2014 Abstracts

2014 Abstracts

Dr. Amy Kimball

CSIRO

Title: The Radio Luminosity Function of Optically Selected QSOs: Star Formation and AGNs

Abstract:

Despite decades of study, it has remained unclear whether there are distinct radio-loud and radio-quiet populations of quasi-stellar objects (QSOs). The upgraded Karl G. Jansky Very Large Array has allowed us for the first time to obtain nearly complete radio detections in a volume-limited, optically selected sample of QSOs in the redshift range 0.2 < z < 0.3. We were able to detect sources as faint as log(L_6GHz) ~ 10^21.5 L_sun, well below the radio luminosity that separates star-forming galaxies from radio-loud active galactic nuclei (AGNs) driven by accretion onto a super-massive black hole. Extrapolation of the radio-AGN luminosity function to low luminosities predicts that most QSOs should be extremely radio quiet, but our results show that they are not. The resulting radio luminosity function of QSOs can be explained by the combination of two radio emission components, with AGN emission dominating at the bright end and starbursting host galaxies dominating at the faint end. The hypothesis that faint radio sources in most QSOs are powered by starbursts can be tested with ALMA sub-millimeter observations, to determine whether they follow the radio/far-infrared correlation obeyed by almost all star-forming galaxies, or with high resolution VLBI imaging to look for AGN-jet structure.

Dr. Jan Staff

Macquarie University

Title: Eccentric binary interactions as origin of some optical transient phenomena and nebula formation

Abstract:

Several nebulae may have been formed by binary interactions between an asymptotic giant branch (AGB) star and a smaller companion in eccentric orbits. We have performed a number of 3 dimensional hydrodynamic simulations of binary systems consisting of a 3 solar mass AGB star and a main sequence companion with mass ranging from 1.4 to 2.0 solar masses, in an orbit with eccentricity of 0.7. We started the simulations before the first periastron passage to be subject to Roche lobe overflow so that at the first passage primary mass is transferred to the companion, creating a disk around it. The orbit is altered, and we find that the companion is captured into a common envelope in one or two additional periastron passages. We use these simulations as a basis for an analytical study of the possible jets launched from these simulations, including energies and momenta and compare our results to ranges of observations. Finally we calculate the light emerging from these interactions.

Dr. Donald Goldsmith

Title: DOES THE EARTH GO ROUND THE SUN? PRESENTING ASTRONOMY TO THE PUBLIC

Abstract:

In terms of generating public interest, astronomy reigns as the queen of sciences, provoking interest and attention with news and views from space probes, giant telescopes, and complex instruments that survey the entire cosmos across the entire spectrum of radiation.

How can we best use these waves of attention to engage the public more deeply in learning the fundamental facts that lie behind these news items? Or should that be the chief goal of efforts to deepen public understanding of science? Does it matter whether a person believes that the Earth goes around the sun, or contrariwise? (Sherlock Holmes told Dr. Watson that it does not, but he may have been pulling the doctor’s leg.)

Consider, for example, the fact that we are all now experienced consumers of television broadcasts, yet few among the public wonder how a television works, or can be easily motivated to find out. We scientists believe that a basic knowledge of such facts remains essential if the public is to make anything like informed decisions on matters involving science and technology. But what hope exists for this to occur?

Forty years ago, I left my junior faculty position to become a full-time popularizer of astronomy and science. By writing books and magazine articles, and by working on television documentaries, I have stayed off the streets and had an entirely modest impact on the world, though I like to believe that some of the documentaries have made a difference, such as the original “COSMOS,” with Carl Sagan, and the forthcoming “COSMOS,” with Neil DeGrasse Tyson, to begin broadcast next month in the United States. I’ll try to share my insights about how to touch the public despite its oft-expressed diffidence about scientific matters, and hope to discuss which aspects of the quest for scientific knowledge and understanding most deserve promotion among the public by scientists who are willing to try–despite their own, fully understandable diffidence in these efforts.

Dr. Pablo Galaviz Vilchis

Title: Binary Black Hole mergers in f(R) theory

Abstract:

Alternative gravitational theories are candidates to solve some of the cosmological and astrophysical puzzles like the dark matter and dark energy problems. Particularly, f(R) gravitational theory is a useful toy-model to test some of the modifications of Einstein’s theory. From solar system observations and Eöt-Wash experiments it is possible to set constraints the theory in the weak-field regime. However, the main effect of f(R) theory involves strong gravitational fields. On the other hand, in a near future gravitational wave detectors will bring us a new way to constraint the alternative gravitational theories. Collision of black holes are the most promising sources of gravitational waves. The waveforms generated by collision of black holes can give us a way to confirm or discard the f(R) theory in the strong gravitational regime. In this talk I will review the mathematical background related to f(R) gravity and the numerical technique necessary to model the collision of black holes. I will present numerical results related to the characterisation of the gravitational waves generated by binary black hole collision in the f(R) theory of gravity.

Dr. Ivan Bojicic

Title: The MQ/AAO/Strasbourg Galactic PNe database

Abstract:

We have created a new MQ/AAO/Strasbourg database of all previously known and recently discovered Galactic Planetary Nebulae. We aimed to consolidate and organise scattered observational data, to resolve problems with PN mimics and dubious identifications and to enable easy access and quick sharing of datasets, samples, etc. between researchers. The database provides, where available, access to over 40 types of multi-wavelength images ranging from GALEX in the UV through broad and narrow band optical images to the NIR and MIR and then out to the radio. Spectra, newly updated (and corrected) positions and other pertinent information (including our accurate new line fluxes) for all known Galactic PNe are also provided. In this talk I will present the online interface and capabilities of this new tool for PN research.

