# 2012 Seminars

## 2012 Seminars

 Date Name Institution Title (link to Abstract) 10 February Prof. Michael Shara American Museum of Natural History The Nova – Dwarf Nova Connection 23 February Prof. Norbert Christlieb University of Heidelberg Exploring the early chemical enrichment history of the Galaxy with the most metal-poor stars 2 March Ms. Lizette Guzman-Ramirez University of Manchester Dual Chemistry of GB PNe from HST, VLT and Spitzer’ field of view 8 March Ms. Ashleigh Wachman Macquarie University Cross referencing catalogues of 24 micron compact nebulae in order to group and categorise objects in the Mizuno catalogue 16 March Prof. James M. Jackson Boston University The Millimeter Astronomy Legacy Team 90 GHz Survey (MALT 90) 22 March Prof. Michael Burton University of New South Wales Unveiling the Central Molecular Zone with Mopra 30 March Dr. Pawel Lachowicz Nicolaus Copernicus Astronomical Center, Warsaw Measuring viscosity in accretion discs around black-holes 2 April Dr. Trent Dupuy CfA/SAO Next Generation Tests of Substellar Evolution 13 April Dr. Valentina D’Orazi Macquarie University Abundance variations in globular clusters and the multiple population scenario(s) 17 April Mr.Jean-Claude Passy University of Victoria, Canada and the American Museum of Natural History Modeling Catastrophic Interactions in Binary Stars With Multi-Physics Simulations 20 April Prof. George Jacoby Kitt Peak National Observatory, National Optical Astronomy Observatory The Giant Magellan Telescope: Project Status 27 April Ms. Geraldine Marien Macquarie University Observing small short time-scale variations in spectral lines using fibre Bragg gratings 4 May Dr. Sarah Martell AAO Multiple stellar populations in LMC star clusters 11 May Dr. Andrea Richichi National Astronomical Research Institute of Thailand New binaries in the Pleiades cluster 18 May Dr. Warren Reid Macquarie University A look at hot emission-line stars in the LMC 25 May Dr. Daniela Carollo Macquarie University The Structure and Chemistry of the Halo System of the Milky Way 1 June Prof. Clive Ruggles University of Leicester Ancient Hawaiian Astronomy 15 June Dr. Angel Lopez-Sanchez AAO and Macquarie University Eliminating Error in the Chemical Abundance Scale for Extragalactic H II Regions 20July Prof. Jennifer Patience School of Earth and Space Exploration Companions to A-stars — from stars to planets 3 August Mr. Shane Vickers Macquarie University A Study of post-AGB stars and related objects 3 August Mr. Andrew Lehman Macquarie University Shock Waves in Molecular Clouds 10 August Mr. Carlos Bacigalupo Macquarie University A Compact Spectrograph to Search for Extrasolar Planets 10 August Mr. James Tocknel Macquarie University Polarised emission from the massive black hole at the Galactic centre 31 August Dr. Duane Hamacher Nura Gili, UNSW Aboriginal Astronomy – what is it and what can we learn from it? 7 Sept. Dr. David Frew Macquarie University Are planetary nebulae derived from multiple evolutionary scenarios? 14 Sept. Mr. Nick Cvetojevic Macquarie University Developing the 2nd generation Integrated Photonic Spectrograph 21 Sept. Mr. Arik Mitschang Macquarie University Temporal Variability of Spectral Wind Diagnostics in OB Supergiants 28 Sept. Ms. Tui Britton Macquarie University Methanol Masers in High Mass Star Formation 5 October Dr. Craig O’Neill Macquarie University A window for plate tectonics on rocky planets, and planetary habitability 12 October Miss Izabela Spaleniak Macquarie University Integrated Photonic Lanterns: Multimode to Single Mode Light Converters for Applications in Astronomy 19 October Prof. Brad Schaefer Louisiana State University Recurrent Novae 26 October Miss Elaina Hyde Macquarie University Characterising the Core and Stream of the Sagittarius Dwarf Galaxy 2 November Mr Aaron Rizzuto Macquarie University Characterising the Young Sco-Cen Association. 16 November Miss Magda Guglielmo SIfA – The University of Sydney The genesis of Magellanic Clouds 16 November Mr Prajwal Kafle SIfA – The University of Sydney The Milky Way Halo: Simple, Complex or something else 23 November Miss Christina Blom Swinburne University Investigating galaxy evolution using globular cluster systems

### Miss Christina Blom

Swinburne University

Title: Investigating galaxy evolution using globular cluster systems

Abstract:

The SLUGGS (SAGES Legacy Unifying Globulars and Galaxies Survey) team use globular clusters to probe much further into the outskirts of early type galaxies than is achievable with stellar light. Globular clusters are almost uniformly old and robust to galaxy interactions, allowing us to investigate the assembly history of early type galaxies. My data have unearthed evidence of a very unusual globular cluster subpopulation around a deceptively normal elliptical galaxy. This galaxy, NGC 4365, also shows evidence of tidal interaction with another strange galaxy, NGC 4342. I will talk briefly about what the SLUGG Survey entails and then highlight some of the interesting and puzzling results that I’ve discovered during my PhD.

