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| Date | Speaker | Topic |
|---|
| September 2nd |
Stella Offner
(CfA, Harvard) |
The Role of Episodic Accretion in
Low-Mass Star Formation |
| No abstract available! |
| September 7th |
Rob Izzard
(Bonn) |
The Mischievous J Stars |
| The origin of the elements is a subject that drives much of astrophysics.
Carbon is the element essential to life and so its origin is of particular
importance. Its production in stars leads to the "carbon star" phenomenon:
cool, red-giant carbon stars are formed which are easy to identify even
with low-resolution spectra. There are three main types of red giant C
stars; N type, R type and J type.
* The N type are red giants near the end of their evolution, we think we
understand these (at least qualitatively).
* R types are single stars that have probably undergone some kind of
merger/helium ignition event - we understand these less well but at least
we have some ideas!
* The J type carbon stars are odd because they are rich in the isotope
carbon 13 ... and some have (oxygen-rich!) discs around. We do not
understand this! We have no model! We really had no idea...
... Until now! In this talk I will describe these odd carbon stars and put
forward a binary-star evolutionary model for J stars that we initially
thought was crazy but may just work. |
September 20st
TUESDAY |
Ken McClements
(Culham Laboratory) |
Forced reconnection studies in the MAST
spherical tokamak |
| The merging-compression method of plasma start-up in
the MAST spherical
tokamak experiment provides an opportunity to study magnetic
reconnection in a high temperature plasma with a strong guide magnetic field,
under conditions approximating those of solar corona. Reconnection in
MAST is associated with rapid heating of ions and electrons; the
electron temperature is often observed to have a hollow profile. High
frequency instabilities and filamentary structures are also observed
during and following reconnection, suggesting the presence of fast ions
and turbulence. Preliminary analysis suggests that ion and electron heating may be due to
turbulence, streaming instabilities or Ohmic dissipation, but there are
many unresolved issues. Solar flare acceleration studies are generally focussed on electrons, since these can be detected whereas
sub-MeV ions cannot; however the MAST
results suggest that reconnection leads more naturally to heating and
acceleration of ions than of electrons |
| October 5th |
Prof. Andrew Collier Cameron
(St. Andrews) |
From WASP to Kepler |
| The current tally of confirmed transiting planets now stands at over 150.
Although most of these are hot Jupiters discovered in ground-based wide-field surveys
thousands of candidates from the Kepler mission await confirmation. Their densities
indicate a surprising range of internal structures. The existence of a substantial
population of close-orbiting planets in strongly tilted and even retrograde orbits
suggests that violent multi-body dynamics may play an important role in the formation
of hot Jupiters. |
| October 26th |
Jeffrey Peterson
(Carnegie Mellon) |
21-cm Intensity Mapping |
| By making all-sky observations of 21-cm flux at redshifts near one, the large scale
structure of the Universe can be mapped in three dimensions. This can be accomplished
by studying specific intensity with resolution ~ 10 Mpc, rather than via the usual
galaxy redshift survey. This new technique is called Intensity Mapping. A new type of
radio telescope based on fixed cylinders has been proposed for these observations,
and I will report the progress of the testing of a prototype cylinder telescope built
in Pittsburgh. The primary goal of the program is to detail the expansion history, in
order to constrain dark energy models. To accomplish this the telescope will have
mapping speed about 1000 times faster than any current radio telescope. |
November 1st
TUESDAY |
Prof. Matt Griffin
(Cardiff) |
Herschel and Beyond |
| The far infrared and submillimetre spectral region is
critical to the characterisation of the obscured Universe, both
in our own and nearby galaxies and at high redshift. The Herschel
Space Observatory, which is currently operating, has a passively
cooled 3.5-m diameter telescope and three scientific instruments
which are carrying out sensitive imaging and spectroscopy at
wavelengths between 55 and 671 microns. I will describe the
design and scientific capabilities of Herschel and reviews some
of its early results.
For a comprehensive understanding of the formation of planetary
systems, and the relationship between AGN and their host
galaxies, future space-borne observations will be needed with
improved sensitivity and angular resolution in the far infrared.
The Japanese-led SPace Infrared telescope for Cosmology and
Astrophysics (SPICA) will be the next major far infrared space
astronomy mission. It will carry a 3.2-m telescope cooled
to ~ 6 K by mechanical coolers, and a suite of instruments
covering the 5 - 200 micron range. SPICA's large, cold aperture
will allow a huge increase in sensitivity over current far
infrared facilities. SPICA's far infrared camera and spectrometer,
SAFARI, will cover the wavelength range between 30 and 200
microns with a Fourier Transform Spectrometer (FTS) and sensitive
superconducting bolometer arrays. SAFARI will have an observing
speed orders of magnitude faster than that achieved by Herschel.