Ms. Christina Baldwin

Title: Early-Type Galaxy Stellar Populations in the Near-Infrared

Abstract:

The near-infrared is a diagnostically important but understudied region in galaxies, which is highly sensitive to the poorly understood thermally pulsing asymptotic giant branch phase of stellar evolution. Resolving the contribution of this phase to the NIR will allow the derivation of photometric masses of high-redshift galaxies and the extraction of star formation histories. I have high signal-to-noise NIR data of 13 early-type galaxies, selected from the ATLAS3D sample. The chosen galaxies span a range of ages (1-14Gyr), and all have optical IFU maps; as such I will also make an empirical determination of how NIR diagnostics compare with optical.

Mr. David (Brint) Gardner

Title: Searching for distant galaxy clusters

Abstract:

Star formation in the dense environments of galaxy clusters appears to have shut down around 10 billion year ago. How this happened is not well understood because only a handful of galaxy clusters have been found at this time in the universe.
The aim of my project is to use wide field observations from the newly installed Dark Energy Camera on the 4 metre Blanco telescope to search for galaxy clusters at a distance of at least 10 billion light years. I am expecting to find hundreds of galaxy clusters at this distance which will significantly improve our understanding of galactic evolution.

Ms. Rajika Kuruwita

Title: Fall back disks and the end of the Common Envelope phase

Abstract:

The common envelope interaction is the gateway to all short period, evolved binaries, including the progenitor of type Ia supernovae. Our current efforts to understand common envelope interactions have fallen short in that simulations are unable to produce the small binary separations observed and the envelopes are not unbound. In the current project we investigate a possible scenario for the stage immediately following the common envelope evolution: the fall back of bound gas. We use the Enzo hydrodynamic code to simulate such a fall back. Current progress shows this stage results in a decreased binary separation and the unbinding of some additional gas.

Ms. Tiffany Day

Title: The Flows of Neutral Hydrogen in the Grand Design Spiral Galaxy M83

Abstract:

A key ingredient in understanding galaxy evolution is to determine the presence and structure of extra-planar HI gas within a galaxy. If extra-planar gas is ejected from the plane by supernova explosions, it is to be expected that regions with a high star formation rate, such as spiral arms, show an increased amount of outflow. Even though such a correlation is thought to be seen on a galaxy wide scale in the ionised gas, a detailed understanding is still lacking. Studying the neutral hydrogen gas flows around a single star formation structure, instead of galaxy wide, can provide crucial insight into how gas is ejected from the plane. The spiral arms in the grand design spiral M83 provide an excellent opportunity for studying such flows.

In this project, I will analyse the distribution and kinematics of HI in M83 by producing detailed tilted ring models of the galaxy. Using combined data collected in The HI Nearby Galaxy Survey (THINGS) and The Local Volume HI Survey (LVHIS), a HI cube of unprecedented sensitivity will be used to separate the radial motions of the gas from the vertical motions. This analysis will be focussed on M83’s inner disk and especially its spiral arms. Such an analysis will provide detailed knowledge of the radial and vertical flows in and around the arms of this grand design spiral. These flows contain clues to the origin of gaseous thick disks and can also provide insight into the transport of gas from the outer regions of a galaxy to the inner regions. Additionally I will determine whether the high velocity gas is related to star formation or associated with HI holes, look for anomalies in the velocities of HI, and determine whether the extra-planar gas has the same properties as gaseous thick disks observed in other spiral galaxies (including the Milky Way).

Dr. Jean-Claude Passy

Title: Common envelopes in binary stars: what we know and where to go

Abstract:

The common envelope (CE) interaction is a critical phase of binary evolution that produces numerous classes of astrophysical objects, such as planetary nebulae and supernova Type Ia progenitors. Moreover it can also affect the evolution of planets during the post-main-sequence evolution of their host star. Yet, the CE phase is still poorly understood partially because it has been only seldom witnessed directly. In order to gain a better understanding of this evolutionary phase, one must therefore rely on complementary numerical and analytical techniques. In this talk, I will thus present the results of recent investigations based on hydrodynamics simulations, stellar evolution modelling, and analytical approaches. I will then compare these results to observational evidence and explain how they improve our current understanding of the CE phase, and direct future investigations.

Mr. James Tocknell

Title: Constraints on Common Envelope Magnetic Fields from
Observations of Jets in Planetary Nebulae

Abstract:

The common envelope (CE) interaction describes the swallowing of a nearby companion by a growing, evolving star. CEs that take place during the asymptotic giant branch phase of the primary and may lead to the formation of a planetary nebula (PN) with a post-CE close binary in the middle. We have used published observations of masses and kinematics of jets in four post-CE PN to infer physical characteristics of the CE interaction. In three of the four systems studied, Abell 63, ETHOS 1 and the Necklace PN, the kinematics indicate that the jets were launched a few thousand years before the CE and we favour a scenario where this happened before Roche lobe overflow, although better models of wind accretion and wind Roche lobe overflow are needed. The magnetic fields inferred to launch pre-CE jets are of the order of a few Gauss. In the fourth case, NGC 6778, the kinematics indicate that the jets were launched about 3000 years after the CE interaction. Magnetic fields of the order of a few hundreds to a few thousands Gauss are inferred in this case, approximately in line with predictions of post-CE magnetic fields. However, we remark that in the case of this system, it is impossible to find a reasonable scenario for the formation of the two jet pairs observed: the small orbital separation would preclude the formation of even one accretion disk able to supply the necessary accretion rate to cause the observed jets.