### Miss Magda Guglielmo

Sydney Institute for Astronomy – The University of Sydney

Title: The genesis of Magellanic Clouds

Abstract:

The debate over the formation of the Magellanic Stream and the past orbits of the Magellanic Clouds around the Galaxy seem to be far from over. Still now, questions as where they come from, if they did fall as a pair or as independent galaxies and how they interact with the Milky Way still remain. Understanding the past history of the Magellanic Clouds allows to better understand the present of these galaxies. In addition, due to the interaction with the Galaxy, the history of these galaxies also contains clues about the past evolution of the Milky Way, giving more constraints about its mass and its potential. With the aim to trace the Magellanic Clouds back in the past, I will present a method which combines a Genetic Algorithm with the N-body Gadget2 code, to perform an automated search of the starting conditions that have led the Clouds into their current positions and velocities.

### Mr Prajwal Kafle

Sydney Institute for Astronomy- The University of Sydney

Title: The Milky Way Halo: Simple, Complex or something else

Abstract:

Is the Milky Way stellar halo a single component, dichotomous or multi-component entity? The topic has recently gathered a lot of attention, and there are claims and counter-claims for each scenario. To investigate the issue, we study the kinematics of Blue Horizontal Branch stars taken from SEGUE/SDSS survey. Our measurements of velocity dispersion and anisotropy profiles of the Milky Way stellar halo reveal the non-smooth, complex nature of the stellar halo. Also, simulated halos formed purely by accretion are found not to reproduce the features seen in the kinematic data. In addition, we also present an unbiased estimate of the mass of the Galaxy and discuss its implications.

### Mr Aaron Rizzuto

Macquarie University

Title: Characterising the Young Sco-Cen Association

Abstract:

Young low-mass stars make ideal targets around which to search for extrasolar planets with imaging techniques such as aperture masking, and these stars are often found in young associations. The closet young (5-20 Myr) association to the sun is the Scorpius-Centaurus OB association. Extrapolation of the association IMF implies that there are thousands of solar-type and later stars to be members of this Scorpius-Centaurus which are as yet undiscovered, making up the vast majority of PMS stars within 200 parsecs. We have begun characterising the low-mass population of the association with Multi-Object Spectroscopy, with targets isolated from background interlopers using a Bayesian selection on proper motions. Along with this we are taking long-baseline optical interferometric observations of newly identified binary systems in Scorpius-Centaurus to determine dynamical masses and more precise ages for the association. These observations will produce an age-calibrated sample of low-mass stars which will form an ideal target list for extrasolar planet search observations using current and next generation AO systems

### Miss Elaina Hyde

Macquarie University

Title: Characterising the Core and Stream of the Sagittarius Dwarf Galaxy

Abstract:

We present the most extensive spectroscopic study of the Sagittarius (Sgr) dwarf galaxy and its associated stream to date. Using over 10,000 AAOmega spectra from the Anglo-Australian Telescope, we derive velocity and abundance information for our target stars, and we use 2MASS infrared photometry to separate out true Sgr members from Galactic foreground contamination. The resulting kinematic and abundance information on Sgr and its stream allow us to learn not only about the evolution of the Sgr dwarf galaxy, but also about some of the properties of the dark matter halo of our own Milky Way galaxy, as demonstrated by a comparison with existing models of the Sgr system.

Louisiana State University

Title: Recurrent Novae

Abstract:

Recurrent novae are normal nova systems (thermonuclear runaways of material accreted onto the surface of a white dwarf) in a Roche lobe filling binary, but the recurrence time scale is on ‘human times’ of a century or less. These are fun and critical systems, with many new results. In particular, I will tell about the two recent eruptions of U Sco and T Pyx. These are fantastically well-observed, with heavy contributions by Australian amateur astronomers, and these two novae now have more observations than all the other novae combined. This has allowed the discovery of two new phenomena; optical flares during the early decline (still mysterious) and optical dipping (likely like X-ray dippers in LMXRBs). There are many tales regarding the discovery and follow-up for these two eruptions. I will also tell about my 24-year-long program of measuring the orbital periods, with this having come to fruition within the last week as part of an ApJLett submission, the mystery of why T Pyx went off, and the discovery of U Sco being the most neon-nova of all.

