Dr. Gayandhi De Silva
Abstract: The GALAH survey is a pioneering survey that is exploring the motions and detailed chemical compositions of 1 million stars in the Milky Way. Closely related to this is the HERMES Open cluster program, collecting uniform high resolution, high signal to noise data for open clusters spanning a large range in age, metallicity and distance. In this presentation I will give an overview of the developments in Galactic Archaeology, the current status and results with a snap shot of science from these surveys.
Dr Valentina Baccetti
Title: Information loss paradox and the effects of black hole radiation.
Abstract: Event horizons are the defining feature of classical black holes. They are the key ingredient of the information loss paradox which, as paradoxes in quantum foundations, is built on a combination of predictions of quantum theory and counterfactual classical features. Within the semi-classical theory we investigate the possibility that black hole radiation still does not allow for a finite time crossing of the Schwarzschild radius of collapsing matter as seen by distant observers. The exact form of the pre-Hawking radiation is not yet settled, and we make only minimal assumptions about its nature
Dr Yang Huang
Title: The LAMOST Galactic Spectroscopic Surveys
Abstract: One of the fundamental tasks of modern astrophysics is to understand how galaxies form and evolve. Generally, the quest can be pursed in two ways: statistical analyses of large samples of distant galaxies (deep-field cosmology) and detailed studies of large samples of member stars in the Local Group of galaxies including our own, the Milky Way (near-field cosmology). Initiated and aimed to make a major contribution to this latter, ‘near-field cosmology’ quest for understanding the galaxy formation and evolution, the LAMOST Galactic Spectroscopic Surveys have hitherto collected quality spectra of over 7M Galactic stars, and this number is still increasing at a rate of 1M per annum. Combining with data from other available photometric, astrometric and spectroscopic surveys (e.g. Gaia, APOGEE, GALAH), the Surveys have yielded a unique dataset to help us draw an exquisite picture of unprecedented detail of our Galaxy, in particular of the Galactic disk. In this talk, I will present the scope and motivation, data reduction and release, as well as scientific results of the surveys.
Dr Simon Murphy
Dr Adriano Poci
We exploit remarkable new spatially-resolved data from the MUSE integral-field unit to conduct a combined dynamics/stellar-populations analysis of the nearby S0 galaxy NGC3115, in order to infer its true formation history. I will present the detailed models that go into this analysis - namely the fully general, triaxial Schwarzschild orbit-based dynamical models, and full-spectral-fitting star-formation histories, as well as how we combine these two concepts to uncover the assembly history of this galaxy.
Dr Christopher Usher
Dr Chris Tout
Title: Highly Magnetic White Dwarfs and other Stars
Abstract: White dwarfs with surface magnetic fields in excess of 1MG are found as isolated single stars and relatively more often in magnetic cataclysmic variables. Some 1,253 white dwarfs with a detached low-mass main-sequence companion are identified in the Sloan Digital Sky Survey but none of these is observed to show evidence for Zeeman splitting of hydrogen lines associated with a magnetic field in excess of 1MG. If such high magnetic fields on white dwarfs result from the isolated evolution of a single star then there should be the same fraction of high field white dwarfs among this SDSS binary sample as among single stars. Thus we deduce that the origin of such high magnetic fields must be intimately tied to the formation of cataclysmic variables. The formation of a CV must involve orbital shrinkage from giant star to main-sequence star dimensions. It is believed that this shrinkage occurs as the low-mass companion and the white dwarf spiral together inside a common envelope. CVs emerge as very close but detached binary stars that are then brought together by magnetic braking or gravitational radiation. We propose that the smaller the orbital separation at the end of the common envelope phase, the stronger the magnetic field and investigate simple dynamo models for which this is a natural outcome.
Title: Exploring the low surface brightness Universe with the Dragonfly Telephoto Array
Abstract: The low surface brightness Universe is largely unexplored. The limiting factors for low surface brightness observations are not photon statistics or image resolution, instead they are systematic factors such as a telescope’ s internal reflections, sky subtraction, flat fielding and the wide-angle point-spread-function. The Dragonfly Telephoto Array addresses these factors by a combination of hardware and software. The telescope consists of 48 commercial Canon telephoto lenses, and is able to see low surface brightness structures about 10 times fainter than previously possible with its 2.4 x 3.2 degree wide field of view. I will describe the technology behind Dragonfly, and how I and my team have used it to discover enormous stellar disks, properties of interstellar dust and ultra-diffuse-galaxies .
Dr Stuart Ryder
Title: Binary companions to stripped-envelope supernovae
Abstract: The classes of Type, Ib, and Ic core-collapse supernovae appear to represent progressively greater stripping of the progenitor star's outer envelope prior to explosion, but it is unclear how much of this stripping is due to stellar winds and mass-loss, or to interaction with a massive binary companion. We have used the Hubble Space Telescope to search for surviving binary companions to nearby stripped-envelope supernovae in the ultraviolet. I will describe our results for the broad-lined Type Ic SN 2002ap, and for the Type IIb SN 2001ig.