I will outline how SPICA's capabilities will bring about a
major advance in our ability to investigate the Universe,
including the spectroscopic study of very distant galaxies
and the characterisation of the dust, ice, and gas from which
new planetary systems form.
|
| November 16th |
Dr. Eduard Kontar
(Glasgow) |
Solar flare energetic particles |
| Our current understanding of the Universe from planetary magnetospheres
to galaxy clusters is heavily due to the existence of the energetic particles and their emission signatures. The solar flares and the solar energetic particles in the heliosphere are unique by its proximity and hence accessibility for detailed studies of the processes governing particle acceleration, transport and escape into the interplanetary space. Understanding of electron propagation and acceleration is also the key element of Sun-Earth connection studies and an important element of Space Weather. Over the last decade or so, the fleet of the Sun-observing satellites and ground-based radio observations have provided us with unprecedented data, bringing invaluable observations but also setting new questions. The new X-ray and radio results are surprising and demonstrate that we are still far from even a agreed scenario for flares. In the talk, I will speak about recent X-ray and radio observations and the challenges in understanding of solar flare energetic particles. |
| November 23rd |
Dr Thorsten Wengler (CERN) |
Schuster Colloquium - LHC results for science bloggers |
| No abstract available! |
| December 7th |
Chris Colins
(LJMU) |
Testing galaxy formation
models using the Most Massive Galaxies |
| The widely accepted model of galaxy assemblage
via hierarchical growth in a Lambda-CDM cosmology, does a pretty good job of reproducing many of the properties of galaxies and
clusters. However, the origin of the brightest galaxies in rich galaxy clusters is still uncertain. Recent observations using
X-ray emitting clusters at z=0.8-1.5 suggest that that these galaxies have not substantially changed in appearance over the last
9 Gyr. This is in stark contrast to the cosmological semi-analytic models of hierarchical evolution, which predict a
significantly slower assemblage history spanning a wider range of cosmological time, indicating that only 20% of the mass of the
brightest galaxies should be in place at z=1. If correct this "extreme downsizing" points towards a current lack of
understanding of either the merging process in the densest regions or the semi-analytic treatment of the baryonic material in
clusters. |
December 9th
FRIDAY |
David Floyd
(Monash Centre for Astrophysics) |
Gravitational Microlensing as a probe of
Quasar Structure |
| I highlight
recent advances in Gravitational Microlensing and Photoionization modelling that are beginning to
resolve the
structure and physics of the central engine in quasars. While quasar accretion disks and broad
line regions will remain well
beyond the resolution limits of our telescopes for the foreseeable future, microlensing provides
us with effective resolutions
~micro-arcseconds, sufficient to study their structure. New photoionization modelling that fully
accounts for the structure of the
hydrogen atom allows individual quasar spectra to place strong constraints on the physical
conditions in their broad line regions.
I present application of these methods to IRTF, Gemini and VLT spectra. |
| December 14th |
Prof David Southwood (Imperial Colleage London) |
Schuster Colloquium - The Cassini-Huygens mission and exploration of Saturn and Titan |
| No abstract available! |
| December 21st |
Jan Cami
(UWO) |
Fullerenes in the circumstellar and interstellar environment |
| The remarkable Spitzer-IRS spectrum of the unusual planetary nebula
Tc1 shows several emission bands that we recently identified with the
infrared active vibrational modes of the neutral fullerene species C60
and C70. These are currently the largest known molecules in space, and
the first large aromatic species that have been identified in
astrophysical environments. The fullerene bands have now been detected
(at estimated abundances of ~0.1--1.5% of the cosmic carbon) in a
variety of sources, consistent with the early suggestion that
fullerenes form in the circumstellar environments of evolved stars,
and survive in the interstellar medium.