### Miss Izabela Spaleniak

Macquarie University

Title: Integrated Photonic Lanterns: Multimode to Single Mode Light Converters for Applications in Astronomy

Abstract:

Multimode fibres have been used by astronomers for many years to transport or to reformat light from the telescope focus to instruments placed off telescope. Although, there are definite advantages for single mode fibres, as for example, many photonic devices only function with single mode inputs. All fibre fed spectrographs used in astronomy today use multimode fibre inputs and employ macroscopic optics they are thus bulky, expensive, and not readily scalable. Technologies for miniaturisation using integrated photonics show great promise. The integrated photonic spectrograph requires light input from a single-mode optical fibre. The small core diameters and large mode mismatch of single mode fibres with the seeing limited point-spread function of stellar targets makes it difficult to feed these fibres and hence use them to transport the light directly. A solution to this problem is to use a photonic lantern, which converts a multimode fibre core into a series of single mode fibre cores. The original fabrication method is based on fibres. Here we use the direct laser writing technique to inscribe the photonic lantern waveguides within a glass sample with ultrafast laser pulses. With aim of maximising the throughput we explore the effects of the transition geometry and refractive index contrast on the lantern designs.

### Dr. Craig O’Neill

Macquarie University

Title: A window for plate tectonics on rocky planets, and planetary habitability

Abstract:

Plate tectonics plays a crucial role in the long-term habitability of a planet, in its control over the long-term CO2-silicate weathering cycle, volcanic degassing, and continental production, which has allowed for long-term climate stability on the Earth. It is presumed to be important for exosolar planet surface conditions, but significant debate exists over the probability of plate tectonics elsewhere. The tectonic regime of a planet depends critically on the contributions of basal and internal heating to the planetary mantle, and how these evolve through time. We use mantle convection simulations, with evolving core-mantle boundary temperatures, and radiogenic heat decay, to explore how these factors affect tectonic regime over the lifetime of a planet. The simulations demonstrate i) hot, initial starting conditions can produce a “hot” stagnant-lid regime, whilst simulations starting cool may begin in a plate tectonic regime; ii) Planets may evolve from an initial hot stagnant-lid condition, through an episodic regime lasting 1-3Gyr, into a plate-tectonic regime, and finally into a cold, senescent stagnant lid regime after ~10Gyr of evolution, as heat production and basal temperatures wane; and iii) initial conditions are one of the most sensitive parameters affecting planetary evolution – systems with exactly the same physical parameters may exhibit completely different tectonics depending on initial conditions employed. Estimates of Earth’s initial temperatures suggest Earth may have begun in a hot stagnant lid mode, evolving into an episodic regime throughout most of the Archaean, before finally passing into a plate tectonic regime. The implication of these results is that, for many cases, plate tectonics may be a phase in planetary evolution between hot and cold stagnant states, rather than an end member.

### Tui Britton

Macquarie University

Title: Methanol Masers in High Mass Star Formation

Abstract:

The formation of high mass stars is not well understood even though they are largely responsible for the evolution and structure of galaxies. They evolve rapidly and lie deeply embedded within molecular clouds. However, a useful diagnostic tool for probing these clouds is the naturally occurring astronomical maser; the microwave analogue of a laser. Masers are bright and occur in different molecules, which arise through specific physical and chemical conditions within the clouds. I will discuss how my PhD has evolved and where my research fits into the bigger picture of star formation. I am currently using the methanol maser to identify 60 protostars in the southern sky in order to understand the specific environments of these high mass star forming regions. I will discuss my catalogue and one interesting result that have arisen from my survey of these proto-stars.

### Arik Mitschang

Macquarie University

Title: Temporal Variability of Spectral Wind Diagnostics in OB Supergiants

Abstract:

The He-Like fir triplet line ratios from the X-ray spectra of hot stars have been well established as useful diagnostic tools providing physical insight into their winds. X-ray Variability has been observed in OB-type stars likely originating from binary wind interactions, strong flaring activity or by the line-driven instability mechanism. Typically this variability has been observed in the zeroth order or across broad band regions of the spectrum, line-to-line variations being difficult to observe given the limited number of X-ray photons detectable. Due to their physical origin, the motivations for detecting and characterizing possible variability in the line ratios themselves are quite compelling. The specific origin of such variations is just beginning to be explored in the theoretical stellar wind models, but with little observational support. After over 10 years of flight time, accumulated Chandra observations may now be able to shed light on this topic. Here We explore the fir line ratio variability for several prominent ions in archival Chandra high-resolution X-ray spectra of both primary and serendipitous targets by slicing the spectrum in time, and performing a differential analysis.

