Abstracts

Daniel Price: Simulating dust

I will discuss our recent progress in simulating the dynamics of dust in protoplanetary discs, where we hope to go with this and how we can link it all to the star formation process.

Sarah Maddison: The dust content of protoplanetary disks

I will discuss some of the current observational campaigns being conducted to understand the dust content in protoplanetary disks, how they relate to the theory of dust dynamics in disks, and what theory+observations tell us about the planet formation process.

Daniel Bayliss: Probing Exoplanets using Secondary Eclipses

I will outline the work that we have been doing using the FTS, AAT and Gemini telescopes to determine the brightness temperatures and eccentricities for transiting planets and brown dwarfs.

Barnaby Norris: VAMPIRES - Probing the innermost regions of protoplanetary systems with polarimetric aperture-masking

VAMPIRES (Visible Aperture Masking Polarimetric Interferometer for Resolving Exoplanetary Signatures) is a high-angular resolution imager being developed as part of the SCExAO project at the Subaru telescope, in conjunction with the University of Sydney. In contrast to conventional coronographic techniques, aperture masking interferometry has demonstrated the ability to image faint companions at resolutions well beyond the diffraction limit. VAMPIRES leverages this technique in combination with polarimetry, to directly image structure in the inner-most regions of preplanetary systems, at visible wavelengths. VAMPIRES will use starlight scattered by dust in the inner region of such systems to precisely map the disk, gaps, knots and waves that are key to understanding disk evolution and planet formation. With a spatial resolution of ~10 mas but with a maximum field of view of ~500 mas, VAMPIRES perfectly compliments coronographic observations in the near-IR, and in fact can operate simultaneously with IR coronographic observations by utilising the otherwise unused visible wavelengths. High resolutions and dynamic ranges are enabled by VAMPIRES‚ unique triple-layered polarimetric differential calibration system, using simultaneous polarised channel splitting, fast liquid-crystal channel switching and half-wave-plate based channel switching. The first on-sky tests were conducted at the Subaru telescope in July 2013, with further observations planned for early 2014.

Chris Wright: Magnetic fields in the disks around young stars

Magnetic fields are thought to play a significant role in the evolution of young stars, all the way from the collapse phase through to planet formation. Using the unique thermal IR polarimeter CanariCam on the Gran Telescopio Canarias we have obtained sub-arcsecond resolution images of the magnetic field toward a sample of young stars in various phases of evolution. We will present a few select results.

Andrew Prentice: Understanding the chemical makeup of our Solar system in the light of recent changes in measurements of the photospheric and meteoritic abundances of the elements

Since 2003 there has been a major revision in the measurements of the elemental abundances in the photosphere of the Sun and of the elemental abundances recorded in meteorites. Most of the revision has come from a re-evaluation of the! photospheric abundance of C, N and O (Asplund et al, 2009; Lodders et al, 2009; Caffau et al 2010). The main upshot of these changes is that the C/O atom ratio has increased from 0.50 to 0.55 and the O/Si atom ratio from 14 to 17. The meteoritic abundances of the rocky elements and metals have undergone only minor revision. Typically, the Fe/Si atom ratio has increased from 0.838 to 0.87. In this talk I report the outcome of a major upgrade in the computational code for determining the bulk chemical composition of the planetary system and the natural satellite systems of Jupiter and Saturn. This upgrade is based on the new photospheric and meteoritic abundances and on the author’s gas ring model of solar system formation (Prentice 2006 PASA 23 1-11). Several discrepancies which existed previously in matching the bulk iron content of Mercury with the 71% mass per cent inferred from the very high mean density of that planet, namely 5.43 g/cm^3, and the 0.50:0.50 rock-to-water ice mass fractions of Titan, are now resolved by adopting the new solar elemental abundance measurements. Titan is assumed to have condensed in a solar orbit at Saturn’s heliocentric distance, prior to capture by the proto-Saturnian system.

Peter Tuthill: New approaches to Direct Detection

This talk will sketch the diverse work in advanced imaging techniques presently underway at the University of Sydney. Studies of disks and planet-forming environments are underway with present generation 8-m telescopes, as well as planned for JWST and future ELTs.

Jeremy Bailey: Characterisation of Exoplanets using Polarization

Light reflected from the atmospheres of extrasolar planets will be polarized, and the detection and measurement of that polarization provides a means of characterising the atmospheres that provides complementary information to that from spectroscopy. At UNSW we are building a new instrument with the aim of measuring polarization in the combined light of a star and hot Jupiter planet, and thus detecting the polarization of the planet. We have also incorporated polarization capability into our atmospheric modelling code VSTAR. Polarization is particularly sensitive to the presence of atmospheric clouds and hazes. I will describe our current progress on these developments, and discuss the potential of such techniques for the study of exoplanet atmospheres.

Sergiy Shelyag: Simulations of stellar jitter: a pathway to detection of Earth-sized exoplanets?