Dr. Julie Banfield

Title: Citizen Science and Radio Galaxy Zoo

Abstract:

Citizen science is a method of conducting scientific research using amateur or nonprofessional scientists. In astronomy, citizen science came to light in 2006 when Kevin Schawinski and Chris Lintott devised a method to use the public to help them visually classify galaxies from the Sloan Digital Sky Survey; calling their project Galaxy Zoo. With the success of Galaxy Zoo, the Zooniverse was created to handle a variety of citizen science projects from space research to humanities research. With the next generation radio telescopes beginning to come online, the large data volumes will require new ways to handle the data. The Evolutionary Map of the Universe, an Australian Square Kilometer Array Pathfinder study, will detect 70 million radio sources in the southern sky. A large number of these sources will be handled by computer algorithms, however, 10% will fail our algorithms. Radio Galaxy Zoo is a project that we have begun to handle these 7 million radio sources. In this talk I will present Radio Galaxy Zoo, the new Zooniverse project and the science we will achieve from this citizen science project.

Prof. Geoffrey C. Clayton

Title: Will R Coronae Borealis Ever Return to Maximum Light?

Abstract:

R Coronae Borealis (R CrB) has been in a deep decline for almost 7 years. Before that, it spent 6 uninterrupted years at maximum light. R CrB is the prototype of its eponymous class of stars, which are very rare, and have many unusual characteristics including extreme hydrogen deficiency, and large, sudden declines in brightness of 8 magnitudes or more. These declines are caused by clouds of carbon dust forming near the atmospheres of the stars, which are later dissipated by radiation pressure. The RCB stars are true irregular variables in that the timing of their declines cannot be predicted, but several RCB stars are also known to begin their declines at a particular phase of their pulsations. There is a wide range of dust formation activity among these stars, as well as as a wide variation in the level of activity for an individual star over time. Long Time Domain observations of the RCB stars are necessary to understand the frequency of their declines, and to give clues about how and when the dust forms around these enigmatic stars.

Dr. Karoline Gilbert

Title: Stellar Halo Formation in a Hierarchical Universe: Lessons from Andromeda

Abstract:

Diffuse, extended stellar populations encode information about the earliest stages of a galaxy’s formation. The growth of the outer stellar halos of large disk galaxies like the Milky Way and Andromeda are thought to be dominated by the hierarchical merging of smaller stellar systems, while the inner halos are thought to be built through a combination of mergers and in situ star formation. Stellar halos thus provide a window into the growth of structure as well as an archaeological record of the population of dwarf galaxies that did not survive until the present day.

Large scale surveys of Andromeda’s resolved stellar populations have revolutionized our view of this galaxy over the past decade. The combination of large-scale, contiguous photometric surveys and pointed spectroscopic surveys has been particularly powerful for discovering and following up new substructures and disentangling the structural components of Andromeda. I will review what we have learned about Andromeda’s stellar halo, dwarf galaxy population, and disk from these surveys, with a focus on recent results from the SPLASH survey, which has now amassed spectra of nearly ten thousand red giant branch stars in Andromeda.

Dr. Daniela Carollo

Title: The Halo System of the Milky Way and the CEMP Stars Connection

Abstract:

Carbon Enhanced Metal Poor stars (CEMPs) have been recognized to be an important stellar component of the halo system of the Milky Way. They contain crucial information on the nature of the nucleosynthesis in the early Galaxy. In this talk I will discuss the general properties of the CEMP stars and their importance in Near Field Cosmology. I will also summarize the current view of the nature of the Galactic stellar halo, which comprises at least an inner- and an outer-halo population, each with different kinematics, spatial distributions, and chemistry, as confirmed both from recent observations and numerical galaxy formation scenarios. These smooth halo components exhibit also a distinct chemical pattern in term of fraction of CEMP stars. Such characteristics will be discussed during this talk together with possible formation scenarios of the the Galaxy and connection with the circumgalactic medium of high redshift galaxies and QSO.

Dr. Nick Cox

Title: Asterospheres: Stellar-wind ISM interaction around young and old stars

Abstract:

When stars plough at supersonic speeds through space the interaction between their stellar winds and the surrounding medium can give rise to spectacular looking asterospheres (c.q. bow shocks or bow (dust) waves). Though the basic physics are the same, the sizes and shapes of these asterospheres can vary drastically for different types of stars or different conditions of the ISM. Even binarity or internal stellar processes can drastically affect the shaping of the observed interaction regions. I will highlight recent Herschel, WISE, and GALEX observations of dust and gas in asterospheres around young hot stars and old cool stars and put those in context of state-of-the-art numerical hydrodynamical simulations. In addition to learn about the physics of bow shocks (cooling/heating, instabilities, etc.) I will also show how these unique astrophysical laboratories can possibly provide us with information on stellar evolution (mass-loss history), binary interaction, dust-gas dynamics, dust processing, and even, local properties of the ISM.

