson Microwave Anisotropy Probe (WMAP) satellite that Icontributed, and then discuss the recent results from the Plancksatellite (in which I am not involved). Finally, I discuss future prospectson ourquest to probe the physical condition of the very early Universe.


Joop_Schaye_151008s
Thursday October 8, 2015
Prof. Joop Schaye
Univ. of Leiden

Abstract

The realism of hydrodynamical simulations of the formation and evolution of galaxies has improved considerably in recent years. I will try to give some insight into the reasons behind this success, focusing in particular on the importance of subgrid models and the associated limitations. I will also present recent results from the cosmological EAGLE simulations as well as from higher-resolution simulations of individual galaxies.


noam_soker_150910s
Thursday September 10, 2015
Prof. Noah Soker
Physics Department TECHNION, Israel

Abstract

I will describe the roles of jets in several quite different astrophysical systems. These include exploding core collapse supernovae, expelling common envelopes, and heating gas in clusters of galaxies. Hot bubbles inflated by jets seem to be a key ingredient in the interaction of jets with the ambient gas. The understanding that jets can efficiently interact with the ambient gas leads to new notions, such as the jittering jets model to explode massive stars, and the grazing envelope evolution(GEE) that can replace the common envelope evolution in some cases.

malcolm_longair_150317s
Tuesday March 17, 2015
Prof. Malcolm Longair
University of Cambridge, UK

Abstract

Divulgation Lecture to Celebrate the International Year of Light and 150th Anniversary of Maxwell´s great paper on Electromagnetism of 1865.


annette_ferguson_150312s
Thursday March 12, 2015
Prof. Annette Ferguson
Royal Astronomical Observatory of Edinburgh, UK

Abstract

Evidence is mounting for the presence of complex low surface brightness structures in the outer regions of galaxies. While the most spectacular examples are provided by systems hosting coherent debris streams, the most common examples may be extremely diffuse stellar envelopes. Wide-field imagers on large telescopes are allowing us to quantitatively explore the resolved stellar populations in these components within and well beyond the Local Group. I will highlight some recent  results from our work and discuss the insight these outer structures provide on understanding massive  galaxy assembly.  I will also discuss how we are using deep HST studies of M31's outer regions to probe its evolutionary history in unprecedented detail.


eline_tolstoy_141030s
Thursday October 30, 2014
Prof. Eline Tolstoy
Kaptein Astronomical Intistute

Abstract

I will talk about how resolved stellar populations in the nearby Local Group dwarf galaxies have been used to study the detailed chemical, kinematic and star formation history of these systems and the link to the properties of the Milky Way. I will mainly discuss the results from the DART spectroscopic surveys of nearby dwarf spheroidal galaxies, determining detailed abundances, looking for CEMP stars and also combining spectroscopy with colour-magnitude diagram analysis to measure the time scale for star formation and chemical evolution.

 




sara_seager_141023s
Thursday October 23, 2014
Prof. Sara Seager
MIT

Abstract

The discovery and characterization of exoplanets have the potential to offer the world one of the most impactful findings ever in the history of astronomy?the identification of life beyond Earth. Life can be inferred by the presence of atmospheric biosignature gases? Gases produced by life that can accumulate to detectable levels in an exoplanet atmosphere. Detection will be made by remote sensing by sophisticated space telescopes. The conviction that biosignature gases will actually be detected in the future is moderated by lessons learned from the dozens of exoplanet atmospheres studied in last decade, namely the difficulty in robustly identifying molecules, the possible interference of clouds, and the permanent limitations from a spectrum of spatially unresolved and globally mixed gases without direct surface observations. The vision for the path to assess the presence of life beyond Earth is being established.


eva_grebel_141009s
Thursday October 9, 2014
Dr. Eva Grebel
Director Astronomisches Rechen-Institut Zentrum für Astronomie der Universität Heidelberg

Abstract

Dwarf galaxies are the most common type of galaxy in the Universe andinclude the most dark-matter-dominated objects known. They offerintriguing insights into evolutionary processes at low halo masses and low metallicities. Moreover, as survivors of a once much more numerous population of building blocks of larger galaxies, they are key to understanding very early star formation processes. The Local Group and particularly the Milky Way's dwarf galaxy entourage offer us the unique possibility to compare in detail dwarf and Galactic populations. This is an important step towards quantifying the magnitude and time scales of dwarf contributions to the build-up of the Milky Way and allows us to test predictions of cosmological theories and hierarchical structure formation.


john_houghton_140327s
Thursday March 27, 2014
Prof. John Houghton
Univ. of Oxford

Abstract

Because of the carbon dioxide emissions from fossil fuel burning, the Earth's atmosphere and oceans are warming through what is known as the "greenhouse effect". Big changes are on their way which we have not yet seen because of the time taken for the oceans to warm. It is essential that human communities prepare to adapt to these changes e.g. in sea level rise, severe heat waves, and a greater frequency of climate extremes.

The challenge to scientists is to learn enough about the complexities of the world's climate system to be able to project the climate's likely future.

The nations and peoples of the world need to recognise the urgency of the many actions that can - and must be taken.


didier_queloz_130627s
Thursday June 27, 2013
Dr. Didier Queloz
Geneva Observatory, Astronomy Department, University of Geneva

Abstract

The discovery of new planets beyond our solar system, in particular the detection and characterization of other habitable planets similar to the Earth, is a fascinating intellectual adventure. The completely unexpected characteristics of exoplanets are capturing the imagination and interest of the scientific community and the general public. More recently the large population of Super-Earth planet questions the universality of our Solar System as a typical planetary system. While the quest to find bodies similar to the Earth is still on going, the first spectra of exoplanets have been taken, signaling the shift from an era of discovery to one of physical and chemical characterization. This talk will provide an overview of current outcomes of planet programs as well as its limitation and prospects to move forward.