Robert Izzard's Pages of Astronomical Happiness


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  Robert Izzard's Talks
Weird, massive thick disc stars
National Astronomy Meeting, Nottingham, UK, June 2016.
Massive stars and massive binary stars
Dublin Institute of Advanced Studies and Armagh Observatory, June 2016.
The origin of the elements
Solarfest, Dunsink Observatory, June 2016.
Massive stars and massive binary stars
Institute of Astronomy, Cambridge, colloquium December 2015.
Introduction to the binary_c code
binary_c days, September 2015.
Single and Binary Stellar Evolution
BRIDGCE annual meeting, September 2015.
Invited Review
Binary systems, their evolution and environment, Ulaan Baatar, September 2014. (Also SOC member.)
Invited Review
Why Galaxies Care About AGB Stars III, July 2014.
The origin of the elements and the critical role of binary stars
University of Central Lancashire, Keele University and Warwick University, May 2014.
Invited Speaker
Stellar Tango at the Rockies 2014, Alberta, Canada, March 2014.
The origin of the elements and the critical role of binary stars
TRIUMF, Vancouver, Canada, April 2014.
Rotational mixing in binary stars
VLT-FLAMES meeting, Granada, February 2014.
Chemical Evolution of Binary Stars
invited review at Setting a new standard in the analysis of binary stars, Leuven,, September 2013.
The Physics of the Sun
invited review at Japanese-German Frontiers of Science Symposium, October 2013.
The origin of the elements and the critical role of binary stars
Uppsala and Monash Universities, 2013.
The J-type carbon stars: a solution in sight?
Monash University, 2013.
The origin of the elements
Bonn Astroclub 2013.
The stellar mass function: Binary stellar evolution and the most massive stars
colloquium at Mt. Stromlo Observatory and Uppsala University 2012.
Lithium in the Cosmos: Review
Astrophysics Seminar, AIfA Bonn, 2012.
Massive Binary Stars and self-enrichment of globular clusters
At Reading the book of globular clusters with the lens of stellar evolution, Rome, 2012.
An introduction to and tools for stellar population synthesis
review talk, AIfA Bonn, 2012.
The Henyey Scheme
Technical Astrophysics Seminar, AIfA Bonn, 2012.
The J-type Carbon Stars
Armagh Observatory 2012.
Scientific Writing for Astronomers and Astrophysicists
Invited talk at Armagh Observatory 2012.
Common Envelopes
Invited review at IAU symposium 283 Planetary Nebulae - An Eye to the Future 2011.
The Origin of the Elements
University of Bonn Dies Academicus invited review talk, 2011.
J-type Carbon Stars
AIfA review talk 2011.
The Mysterious Barium Stars
UK National Astronomy meeting 2011.
Mass Transfer In Binary Stars
Colloquium at Lund Observatory, 2010.
Barium Stars Revisited
10th Torino Workshop, Christchuch, NZ 2010; Asymmetric Plantary Nebulae V, Windermere UK 2010.
The Binary/CEMP connection
Colloquium Mt. Stromlo observatory 2010
Binary Stars
Review talk, AIfA Bonn 2009
Common Envelopes
Invited review at IAU symposium 283 Planetary Nebulae - An Eye To The Future
I review recent progress on understanding common-envelope evolution with emphasis on its end result, a (possibly bipolar) planetary nebula. Which stars will go into the common-envelope phase? How is it modelled? What is the outcome and will it lead to a planetary nebula? I review both the detailed modelling approach, e.g.through hydrodynamical simulations, and the population/statistical comparison technique. Future prospects will be considered briefly, e.g. CE/PN research including calibration of models to observations through chemical yield comparisons and improved modelling of progenitors and lifetimes.
The Origin Of The Elements
Inaugural lecture given at the Bonn University Dies Academicus 2011
In just a few thousand years of recorded history, mankind has made great strides in its understanding of the Universe. One of the most fundamental questions we can ask is: what is the origin of the elements that make up every atom in our bodies, of the earth, our sun and all the stars we can see? I will tell the story of the origin of the elements and talk about how much we know and how much remains to be discovered.
J-type carbon stars
Bonn stellar physics group seminar
The J stars are 13C rich carbon stars and are not rare (10% of all C-stars!). How they are they formed? What makes the 13C? What about those with silicate emission? What about their odd chemical abundances? Indeed they remain a mystery...
The Mysterious Barium Stars
Invited talk at the UK National Astronomy Meeting 2011, Llandudno, Wales
The barium stars are G/K giants which contain copious amounts of barium but are not evolved enough to have made it themselves. Instead they acquired their heavy metal from a now dead AGB companion star. Canonical theory of mass transfer and tidal circularization suggests that barium stars with periods less than about twenty years should have circular orbits. That they do not is a serious problem for our understanding of AGB and/or binary-star physics. We investigate by simulating populations of Ba stars and find that our models only match the observed eccentricities and periods if we introduce some exotic new physics, for example a stellar kick at the end of the AGB or interaction with a circumbinary disc.