Dr. Birendra Pandey

Title: The stability of a magnetized thin disc

Abstract:

I shall discuss the stability of a thin magnetized disc in which poloidal magnetic field provides the radial support against
gravity of the central star. The mass to flux ratio gradient in such discs plays pivotal role in its stability. If the disc is self- gravitating, the favourable gradient may facilitate the collapse of such disc. Therefore, usual Toomre’s parameter (which provides a useful guide on the stability of a hydrodynamic discs) is not a so useful in magnetized, self-gravitating discs.

Ms. Danica Draskovic

Title: Multi-wavelength Quest for New Planetary Nebulae in the Small Magellanic Cloud and its Outskirts

Abstract:

Planetary Nebulae (PNe) represents one of the final evolutionary stages of low- and intermediate-mass stars, lasting for just 25000 to 50000 years. Most stars from 1 to 8 solar masses will at some point go through the PN phase. However, the brevity of this phase limits the number of PNe visible at any one time, and there are currently ~3500 known in the Galaxy. The story with a local group galaxies is quite similar: ~800 in the Large Magellanic Cloud, ~80 in the Small Magellanic Cloud, and only 4 confirmed PN in the nearby Sagittarius dwarf galaxy, where numbers scale with size and mass. Studies of PNe in the local group galaxies are of huge importance because of the different host environments and metallicities that can shed light on the different galactic evolutionary processes in these systems.

PNe play a crucial role in understanding mass loss for low to intermediate mass stars and the chemical evolution of galaxies due to interstellar medium (ISM) enrichment via PNe ejecta. Their ionized shells exhibit numerous emission lines – excellent laboratories for understanding plasma physics. PNe are visible to great distances due to these strong lines that permit determination of the size, expansion velocity and age. The significance in studying PNe in local-group galaxies is that they are still sufficiently close to be amenable to individual scrutiny. In this project we concentrate on the SMC PNe population that are effectively co-located in a coherent and separate system at known distance. Furthermore, the SMC is sufficiently small in angular size and can be studied in its entirety.

Dr. Richard McDermid

Title: Results from the Atlas3D Survey

Abstract:

The Atlas3D Survey is a multi-wavelength, multi-disciplinary survey of a complete sample of 260 early-type galaxies in the local 40Mpc volume, based on integral field spectroscopy combined with optical imaging, CO and HI radio interferometry, and other ancillary data sets. Here I give an overview of some of the key results coming from the survey over the past three years, including what we can learn from stellar kinematic structures; non-universality of the stellar initial mass function; environmental effects on star formation histories and the neutral and molecular gas; and a new view on galaxy scaling relations. Finally, I will relate some of these findings to recent numerical galaxy formation simulations, which are able to reproduce many of the observables from such IFU surveys, while still adhering to a cosmological context.

Ms. Caterina Tiburzi

Title: Risk of false detections in Pulsar Timing Array experiments

Abstract:

Pulsar Timing Array (PTA) experiments contribute some of the most promising research to current radio pulsar astronomy. The main goal is the direct detection of an isotropic and stochastic gravitational wave background generated by high-redshift and coalescing super massive black hole binaries. This can be achieved by studying trends in the angular correlation of the pulses received from an array of extremely stable pulsars.
However, other phenomena can generate angular correlation as well, such as errors in the used planetary ephemeris and in the clock time standards.
We present the first results from an ongoing study designed to evaluate the signatures left by these effects on the angular correlation of pulsar timing residuals, and elaborate on the risk of false positive detections of the gravitational wave background.

Mr. Dimitri Douchin

Title: Estimating the Binary Fraction of Central Stars of Planetary Nebulae

Abstract:

Are binary stars a preferential channel for the evolution and shaping of planetary nebulae? In this talk, I will present the different efforts I have carried out to estimate the binary central stars of planetary nebula in the frame of my PhD work, as well as the latest results for this number. It will be discussed how these new results challenge the current paradigm of planetary nebula formation and shaping.

Dr. Angel Lopez-Sanchez

Title: Dwarf star-forming galaxies and the assembly of spiral galaxies

Abstract:

In this Colloquium I will review my multi-wavelength analysis of star-forming dwarf galaxies combining deep optical/NIR, UV, and 21-cm HI data and how this study has led me to get conclusions about the mass assembly in nearby spiral galaxies. First I will show some particular results in blue compact dwarf galaxies (BCDGs), such as NGC 5253 or Tol 30, that reinforce the hypothesis that interactions with or between low-luminosity dwarf galaxies or HI clouds are the main trigger mechanism of the star-forming bursts. I will also show some examples of starbursts induced by dwarf galaxies or HI clouds in galaxy groups (HCG 31 and Mkn 1097). Interaction features also are found in apparently isolated BCDGs when observed in HI. Finally, I will present the results of the analysis of the ionized and neutral gas in the interacting galaxy pair NGC 1512/1510. NGC 1510 is a BCDG and NGC 1512 is a spiral galaxy which hosts hundreds of UV-bright stellar clusters in its outskirts. The analysis of many of these knots was possible thanks to the 2dF/AAOmega instrument at the 3.9m AAT. We confirm the detection of ionized gas in the majority of these UV-rich regions and characterize their physical properties, chemical abundances, and kinematics. When combined with the available UV and HI results our new optical data are providing key clues about local star-formation processes in galaxies, the interplay between the ISM and the IGM, the metal redistribution in the outer gaseous discs of spiral galaxies, and the role of interactions with dwarf galaxies in the evolution of the spiral galaxies.