### Nick Cvetojevic

Macquarie University

Title: Developing the 2nd generation Integrated Photonic Spectrograph

Abstract:

The Integrated Photonic Spectrograph (IPS) is a complete spectrograph within a single silica photonic chip, that has no moving parts, is highly resistant to stress and temperature induced flexure and is far smaller than existing bulk-optic spectrographs. There has been considerable development in this all-photonic approach, culminating in a recent successful on-telescope test, which saw the world’s first astronomical spectra taken using a photonic spectrograph. However, the device’s performance (in terms of resolving power and wavelength coverage) was limited by the predominantly telecommunications-grade design parameters used in chip manufacturing, and at this stage warrants a substantial redesign of the arrayed waveguide grating structure inside the IPS chips, to optimise it for astronomy. In this talk I will present a comprehensive redesign of arrayed waveguide grating chips to improve specific performance parameters of interest to astronomy. These include the free-spectral range, resolving power and the operational wavelength for the devices, with an analysis of the limitations and benefits of the redesigns for typical astronomical goals. In the talk I will explain how the redesigns, along with other advancements in astrophotonics, can be used in conjunction with adaptive-optics systems to make a prototype instrument that could potentially be used for high-precision radial velocity measurements, and indeed possibly exo-planet detection.

### Dr. David Frew

Macquarie University

Title: Are planetary nebulae derived from multiple evolutionary scenarios?

Abstract:

Our understanding of planetary nebulae (PNe) has been significantly enhanced as a result of several recent large surveys. New discoveries suggest that the ‘PN phenomenon’ is in fact more heterogeneous than previously envisaged. Even after the careful elimination of mimics from Galactic PN catalogues, there remains a surprising diversity in the population of PNe and especially their central stars. Indeed, several evolutionary scenarios are implicated in the formation of objects presently catalogued as PNe. We provide a summary of these evolutionary pathways and give examples of each. Eventually, a full census of local PNe can be used to confront both stellar evolution theory and population synthesis models.

### Dr. Duane Hamacher

Nura Gili, UNSW

Title: Aboriginal Astronomy – what is it and what can we learn from it?

Abstract:

Aboriginal Astronomy” is a discipline of cultural astronomy. This discipline seeks to understand the role, nature, and use of the celestial realm in Aboriginal cultures of Australia. In this talk, I will discuss what the field is, why we research this area, what we can learn from it, and what sorts of results have we found so far. I highlight the successes and failures of the field and discuss ways of moving the discipline into the future.

### James Tocknel

Macquarie University

Title: Polarised emission from the massive black hole at the Galactic centre

Abstract:

At the centre of our galaxy lies the 4×10^6 solar mass black hole Sgr A*. Given that it is the closest supermassive black hole, Sgr A* has been extensively observed across the electromagnetic spectrum in order to understand and test models of accretion onto supermassive black holes. Recent observations suggest that there are polarised flaring events occurring in the accretion flow caused by magnetic reconnection, with the variation in polarisation providing constraints on the physical quantities of the system, such as electron density and source size. My project is focused on the polarised transfer of light through a magnetised medium, using the analytic results of Jones and O’Dell 1977 as a basis for the derivation and solution of the system of ODEs that parameterise the system. These solutions will then be used to compute the time variation of the integrated Stokes parameters, and light curves, for conditions equivalent to those found in Sgr A*

### Carlos Bacigalupo

Macquarie University

Title: A Compact Spectrograph to Search for Extrasolar Planets

Abstract:

The most successful technique so far used to search for extrasolar planets is the radial velocity technique where to and fro motion of a host star caused by its orbiting planet redshifts and blueshifts its light periodically. This has been used on large telescopes with large and expensive instrumentation, only enabling a small amount of observing time per star. We have developed a compact spectrograph fed by one or several single-mode fibres that avoids the need for complex fibre scrambling or gas absorption cells for calibration. In principle, this will enable planet searches around bright stars over the next few years, and paves the way for large networks of small telescopes searching for earth-like planets in the future. We are currently working on characterising this spectrograph to determine its stability, and the fidelity required for a simultaneous calibration source.

### Prof. Jennifer Patience

School of Earth and Space Exploration

Title: Companions to A-stars — from stars to planets

Abstract:

With high angular resolution adaptive optics imaging on 5-8m telescopes, we are conducting two surveys to resolve companions – ranging from stars to planets – around A-stars within 75parsecs. The VAST (Volume-limited A-STar) survey of 374 stars involves snapshot imaging to reveal stellar companions down to the bottom of the Main Sequence for all targets. Combining the AO data with wide field images from all sky surveys, the binary separation distribution for A-stars peaks at a wider value than for the corresponding distribution of lower mass stars. The binary frequency for A-stars is higher than for lower mass stars over the ~30-800 AU separation range. The mass ratio distribution shows a nearly flat distribution for systems separated by <125 AU and a distribution steeply rising to lower mass ratios for wider binaries. The binaries discovered in the VAST survey are used to investigate binary formation scenarios, while the single stars with the youngest ages form a core component for a deeper exoplanet search, the IDPS (International Deep Planet Search) project. To measure the first estimation of the exoplanet frequency at large orbital separations in the 10–300 AU range around A-stars, we have conducted a deep-imaging survey of a sample of 42 stars combining all A-stars observed in previous AO planet search surveys reported in the literature with new AO observations from VLT/NaCo or Gemini/NIRI. The Considering the planet detections and upper limits, we estimate the planet (1–14 MJup) frequency in the range 5–320 AU to be inside 3.7–16.1% at 68% confidence. By comparison, the brown dwarf (15–75 MJup) frequency is similar. The AO data are consistent with a declining number of planets with increasing orbital radius which is distinct from the rising slope inferred from RV surveys around evolved A-stars and suggests that the peak of the planet population around A-stars may occur at separations between the ranges probed by existing RV and current AO observations.

### Andrew Lehmann

Macquarie University

Title: Shock Waves in Molecular Clouds

Abstract:

Giant molecular clouds inhabit the vast space between the stars in our Galaxy. These clouds are quasi-stable against gravitational collapse due to violent internal random motions stirred up by star formation. Previous simulations of these turbulent motions have shown that in the presence of magnetic fields a significant fraction of the turbulent energy dissipates via shock waves. In this project, these shock waves are modelled to determine how the gas is heated, and to follow the chemistry driven by this heating, with the goal of providing observational tests for turbulence models.

### Shane Vickers

Macquarie University

Title: A Study of post-AGB stars and related objects

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. Pre-planetary nebulae are those stars where mass loss has ceased and the outer layers have been ejected but not yet ionized. The calculation of physical characteristics of pre-planetary nebulae are dependent on their distances from Earth, which are not available in the literature for such a large sample size. Distances to $\sim 400$ pre-planetary nebulae/post asymptotic giant branch objects, listed in the Toru\’n catalogue, will be calculated by modelling the spectral energy distributions and numerically integrating to ascertain the total distance-dependent flux of the objects. Pre-planetary nebulae appear to be good `standard candles’, allowing the distances to be calculated by equating the distance dependent flux to the assumed luminosity of $6000~\text{L}_{\odot}$, calculated by the core mass-luminosity relation for post-asymptotic giant branch stars. The calculated Galactic scale heights will be compared with the different morphological populations in the literature and any dependence of morphology on the initial mass of the star will allow a narrowing of the different physical mechanisms responsible for the different shapes. At the end of this project we will have a catalogue of physical properties of these short-lived dying stars that is currently lacking in the literature.

### Dr. Angel Lopez-Sanchez

AAO/Macquarie University

Title: Eliminating Error in the Chemical Abundance Scale for Extragalactic H II Regions

Abstract:

The chemical abundance of the ionized gas is a fundamental parameter to understand galaxy evolution. I will review the most common techniques to derive the chemical abundances (oxygen abundances, O/H) of the ionized gas in extragalactic HII regions and star-forming galaxies. I will discuss both the direct method (when a direct measurement of the electron temperature is known) and the so-called “strong emission line” (SEL) methods (which use bright nebular lines) commonly used to derive the oxygen abundance. I will argue the applicability, biases and limitations of the strong-line methods, as well as the observational effects which should be considered to get reliable measurements. In particular, I will emphasize the importance of determining both the extinction and the ionization degree of the gas to get a good determination of the oxygen abundance, and their application to IFS data. I will also discuss that the O/H measurements derived using photoionization codes (e.g., Kewley & Dopita 2002) are systematically 0.2-0.4 dex higher than those values given by calibrations based on direct estimations of the electron temperature (e.g. Pilyugin et al. 2005, 2010; Pettini & Pagel 2004). In an attempt to remove these systematic errors, I will present my most recent paper (Lopez-Sanchez, Dopita, Kewley, et al. 2012, MNRAS, in press) where we perform a “double-blind experiment” to recover the chemical abundances (using the direct and the most-common SEL methods) of theoretical extragalactic HII regions generated by photoionization models. We also compare the results with those derived using very high-quality data of Galactic and extragalactic HII regions, for which faint oxygen recombination lines are available. We found that only oxygen abundances derived using SEL techniques based on photoionization models agree with those computed by the RL. This result agrees with the hypothesis that small-scale temperature fluctuations exist in HII regions, first proposed by Peimbert (1967).