Mass Transfer in Binary Stars
Colloquium given at Lund Observatory, October 2010
Because most stars are in binaries, if we are to understand stars, and hence star clusters, galaxies and the Universe in general, we must understand binaries. How mass and angular momentum are transferred between stars is critical to our understanding of basic stellar evolution as well as exotica such as type Ia supernovae and gamma-ray bursts.
Barium Stars Revisited
The Asymmetric Planetary Nebulae V conference, Winderemere, UK. With Tyl Dermine and Ross Church.
A kick of a few km s-1 at the end of the AGB gives the barium stars the eccentricity with which they are observed. I discuss the link between these stars, post-AGB stars and planetary nebulae. Offence warning: curry is mentioned.
Barium Stars Revisited
Presented at the 10th Torino Workshop on AGB stars. With Tyl Dermine and Ross Church.
An overview of work so far on white dwarf kicks in barium stars. Adding a moderate kick of a few km s-1 gives the barium stars the required eccentricity but problems with common-envelope evolution and (a lack of) orbital shrinkage remain.
Chemically Peculiar Stars: The Binary/CEMP Connection
Colloquium at Mt. Stromlo Observatory, January 2010
I discuss the two modes of mass transfer in binaries, wind accretion and Roche-lobe overflow. These are applied to populations of chemically peculiar stars with a focus on the carbon-enhanced metal-poor stars and our recent population models of their progenitors.
Review talk on binary stars
Interview for my current position at the AIfA, Bonn
Most stars are in binary systems and they are responsible for many of the most important phenomena in astrophysics. I review some of the processes important to binary-star evolution and show some recent results about CEMP stars.
ULB Binary-star Modelling Effort
Contact group (Belgian astronomy) meeting 2009
In this talk I outline my two-year Marie Curie Intra-European Fellowship project at ULB to create BINSTAR, a full binary-star evolution code for low- and intermediate-mass stellar systems.
Solving the Century-Old R Star Mystery
With Simon Jeffery and John Lattazio
The R stars are peculiar K-type giants which show carbon at their surface. They are also all single stars. The evolution of a single star should not pass through such a phase, so I examine the evidence for a binary merger origin of the R stars. With the aid of population synthesis models various channels for R star formation are examined. The most likely is the merger of a helium white dwarf with a red giant.
Simulating Populations of CEMPs
Presented at "The Origin of the Elements Heavier than Iron" in honour of the 70th birthday of Roberto Gallino
With Evert Glebbeek, Onno Pols and Richard Stancliffe
I present preliminary results of our CEMP population synthesis models. It is already clear that efficient third dredge up is requied down to the very lowest masses, in contradiction of previous stellar evolution models. Nitrogen also seems to present difficulties.
Single and Binary Star Population Synthesis (an overview)
First SINS summer school
The first lecture deals with the theory behind binary population synthesis, introducing necessary concepts such as initial distribution functions and how to count stars. JL didn't like it, but the audience did! The second lecture describes some of the available computer codes and some of my (then) recent results.
Binary AGB Nucleosynthesis
Presented at Asymmetric Planetary Nebulae IV, La Palma, 2007
The effect of duplicity is often ignored when comparing AGB, post-AGB and planetary nebula chemical abundances to stellar evolution models. I show how interaction with a binary companion truncates the TPAGB evolutionary phase and, on average, reduces the production of various elements including carbon and nitrogen.
Reaction rates/NeNa/MgAl
Nuclei in the Cosmos 2006
With Maria Lugaro, Christian Iliadis and Amanda Karakas
We present preliminary results of a project which aims to quantify the uncertainties due to errors in nuclear reaction rates in the production of sodium, neon, magnesium and aluminium in massive AGB stars. In particular, the 22Ne(p,γ)23Na rate is highly uncertain and leads to significant yield variation.
Binary Star Nucleosynthesis
Colloquium talk in Nijmegen, 2006
I present an overview of nucleosynthesis in stars and the effect of duplicity on stellar yields.
Synthetic SAGB models
Torino 8, Granada
With Arend-Jan Poelarends
The chemical yields and properties from super-AGB stars are very uncertain at present. We estimate the number of pulses and chemical yields by incorporation of SAGB star detailed model results into my synthetic AGB code. A major uncertainty is the mass-loss rate which can change the number of thermal pulses by orders of magnitude.
Reaction rates/NeNa/MgAl
Brussels 22nd astronuclear meeting
Preliminary results from the Ne/Na/Mg/Al uncertainty project.
BSE is not just for cows (it's for GCE too)
Presented in many places:
A talk about binary stars, chemical yields, chemical evolution of the early Galaxy and population synthesis.
Initial Distributions of Binary Stars and Chemical Yields
Nucleosynthesis In Binary Stars workshop at the Lorentz Centre, Leiden
A brief talk to demonstrate the dependence of binary stellar yields on initial mass functions and the separation distribution.
Population Nucleosynthesis and rapid He-burning
Halifax
I present an attempt a rapid helium burning in a synthetic AGB model. I never got it to work... but I think I could now!
Binary Carbon Stars
There are many dim carbon stars which, according to standard single-star evolution, should not exist. I estimate the number of these by a population synthesis technique and find an excellent match between the carbon-star luminosity functions I predict for the Magellanic Clouds and the observed distributions.
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