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Mr. Oded Papish

Title: Exploding Core-Collapse Supernovae with Jittering Jets

Abstract:

We present a new model by which narrow jets launched by the newly formed neutron star or black hole at the centre of a core collapse supernova lead to the supernova explosion. We show that under a wide range of parameters the fast narrow jets deposit their energy inside the star via shock waves, and form two hot bubbles that eventually lead to the explosion of the star. The conditions for the jets to explode the star and the physics of the explosion are presented.

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Mr. Andrew Lehmann

Title: Dissipation of Molecular Cloud Turbulence by Magnetohydrodynamic Shockwaves

Abstract:

The origin and character of star formation remains a key open problem in astrophysics. This process is intimately related to the supersonic magnetohydrodynamic (MHD) turbulent dynamics of the giant molecular clouds in which stars form. Simulations have shown that shock waves are responsible for a significant amount of turbulent dissipation. As these shocks dissipate by molecular line cooling of the compressed gas, the nature of the turbulence may be probed by studying the radiative signatures of shocks.

Fast, intermediate and slow MHD shocks differ in how they compress and heat the molecular gas. Fast shocks dissipate most of the turbulent energy when the turbulence is driven, whereas slow shocks dissipate most of the energy when the turbulence is decaying. This means that observational differences between fast and slow shocks also distinguish between driven and decaying turbulence.

Here we use a two-fluid MHD model to compare the characteristics of one-dimensional fast and slow shocks. Fast shocks are magnetically driven, forcing ion species to stream through the neutral gas ahead of the shock front. This magnetic precursor heats the gas sufficiently to create a large transition zone where all the fluid variables only weakly change in the shock front. In contrast, slow shocks are driven by gas pressure where neutral species collide with ion species in a thin hot slab that closely resembles an ordinary gas dynamic shock.

Low-velocity shocks dominate the dissipation of turbulence. For these shocks, we searched for observational diagnostics of the different shock types by following the abundances of a variety of molecules through the shocks and computing the line strengths of carbon monoxide and water. We found that the high-J CO rotational lines differ strongly between fast and slow shocks and therefore are an important probe of turbulence.

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Mr. Roberto Iaconi

Title: Common envelope numerical simulations: What are we missing?

strong>Abstract:

The common envelope (CE) interaction is a very fast astrophysical process (it lasts about a year) whereby a close binary star temporarily becomes one large star. What happens next is anybody’s guess. The two stars may merge, explode or transform into a compact binary. The main way to study this phenomenon are numerical simulations, but nowadays the works that have been made in this direction fail to explain various important questions about the CE.
By carrying out 3-dimensional simulations of the CE interaction using a 3D hydrodynamic plus gravity code, we are trying to push the simulations a step further. We are adding additional ingredients that could be relevant to solve those important questions, in particular we are analysing the effects of the interaction preceding the CE on the CE itself and of the stellar rotation.

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Dr. George Hobbs

Title: Pulsars, gravitational waves, clocks, planets, spacecraft and black holes

Abstract:

I will describe the aims and status of the Parkes Pulsar Timing Array project. I will present recent results that have identified irregularities in terrestrial time standards, determined the mass of the Jovian system, studied the interstellar medium and placed the most stringent constraint to date on the existence of gravitational waves from supermassive binary black hole systems. I will demonstrate that this constraint rules out some models for galaxy evolution. I will discuss our gravitational wave search in context with the recent announcement from the BICEP2 experiment and will discuss future plans for our project.

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Mr. Colin Navin

Title: New members of the galactic globular cluster NGC 1851

Abstract:

NGC1851 is an intriguing Galactic globular cluster (GC) with a bimodal sub-giant branch and a red-giant branch with s-element abundance variations. There are also indications that it is surrounded by a large stellar halo (Olszewski et al, 2009). Medium resolution spectra of 1240 stars were obtained within and outside of the tidal radius of NGC 1851. We calculated heliocentric radial velocities V_R and metallicities [Fe/H] determineed from the near-infrared calcium II triplet (CaT) lines in our spectra. Based on V_R and [Fe/H] we present 14 new members, two of which lie outside the tidal radius of NGC 1851. We also reidentified 119 known members identified in high-resolution spectra (Yong and Grundahl, 2008; Carretta et al, 2010).

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Mr. Carlos Bacigalupo

Title:
Hot Jupiters and Cluster Asteroseismology
Abstract:
The properties of planetary systems, including our own, are intimately connected to the conditions of their natal environments. The metallicity of the host star has a well-known correlation with giant planet frequency. A second key variable in planetary formation is the density of the star formation environment. This variable is largely unprobed because exoplanet surveys have focused on old field dwarfs. I’ll present a method to survey open clusters for hot-Jupiters, to determine if giant planet formation is more or less common in dense environments, combined with the use of asteroseismology to constrain planetary parameters.