### Prof. Clive Ruggles

University of Leicester

Title: Ancient Hawaiian Astronomy

Abstract:

For many years, archaeoastronomers around the world have studied the design and orientation of monumental structures such as tombs and temples, trying to understand aspects of prehistoric people understanding of the skies and how these were reflected in their religious beliefs and understanding of the cosmos. Throughout Polynesia, temple enclosures and platforms are ubiquitous, but the practical use of astronomy in navigation is also well known from cultural tradition and oral history. This talk describes how in recent years archaeoastronomy has improved our understanding of sky-related knowledge and practices in Polynesia prior to European contact. It will focus on the Hawaiian Islands, where Clive has been working for over a decade, and particularly on the remote Kahikinui area of the island of Maui, where he has joined forces with Pat Kirch (Berkeley) – a leading expert on Polynesian archaeology, to uncover some intriguing new evidence of astronomical practices related to temple sites in an area populated during the last two or three centuries prior to the arrival of the Europeans.

### Dr. Daniela Carollo

Macquarie University

Title: The Structure and Chemistry of the Halo System of the Milky Way

Abstract:

I summarize the current view of the nature of the halo of the Galaxy, which comprises at least an inner halo and outer halo population, each with distinctly 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 carbon enhanced metal poor stars (CEMP). Such characteristics will be discussed during this talk together with the possible formation scenarios.

### Dr. Warren Reid

Macquarie University

Title: A look at hot emission-line stars in the LMC

Abstract:

The Large Magellanic Cloud (LMC) is a unique laboratory in which to study the peculiar characteristics of massive and luminous emission-line stars. At a known distance of ~50 kpc to all LMC members, modest inclination angle to the line of sight (~21deg) and with relatively low interstellar extinction (Rv = 3.41 ± 0.06), apparent brightness is a good indicator of absolute luminosity to within a few tenths of a magnitude. Taking advantage of these benefits I have identified and began basic analysis of emission-line stars in the LMC. The most prominent observational feature of the emission-line stellar group is the presence of the Ha line. The presence of this emission feature has been widely used as an identifier in the many previous searches for emission-line stars in the LMC. Unfortunately, none of these surveys went particularly deep. The UKST Ha survey of the central 25deg2 of the LMC has changed this situation. Designed to reveal faint emission objects, it has already identified 460 new planetary nebulae within the survey region which were confirmed spectroscopically. I announce the identification of 579 hot emission-line stars with spectral classes B-F out of a total sample of 1,062 emission-line stars of all spectral types uncovered. Only 111 of the B-F sample were previously known or identified while 469 are newly discovered. The majority are Be, B[e], Bpe and HAeBe stars but two are Luminous Blue Variable (LBV) candidates. Our recently submitted paper on the subject (Reid & Parker 2012, MNRAS) provides new, accurate positions, rotational velocities, spectral classifications, emission fluxes and an examination of line profiles. The distribution of radial velocities has been plotted and compared to the heliocentric distributions for PNe and the HI gas disk in the LMC. These finding will be presented in this short talk.

### Dr. Andrea Richichi

National Astronomical Research Institute of Thailand

Title: New binaries in the Pleiades cluster

Abstract:

Using the slightly unconventional technique of lunar occultations, about 30 stars in the Pleiades nearby young open cluster have been investigated at high angular resolution. Seven of them have been found to be binaries with small angular separations, including a few not previously known. I will provide a brief overview of the technique and of an ongoing program of occultation observations from the ESO VLT, and then discuss these recent findings in the context of the binary fraction in the Pleiades and in star-forming regions in general.Time permitting, I should also like to present some news about the Thai astronomical community of which I am now part. I will describe the new 2.4m telescope which saw first light in March 2012. I will also outline a number of research topics in which Thai astronomers are involved and open for possible collaborations.

### Dr. Sarah Martell

Australian Astronomical Observatory

Title: Multiple stellar populations in LMC star clusters

Abstract:

Multiple stellar populations in Galactic globular clusters are a relatively recent, and unexpected, discovery. Globular clusters have been assumed to be simple stellar populations, and the fact that many of them have two or three distinct main sequences or subgiant branches, and that all of them show a characteristic set of variations in light-element abundances (C, N, O, Na), has inspired a great deal of new work aimed at understanding why. I am investigating whether intermediate-age star clusters in the Large Magellanic Cloud, which do show complex photometry, also carry the chemical abundance variations found in Galactic globular clusters. I will describe the observational situation and discuss some of the implications for early star formation, galaxy assembly, and the effects of host galaxy mass on the formation of star clusters.

### Ms. Geraldine Marien

Macquarie University

Title: Observing small short time-scale variations in spectral lines using fibre Bragg gratings

Abstract:There is a large area of the Universe that is still relatively unexplored. Several astronomical events, objects or phenomena exhibit physical processes creating small variations in spectral lines on subminute and subsecond time-scales. Current instrumentation lacks the combination of high spectral and temporal resolution to observe these processes, resulting in an inaccessibility of time dependent information on short-time-scales that is needed to classify these objects on the most fundamental level. Fibre Bragg gratings enable a spectral variation in the stellar target to be converted into a photometric one at the detector, allowing for short timescale variations to be resolved. Fibre Bragg gratings promise this way to surpass current astronomical instrumentation in reaching faster observations with a smaller and simpler instrument.