In this talk, I will present an overview of the various observations,
and discuss the two most lively debated issues with respect to
astrophysical fullerenes: their formation and their excitation
mechanism. |
| January 25th |
Michael Brown
(Manchester) |
Probing fundamental physics with multi-wavelength cosmology |
| The concordance "Lambda-CDM" cosmological model is a remarkable fit to astronomical observations but also raises profound questions: we do not know how the initial conditions were imprinted in the early Universe, nor do we know the nature of the dark energy. Two emerging fields of observational cosmology which are uniquely suited to investigating these mysteries are the polarisation of the cosmic microwave background (CMB) and weak gravitational lensing. The former is the most powerful way to probe the early Universe while the latter is potentially the most sensitive probe of dark energy. I will summarise my work in both of these fields. In CMB polarisation studies, I will present results from the recent ground-based QUaD experiment and will look forward to what we might see with Planck and future ground-based experiments. In the field of weak lensing, I have recently been considering the prospects for lensing afforded by a new generation of radio instruments. In particular, the polarization information coming from these instruments could play a crucial role in reducing noise and rejecting contamination from the intrinsic alignment of galaxies. I will describe these new ideas, and an e-MERLIN survey being devised to test them, all leading up to definitive radio lensing surveys with the Square Kilometre Array in the next decade. |
| February 1st |
Tom Shanks
(Durham) |
Cosmology and WMAP |
| No abstract available! |
| February 8th |
Ross McLure
(Edinburgh) |
Galaxy evolution at redshifts 6 < z < 9 |
| The search for ultra high-redshift galaxies is motivated by the desire
to constrain the earliest phases of galaxy evolution, and to uncover
the nature of the sources responsible for cosmic reionization. In
recent years this subject has been revolutionised by a combination of
wide-area, multi-wavelength survey campaigns and ultra-deep,
pencil-beam HST imaging. The main body of the talk will summarise
recent work undertaken at the Institute for Astronomy in Edinburgh to
study the luminosity function, stellar masses and star-formation rates
of the 6 < z < 9 galaxy population, using a combination of the
UKIDSS Ultra-Deep Survey and high-resolution HST imaging.
In addition, I will discuss recent spectroscopic results at z>7 and
outline the opportunities offered by a major new near-IR imaging
programme on HST (CANDELS). With a total allocation of 902 orbits,
CANDELS is the largest ever HST programme, and promises to deliver the
first statistical sample of massive galaxies at z>7. |
| February 15th |
Rolf-Dietmar Herzberg
(Liverpool) |
Schuster Colloquium - Alchemy in the 21st century: The quest for super-heavy elements |
| No abstract available! |
| March 7th |
Danielle George
(Manchester) |
LNA Designs for the SKA: A step change for Astronomers and Engineers |
| The strict sensitivity requirements for radio astronomy receivers means that low noise amplifier designers are used to working to strict specifications. Generally, the overriding factor in LNA designs for radio astronomy applications is delivering the lowest noise figure possible with a flat gain across the frequency band of interest. However, the LNA design and development process in the SKA has equal emphasis on low noise, low power consumption and low production cost along with a flat and high gain over a wide frequency band. The large number of LNAs required in the system drives the necessity and importance of these challenging requirements. A number of LNA designs will be presented for the low and mid aperture array systems |
| March 14th |
Chris Parkes
(Manchester) |
Schuster Colloquium - Schuster's dream: Learning from antimatter |
| No abstract available! |
March 16th
Friday |
Paulo Freire
(MPIfR, Bonn) |
The most
constraining test of
alternative theories of gravitation |
| In this talk, I will
present the results of ten years of
timing of the pulsar-white dwarf binary PSR J1738+0333. This is a
millisecond pulsar with a spin period of 5.85 ms and an orbital period
of 8.5 hours. Optical observations of the WD companion measured its
mass and also the mass ratio, thus providing a precise estimate of the
mass of the pulsar and the orbital inclination. For these masses,
general relativity predicts a yearly decrease of the orbital period of
0.87 +/- 0.06 microseconds per year. Precise timing with the Parkes
and Arecibo telescopes allowed a measurement of the intrinsic orbital
decay of the binary, 0.82 +/- 0.10 microseconds per year, which
matches the expectation of general relativity. The difference between
prediction and observation is so small that it introduces the tightest
constraints ever derived from any gravitational experiment on the main
viable classes of alternative theories of gravity. I also discuss the
complementarity of this experiment with the experiments from the
double pulsar and also the Cassini experiment in the Solar System, and
what can be gained from the combination.
|
| March 21st |
Ian McHardy
(Southampton) |
AGN X-ray
Variability and Relationship to Optical and Radio
Variability |
| I will
review the current observations of the X-ray variability of AGN and their relationship to X-ray binary systems. I
will also consider how X-ray variations are related to variations in the optical and radio bands in Seyfert galaxies
and LINERS. |