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Dr. Joao Bento

Title: The Replicable High-resolution Exoplanets and Asteroseismology (RHEA) spectrograph

Abstract:

The current limitations associated with detecting exoplanets using Radial Velocity (RV) measurements include temperature and pressure stability of spectrographs and efficient fibre scrambling. Additionally, an astrophysical fundamental limitation in the form of noise from stellar activity is becoming increasingly important. This is particularly true for giant stars, where the amplitude of pulsations is comparable to RV signals from hot-Jupiters. Asteroseismological analysis of long-baseline RV measurements is required to measure the intrinsic pulsations of the host star and de-correlate them to search for the planetary signals. Additionally, this analysis provides a useful tool to probe the stellar interiors, and therefore obtain a more accurate and precise estimate of the stellar mass. This is impractical using large telescopes, but possible to do on bright stars with 0.2-0.4m class telescopes, provided they can be fitted with cheap high-resolution spectrographs.

In this talk I will present the current status of development of the Replicable High-Resolution Exoplanets and Asteroseismology (RHEA) spectrograph, an inexpensive compact single-mode fibre-fed spectrograph being developed at Macquarie University with the aim of serving as the basis of a series of spectrographs to be deployed on small telescopes for exoplanet and asteroseismological studies.

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Dr. Trevor Mendel

Title: Mergers, Interactions, and evolution of galaxies over the past 9 billion years

Abstract: In this talk I’ll give an overview of work aimed at understanding evolution of the galaxy population both locally and at high redshift.  I’ll discuss the role of galaxy-galaxy interactions in the local universe in triggering star formation, active galactic nuclei, and, ultimately, morphological transformation.  These studies are possible thanks to the enormous spectroscopic samples available from the SDSS and other local surveys.  I’ll then discuss our recent efforts to extend such evolutionary studies from the peak of cosmic star formation at z ~ 2 to the present using the K-band Multi Object Spectrograph (KMOS) on the VLT.

Mr. Shane Vickers

Title: Improving the distances of Post-AGB stars and their kin.

Abstract: Planetary nebulae are the beautiful but short-lived, glowing ejecta of dying low-intermediate mass stars. These objects are formed when an expanding red giant star ejects its outer layers, allowing the hot white dwarf star at the core of the star to shape and ionize the ejected layers of gas. Post-AGB objects (PAGB) include those stars where mass loss has ceased and the outer layers have been ejected but not yet ionized. The calculation of physical characteristics of PAGB are dependent on accurately determined distances, which are scarcely available in the literature. Distances to the known Galactic population of PAGB and similar objects have been determined via modelling their spectral energy distributions (SED). Stellar evolution  models coupled with empirical core-mass distributions suggest that these objects can be assumed to have similar luminosities. The SEDs of the known Galactic PAGB population have been modelled using black bodies however for early-type stars the use of a model atmospheres has also been investigated. With these determined distances we can now begin to probe the physical characteristics of the Galactic PAGB population and their different sub-classes, as well as PAGB populations in the Magellanic Clouds.

MS. Sarah Keith

Title: Non-ideal MHD in protoplanetary accretion zones

Abstract: 

The growth of a giant protoplanet is likely influenced by the presence of a magnetic field. Current models of protoplanetary- and circumplanetary disks rely on magnetically-launched winds or hydromagnetic turbulence to drive inflow. However, whether the disks are able to interact sufficiently with the field for these mechanisms remains a key uncertainty. Non-ideal effects play a significant role in both the field and gas dynamics but studies have only just begun to consider them.

Here we examine the strength and nature of magnetic coupling with the gas flow surrounding a protoplanet by quantifying non-ideal effects to characterise magnetic flux transport. We focus on two distinct regions in the accretion zone: (i) the gap  in the protoplanetary disk evacuated by the protoplanet, and (ii) the circumplanetary accretion disk ringing the protoplanet. We use non-magnetised hydrodynamical simulations and models to examine whether the field is carried along with the accretion flow into the gap and to determine whether the field is strong enough to modify the accretion flow.

We find that the field easily couples to the accretion flow which draws the field into the gap and circumplanetary disk. Strong Hall effect causes conditionally turbulent regions, suggesting the gap gas dynamics are bimodal according to the relative orientation of the rotation and field axes. Strong magnetic forces at the disk surface imply that the field must be accounted for in circumplanetary disk evolution models. We find that the standard uniform accretion across the entire circumplanetary disk accretion requires that the disk is massive and hot. It is unlikely that these extreme conditions met, indicating that the disk experiences outbursting accretion modes, with implications for both planet and satellite formation.

Dr. Megan Johnson

Title: The Three LITTLE Dwarfs: Evolutionary tales uncovered by stars

Abstract: In popular cosmology models, dwarf galaxies are the “building blocks” of giant galaxies and are assumed to be disks. Yet, observationally, even the basic structure of dwarf irregular (dIrr) galaxies remains controversial. Studies of the projected minor-to-major axis ratios in dIrrs provide inconclusive evidence for their three dimensional shape.  Fortunately, the stellar velocity dispersion, together with rotational information, is a diagnostic of how kinematically hot a system is, and, therefore, of its structure. Stellar kinematics were obtained with Kitt Peak National Observatory’s Mayall 4-meter telescope using the Echelle spectrograph as a long-slit optical spectrograph on three dIrrs NGC 1569, DDO 168, and DDO 46.  Gas kinematics for each of these systems were obtained using the Karl G. Jansky Very Large Array by observing the neutral hydrogen 21 cm emission line as part of the LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes; The HI Nearby Galaxy Survey) consortium.  This talk presents the results of these stellar and gas observations and draws conclusions of their shapes, which appear to contradict the minor-to-major axis ratio studies.