Convective motions in the outer envelopes of low-mass stars induce variations and radial velocity shifts in spectral line profiles. These variations, known as stellar jitter or astrophysical noise, are of the order of few meters per second. They make it difficult to confirm Earth analogs, which induce Doppler shifts of the order of centimeters per second. Understanding the physical processes involved in generation of astrophysical noise! and its properties could potentially lead to development of the noise removal techniques which are more efficient than current ones. We attempt to develop such technique based on 3d simulation of the solar/stellar photosphere and detailed radiative diagnostics of simulated models. Using parameterisation of granulation patterns, we create full Sun-as-a-star observations, which we then use to generate and study the properties of stellar jitter.

Joao Bento: The Replicable High-resolution Exoplanets and Asteroseismology spectrograph
Radial-velocity (RV) measurements of Main-sequence stars using high-resolution spectrographs are the most successful method for finding exoplanets to date. However, stellar activity is a potential limiting factor towards detections of this kind. Long baseline spectroscopic observations of target stars are required to decorrelate the stellar pulsations and using large diameter telescopes for this purpose is impractical due to time allocation constr! aints. The Replicated High-resolution Exoplanet and Asteroseismology (RHEA) spectrograph is an Echelle fibre-fed single-mode compact spectrograph designed to achieve a resolution of R~50,000 at optical wavelengths. The current design is built with the goal of creating an inexpensive and replicable unit. We aim to use 0.5-2m class telescopes, in which time constraints are much less stringent, and achieve an RV precision of 10-20 m/s for bright stars. We present the design of the prototype, currently being tested on the 16" telescope at the Macquarie University Observatory, and show preliminary results.
Elodie Thilliez: A dynamical test for the terrestrial planets in the habitable zone of HD 204313
Dynamical studies of known multiple planet systems are a vital tool in the search for stable and habitable planet candidates. We present a dynamical study of the three-planet system HD 204313 to determine whether it could harbour an Earth-like planet within its habitable zone for a sufficient time to develop life. We found two semi-stable regions in the system, but neither prove stable for long enough for a terrestrial planet to develop life. This study established a framework for a larger project that will study the dynamical stability of the habitable zone of multiple planet systems, providing a list of interesting targets for future habitable low-mass planet searches.
Rosemary Mardling: Planetary system stability from first principles
Exoplanet surveys such HARPS and Kepler are revealing planetary system architectures that are both robust and delicate in the sense that they are billions of years old, but in some cases would not withstand even mild perturbations. The stability characteristics of these beautiful gravitational molecules may be studied with direct integrations, however, such analysis has little predictive power, it provides no insight into the cause of instability, and the para! meter space grows like 7^N, where N is the number of planets. I will describe the elements of a new formalism which allows one to determine the stability characteristics of small-N systems with arbitrary mass ratios and architectures (including circumbinary systems for example), as well as to study aspects of stable systems such as the interactions responsible for transit timing variations. This will be implemented on the new Geneva DACE system (Data Analysis Center for Exoplanets)
James Gilmore: Habitability and Radiative Properties in Energy Balance Models
Energy balance climate models have regained popularity and are now being used to explore exo-Earth habitability. But how appropriate are these models for exploring habitability? Here I study a one-dimensional diffusive energy balance model (used by, for example, Spiegel et al. ApJ 2008) and analyze the uncertainties of the model snowball transition. To do this, I update the radiative functions using substantially improved measurements from the CERES instruments currently observing Earth's radiative properties. Analysis of the updated functions shows there is a small bias in the energy balance of 3 W/m^2, indicating the approximations in the construction of the radiative properties are reasonable. I also demonstrate a much finer balance exists between Earth's incoming solar and outgoing infrared radiation than previously assumed. This work shows that when using observationally derived radiative functions for an Earth-like planet in this model, the snowball transition can be determined within a semi-major axis of 3%, with a structural uncertainty of 2% in the radiative function construction.
Daniel Cotton: Modelling of the Earth's Atmosphere for Improved Exo-planetary Spectroscopy
Ground based observations are usually limited to spectral windows between the strong absorptions of atoms and molecules in the terrestrial atmosphere. When observing solar system- and exo-planetary atmospheres these same atomic and molecular absorptions are frequently of interest. To be able to get precise determinations of molecule abundances in planetary observations from ground based telescopes the effects of the Earth's atmosphere need to be accurately removed. This task is complicated by temporal and spatial variations of the terrestrial absorbing species. The strong absorptions by carbon dioxide and water are among the most important and problematic. We have developed new code to work with the highly developed and well-regarded VSTAR radiative transfer atmospheric fitting software to attack this problem. ATMOF‚ATMOspheric Fitting, makes use of VSTAR models of the terrestrial atmosphere as plug-in modules; it uses the Levenberg-Marquardt method to vary the mixing ratios of molecules in the models to fit calibration (standard star observation) data and determine the state of the atmosphere. The terrestrial model is then used to remove telluric absorptions from observations of Titan and the outer planets‚ producing a pure spectrum of these objects. Here we demonstrate the usefulness ATMOF and present spectra processed using it. We make particular comment to its applicability to exo-planetary observations.