### Prof. George Jacoby

Kitt Peak National Observatory, National Optical Astronomy Observatory

Title: The Giant Magellan Telescope: Project Status

Abstract:The Giant Magellan Telescope (GMT) is one of three extremely large telescopes currently being designed, in addition to the European ELT and the Thirty Meter Telescope, with Australia as one of the principal partners. GMT’s 25-m diameter is the smallest of the three ELTs, but offers the widest usable field of view and is therefore the most efficient when large samples are needed. I will review the overall project status (technical, financial, partnerships, time lines), and describe the capabilities of the first-generation instruments and their science goals. The telescope and its instruments offers many new opportunities to study details of planetary nebulae that will only be possible with ELTs like GMT, and I will describe a few example projects.

### Mr. Jean-Claude Passy

University of Victoria, Canada and the American Museum of Natural History

Title: Modeling Catastrophic Interactions in Binary Stars With Multi-Physics Simulations

Abstract:Many stars in the Universe are binaries. If both components of the system are close enough they will interact strongly, in particular during the giant phases of the primary. In some cases, a common envelope will start during which the secondary star spirals inside the envelope of the primary, exchanging momentum and energy with the gas. This particular interaction is an essential ingredient for many parts of astrophysics, including the shaping of planetary nebulae, the formation of Type Ia supernovae progenitors and the evolution of planetary systems. In this talk, I will show how we use different numerical techniques to gain a better understanding of the common envelope phase, how well these models compare to observations and what are the implications for the astrophysical phenomena mentioned above.

### Dr. Valentina D’Orazi

Macquarie University

Title: Abundance variations in globular clusters and the multiple population scenario(s)

Abstract:The traditional perspective of globular clusters as simple stellar populations is now overcome. In the last years a lot of observational studies (both spectroscopic and photometric) have revealed the presence of chemical anti-correlations between C,O, Mg and N, Na, and Al, respectively, pointing out to pollution processes and to the existence of multiple stellar generations. In this talk I will review our results from a large observational survey, carried out in the last three years, focused on light and heavy element abundance determination. General implications on cluster formation and early evolution scenarios will be also discussed

### Dr. Trent Dupuy

CfA/SAO

Title: Next Generation Tests of Substellar Evolution

Abstract:TA broad-brush view of the evolution of photometric and spectroscopic Ê properties of brown dwarfs has been in place for nearly a decade, Ê largely thanks to the first parallax programs that allowed modest Ê samples of brown dwarfs to be placed on colour-magnitude diagrams and Ê even smaller samples of dynamical masses barely breaching the Ê hydrogen-fusion boundary. I will present results from our Ê high-precision IR astrometry program at CFHT and laser guide star Ê adaptive optics orbit monitoring at Keck that greatly expand such Ê tests of substellar models. Our more populous sample of ultracool Ê dwarf parallaxes provides new perspectives on the cooling of brown Ê dwarfs: we discover a phase of rapid cloud clearing (the “L/T gap”); Ê quantify the seemingly paradoxical brightening in J-band as objects Ê cool from L to T dwarfs; and identify an unexpectedly large scatter in Ê the absolute magnitudes of cold T dwarfs. With data from Keck we have Ê more than tripled the numbered of dynamical masses for ultracool Ê dwarfs, pushing to much lower temperatures than before. This has Ê enabled the strongest tests of substellar models to date and revealed Ê significant discrepancies with observed colours, temperatures, and even Ê cooling rates, which has implications for cluster IMF determinations Ê and the inferred masses for directly imaged planets.

### Dr. Pawel Lachowicz

Nicolaus Copernicus Astronomical Center, Warsaw

Title: Measuring viscosity in accretion discs around black-holes

Abstract:The accretion process onto black-holes in X-ray binaries is unique in its nature. It led to the discovery of low-frequency quasi-periodic oscillations (QPO) to take place in the accretion discs. Their nature remains mysterious although suggested to be caused by the Lense-Thirring precession. Making use of modern signal processing techniques I will show how adaptive wavelet analysis is able to resolve the time-frequency structure of oscillations believed to appear at different distances from the black-hole in the disc. From the complex statistical picture I will try to present a semi-direct evidence for the turbulence in the hot flow due to magnetohydrodynamical instability (MHD) and the way of deriving the viscous time-scales directly for the first time. If valid, it may lead to drastic changes in the future MHD simulations of accretion flow onto compact objects.