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Mr. Glen Rees

Title: Determining the the cosmological sensitivity  of next generation radio continuum surveys

Abstract:  In the last few years it has become readily apparent that the next generation of radio continuum surveys, planned mainly for the SKA and its pathfinders, are capable of placing significant constraints on the parameters of dark energy and modified gravity. Current plans to achieve these results make use of subtle cosmological effects such as the Integrated Sachs-Wolfe Effect, Cosmic Magnification and the spatial power spectrum to constrain a variety of cosmological models. We present recent work comparing the benefits and drawbacks of applying such cosmological tests to the upcoming Evolutionary Map of the Universe (EMU) survey against those to be carried out on optical/IR cosmology surveys, such as the Dark Energy Survey (DES). While both surveys present predictions of their ability to test basic cosmology in a variety of ways, it is currently difficult to compare these predictions due to the lack of a common framework. As such our comparison of the two surveys in a single unified parameter space allows simple, absolute comparisons between them for the first time, thereby enabling us to predict the significance of the EMU cosmology results.

Dr. Kazufumi Torii

Title: High-mass star formation via cloud-cloud collision

Abstract: High-mass stars are very energetic and give significant effects on their surroundings by intense UV radiation and strong stellar wind and ultimately by supernova. Understanding the formation of high-mass stars is therefore one of the most pressing issues in modern astronomy.
Our recent attempts to investigate parental molecular clouds in several high-mass star forming regions have shown that collision between two molecular clouds can trigger formation of high-mass stars  (e.g., Torii et al. 2014, 2011, Fukui et al. 2014, Furukawa et al. 2009). Typical molecular masses of the colliding clouds are 10^3 – 10^5 Msun and the colliding velocity is 10-20 km/s. Strong compression at the interface of the collision provides a large mass accretion rate (>10^-3 Msun) (Inoue & Fukui 2013). This makes it possible to form high-mass stars at very short timescale, ~ 0.1Myr. In this talk, I will summarize a series of our studies working on cloud-cloud collisions and relevant topics.

Dr. Antonino Marasco

Title: Supernova-driven gas accretion in the Milky Way

Abstract: Disc galaxies like the Milky Way need a continuous supply of gas to sustain their star formation. However, there is little observational evidence for accretion of cold gas occurring at the rate required. I present a model of the galactic fountain where cold gas, ejected from the disc into the halo by supernova feedback, triggers the cooling and the subsequent accretion of a significant portion of the inner circumgalactic medium (corona). I apply this model to the Milky Way and I show that a) it reproduces the kinematics and the distribution of both neutral and ionised gas in the halo of our Galaxy; b) it predicts an accretion of coronal gas onto the disc at a rate of a few Mo/yr, enough to sustain the star formation in the disc.

Dr. Jimi Green

Title: The science driving the Square Kilometre Array

Abstract: I will give an overview of the current status of the Square Kilometre Array (SKA) project and the SKA organisation, which now has a dedicated science team tasked with ensuring maximum science productivity from the forthcoming revolutionary telescope. I will give an overview of the SKA facility, the project timeline, the role of the science group and how the community can engage with the project. I will describe the science motivating the design, the ongoing science and design work, and the cutting edge capabilities of the first phase of the SKA, which will provide unique scientific insights.

Mr. Brint Gardner

Title: Searching for distant galaxy clusters

Abstract: Star formation in the dense environments of galaxy clusters appears to have shut down around 10 billion year ago. How this happened is not well understood because only a handful of galaxy clusters have been found at this time in the universe.
I will present two methods for detecting distant galaxy clusters using the galactic red sequence. I applied these two methods to wide field observations from both the newly installed Dark Energy Camera on the 4 metre Blanco telescope and the Spitzer-South Pole Telescope Deep Field survey. I will present my findings from a 25 square degree region in the Southern sky out to a redshift of z = 2.

Ms. Rajika Kuruwita

Title: Fall back disks and the end of the common envelope phase Part 2: What have we found.

Abstract: This talk presents the results of research concerning our understanding of the common envelope phase. The common envelope interaction is the gateway to all short period, evolved binaries, including the progenitor of type Ia supernovae. Our current efforts to understand common envelope interactions have fallen short in that simulations are unable to produce the small binary separations observed and the envelopes are not unbound. During my masters project we investigated a possible scenario for the stage immediately following the common envelope evolution: the fall back of bound gas. We use the Enzo hydrodynamic code to simulate a number of fall back events. We found that that fall back of bound gas efficiently reduces the orbital separation of the system. However,  further unbinding of gas is not sufficient and other energy sources are probably required.

Dr. Simon Campbell

Title: Towards 21st century stellar models: Star Clusters, Supercomputing, and Asteroseismology

Abstract: Stellar models are one of the backbones of modern astronomy. Recent advances in observational astronomy – through asteroseismology, precision photometry, high-resolution spectroscopy, and large-scale surveys – are placing stellar models under greater quantitative scrutiny than ever. The model limitations are being exposed and the next generation of stellar models is needed as soon as possible.