### Prof. Michael Burton

University of New South Wales

Title: Unveiling the Central Molecular Zone with Mopra

Abstract:The Central Molecular Zone (CMZ) contains the richest molecular environment of our Galaxy. Spread over the central ~450×150 parsecs of the Galaxy is found ~50 million solar masses of molecular material. This environment is denser, warmer and more turbulent that that found in the giant molecular clouds of the Galaxy’s spiral arms. Surprisingly, the CMZ is also a rich source of organic molecules, and these are found widely distributed across it, and not just confined to the densest cores as they are in GMCs. Until recently we have lacked the ability to examine closely this organic repository at the centre of our Galaxy. Now, with the 22m Mopra millimetre-wave telescope in Australia, we have undertaken a multiple molecular line survey of the CMZ, mapping simultaneously the distribution and dynamics of 18 molecular lines, emitting from 85-93 GHz, across a 2.5¡x0.5¡ region of the CMZ. This work complements the continuum view from radio, infrared, x-ray and gamma-rays of this exotic and multi-facetted environment. We report on the view that is now emerging of the CMZ, our closest galactic nucleus and the only one we can resolve in detail. This talk is based on the results in a recent paper in MNRAS (Jones et al, 2012, 419, 2961). The extensive data set that accompanies it has also been made publicly available for use in other research projects; see www.phys.unsw.edu.au/mopracmz.

### Prof. James M. Jackson

Boston University

Title: The Millimeter Astronomy Legacy Team 90 GHz Survey (MALT 90)

Abstract:I present results from the first year of the MALT 90 Survey, a multi-line survey of molecular emission from dense, high-mass star-forming cores. MALT90 uses the Mopra 22-m telescope in Australia to map 16 molecular lines simultaneously toward a sample of dense cores identified by the 870 micron ATLASGAL continuum survey. I will describe three early results from the first year’s survey data of 500 cores: (1) a technique to find distances and Galactic structure, (2) the discovery of greatly varying chemical composition and its relation to core evolution, and (3) the extension of the Gao and Solomon relation between molecular line and infrared luminosity, first established for galaxies, to the scale of individual cores.

### Ms. Ashleigh Wachman

Macquarie University

Title: Cross referencing catalogues of 24 micron compact nebulae in order to group and categorise objects in the Mizuno catalogue

Abstract:The Mizuno Catalogue of compact disk and ring sources imaged in 24 microns by the MIPSGAL survey contains many interesting objects and a few potential planetary nebula candidates. This catalogue was cross referenced with databases such as Vizier and Simbad, two catalogues of massive stars and a catalogue of compact bubbles in HII regions. A table of all data available on the data available on each object was created, this table was then divided into subgroups based on radius of nebula in 24 microns, brightness of central star, presence of a visible nebula, and a table of small objects with little additional data. The table of objects with visible (or H-alpha)emissions from their nebulae contains 19 objects of interest that could be potential planetary nebula candidates. From this list five of the most likely are discussed in detail.

### Ms. Lizette Guzman-Ramirez

Jodrell Bank Centre for Astrophysics, University of Manchester

Title: Dual Chemistry of GB PNe from HST, VLT and Spitzer’ field of view

Abstract:Galactic Bulge Planetary Nebulae show evidence of mixed chemistry with emission from both silicate dust and PAHs. We analysed a sample of 40 nebulae using Sptizer, a sub-sample of these were observed with HST and VLT (UVEX and VISIR). A strong correlation is found between strength of the PAH bands and morphology, in particular, the presence of a dense torus. A chemical model is presented which shows that hydrocarbon chains can form within oxygen-rich gas through gas-phase chemical reactions. We conclude that the mixed chemistry phenomenon occurring in the Galactic Bulge Planetary Nebulae is best explained through hydrocarbon chemistry in an UV-irradiated, dense torus.

### Prof. Norbert Christlieb

University of Heidelberg

Title: Exploring the early chemical enrichment history of the Galaxy with the most metal-poor stars

Abstract: Stars preserve in their outer layers the chemical composition of the gas cloud from which they have formed. Since stars lighter than about 0.8 solar masses have lifetimes comparable to the age of the Universe, some relics of the first generations of stars have survived in our Milky Way until today. Stellar spectroscopy, using the largest optical telescopes, hence provides us with an observational channel for studying nucleosynthesis processes in the early Universe. For example, correlations of elemental abundances in large samples of old stars tell us which elements have been produced in the same nucleosynthesis processes, and the abundance patterns of certain classes of stars contain fingerprints of individual nucleosynthesis events, yielding constraints for theoretical nucleosynthesis calculations, as well as on properties of the first generation of stars (e.g., mass, or rotation). In my talk I will discuss selected recent results in this field, and I will present the details of a survey for the most metal-poor stars to be conducted with the Chinese 4m LAMOST telescope.