Here we review the evolution and importance of core helium burning stars and then discuss a range of methods, both theoretical and observational, that we are using to advance the models.

Known observationally as SdB, red clump, horizontal branch, and second clump stars, core helium burning stars are numerous and relatively luminous and therefore contribute disproportionately to distant/extragalactic emission. Our best models of these stars are very uncertain, and poorly constrained by observations. These uncertainties propagate to the later phases of stellar evolution, undermining the accuracy of models of supernova explosions and red giants – both vital to the chemical evolution of the Universe.

Dr. Warren Reid

Title: A multi-wavelength investigation of newly discovered planetary nebulae in the Large Magellanic Cloud

Abstract: We have recently completed our search for faint PNe in the LMC having included the outer 64 deg2 area not covered in the original UKST survey of the central 25deg2 region. Candidate PNe were selected using the [OIII], [SII] and H-alpha images provided by the Magellanic Cloud Emission Line Survey (MCELS). Four rounds of confirmatory spectroscopic observations using AAOmega on the Anglo-Australian telescope have yielded a further 110 new LMC PNe while confirming the 102 previously known PNe in the outer LMC. These observations, providing medium and high resolution spectra from 3650Ang to 6900Ang have been used to measure fluxes and derive central star temperatures for a series of research projects based on luminosity functions, chemical abundances, central star properties and kinematics.

The resulting [OIII]-based PN luminosity function, apart from providing an excellent standard candle, contains information about the parent population. Our PNLF, which extends down 9 magnitudes, finally allows us to investigate the faint end which holds clues to understanding the insensitivity of the PNLF cut off, whatever the age of the population. With 766 spectroscopically confirmed bright and faint, highly evolved PNe, the shape of the function including the positions of its dips and peak provide new evolutionary insights, revealing evidence of low-mass cores and confirming simulated dynamical time scales.

To better understand the global properties of PNe I will present and compare PNLFs using H-alpha, IRAC (SAGE) and MIPS wavelengths from Spitzer and 2MASS J, H and K bands. We will also take a look at recent multi-wavelength plots comparing Miras to other giant and supergiant stars in the LMC. These stars provide a clue as to the chemical composition of stars that will eventually become PNe. Using the MCELS map I will display the LMC PNe as a function of their position in the LMC. These will then be shown as a function of their radial velocities and compared to the HI disk and other populations, both young and old. I will also show LMC PN positions according to their chemical abundances with particular reference to those PN high in He and N, commonly known as Type I PNe.

Mr. Michael Cowley

Title: A multi-wavelength study of the impact of AGN on their host galaxies

Abstract: An active galactic nucleus, or AGN, refers to the existence of energetic phenomena at the central region of galaxies, which cannot be attributed directly to stellar emission alone. Extensive local surveys in the radio, infrared and X-ray domains have revealed a substantial population of these active galaxies, which are now known to be powered by the accretion processes of supermassive black holes. This raises the question if the enormous amounts of energy liberated by accretion has any impact on host galaxies. In light of this, many galaxy evolution models now incorporate AGN processes and have been successful in reproducing key observables for the co-evolution of AGN and galaxies. However, a reoccurring suggestion that AGNs play a role in the quenching of star formation in blue disk-like galaxies and their transition to red-dead ellipticals, remains a topic of hot debate.

In an effort to help address this, we cross-match our near-infrared ZFOURGE catalogs with radio, x-ray and far-infrared sources to perform a multi-wavelength identification and investigation into the impact of AGNs on their host galaxies out to a redshift of z = 3.2. We compare the host galaxy properties (stellar populations, colours and morphology) of our AGN to those of a mass-similar sample of non-active hosts. In this talk, I will summarise my approach and present preliminary findings of the study.

Ms. Danica Draskovic

Title: Multi-wavelength Quest for New Planetary Nebulae in the Small Magellanic Cloud and its Outskirts

Abstract: Planetary Nebulae (PNe) represents one of the final evolutionary stages of low- and intermediate-mass stars, lasting for just 25000 to 50000 years. Most stars from 1 to 8 solar masses will at some point go through the PN phase. However, the brevity of this phase limits the number of PNe visible at any one time, and there are currently ~3500 known in the Galaxy. The story with a local group galaxies is quite similar: ~800 in the Large Magellanic Cloud, ~80 in the Small Magellanic Cloud, and only 4 confirmed PN in the nearby Sagittarius dwarf galaxy, where numbers scale with size and mass. Studies of PNe in the local group galaxies are of huge importance because of the different host environments and metallicities that can shed light on the different galactic evolutionary processes in these systems.

PNe play a crucial role in understanding mass loss for low to intermediate mass stars and the chemical evolution of galaxies due to interstellar medium (ISM) enrichment via PNe ejecta. Their ionized shells exhibit numerous emission lines – excellent laboratories for understanding plasma physics. PNe are visible to great distances due to these strong lines that permit determination of the size, expansion velocity and age. The significance in studying PNe in local-group galaxies is that they are still sufficiently close to be amenable to individual scrutiny. In this project we concentrate on the SMC PNe population that are effectively co-located in a coherent and separate system at known distance. Furthermore, the SMC is sufficiently small in angular size and can be studied in its entirety.
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More Abstracts to follow soon!

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