Stephen Marsden: Space Weather in Planetary Systems
Our solar system is characterised by a variable solar wind and radiation "space weather" environment. Space weather should also occur in other planetary systems due to the host star's activity, and can now be studied in detail, using observations of activity and magnetism as the basis for computing wind models. This talk will discuss how spectropolarimetry is used to map stellar surface activity and magnetic fields and ! model stellar winds, to offer insights into space weather impacts on planetary systems.
Mike Ireland: The Planet Formation Imager
A variety of precision infrared techniques have recently been detecting young planets and planets in the process of formation. I will review some of these key results, and what enables the high contrast. The next generation of instruments to achieve the highest contrast and see planets in the process of formation will first be a photonic nulling mode of the GMT (prototype funded by a 2014 Discovery grant) and then the Planet Formation Imager (PFI). PFI is the only next generation long-baseline interferometer currently being put forward by the international long-baseline optical and infrared interferometry community. I will describe the broad science case, as well as conceptual design options including an Antarctic interferometer.
Chris Tinney: Mind the 200K gap
I'll talk about some recent results on the properties of the coldest objects we can readily observe (Y-type brown dwarfs at temps down to ~350K) and using them to "fill the gap" between these temperatures, and the ~150K temperatures of Jupiter.
Mark Hutchison: Adding dust to photoevaporation
Photoevaporation is an important dispersal mechanism in protoplanetary disks that successfully explains their observed 'two-time-scale' evolution. However, contrary to what is known about grain growth, settling, and migration, current numerical simulations of photoevaporation neglect the gas-dust interaction by assuming the dust is well mixed with the gas and monodisperse throughout the lifetime of the disk. Correctly accounting for grain growth and dynamics could potentially alter the effects of photoevaporation. I will be presenting a toy model we are developing to investigate the effects that dust can have on photoevaporation.
Jonti Horner: Exoplanets, Dynamics and Habitability
As a direct result of ongoing efforts to detect more exoplanetary systems, an ever-increasing number of multiple-planet systems are being announced. I will present the latest results of our dynamical studies at UNSW, showing how such studies of newly discovered planetary systems can provide critical tests of their stability, and have a role to play in directing the search for further planets in those systems. In the future, such studies will also play an important role in! the determination of the most promising exo-Earths to target in the search for life elsewhere.
Raquel Salmeron: The environment and physics of protoplanetary discs
Protoplanetary discs are the analogues of the early solar system, and potential sites of current planet formation. The most promising mechanisms driving accretion in these systems are turbulent motions driven by the magnetorotational instability and large-scale outflows accelerated from the disc surfaces. Both processes are driven by magnetic fields and are, in turn, likely to strongly affect the structure, evolution and planet-forming processes in the disc. The low ionisation of the material, however, may prevent the magnetic field from driving these processes in some regions of the disc. On the other hand, a record of the formation process of our own solar system is preserved in primitive meteorites, the "building blocks" of the solar nebula. Preserved in these samples are a variety of objects that have experienced very high temperatures (~1700-2000 K) embedded in a matrix that, on the whole, remained cool. The coexistence of hot and cold material in the early solar system his a long-standing puzzle in the field. Magnetic fields, again, may hold the key to explain this issue. In my talk I will present recent results and work in progress in our group on the computation of global, wind-driving disc solutions with realistic microphysics, as well as analysis of the key thermal and dynamical properties of actively-accreting protoplanetary discs and their outflows.
Graeme Salter: Direct Imaging of Anglo-Australian Planet Search Targets
We are finally entering an era where radial velocity and direct imaging parameter spaces are starting to overlap. Radial velocity measurements provide us with a minimum mass for an orbiting companion (the mass as a function of the inclination of the system). By following up these long period radial velocity detections with direct imaging we can determine whether a trend seen is due to an orbiting planet at low inclination of an orbiting brown dwarf at high inclination. In the event of a non-detection we are still able to put a limit on the maximum mass of the orbiting body. The Anglo-Australian Planet Search (AAPS) is one of the longest baseline radial velocity planet searches in existence, amongst its targets are many that show long period trends in the data. As a follow up to an earlier exoplanet workshop I shall give an overview of what we have found from performing direct imaging on these targets with NICI on Gemini South.
Fan Liu: Detailed abundance analysis of the HAT-P-1 stellar binary: constraints on planet formation
A high-precision, differential elemental abundance analysis of the HAT-P-1 stellar binary based on high-resolution, high signal-to-noise ratio Keck/HIRES spectra is presented. The secondary star in this double system is known to host a transiting giant planet with 0.53 Jupiter mass while no planets have yet been detected around the primary star. The derived atmospheric parameters of the HAT-P-1 stellar binary imply that the primary is hotter than the secondary star by 200 K. The metallicities ([Fe/H]) of primary and secondary stars are indistinguishable within the errors: 0.146+/-0.014 dex and 0.155+/-0.007 dex, respectively. Extremely precise differential abundances of 25 elements have been measured (mean error of \sigma([X/Fe]) = 0.013 dex) and are found to be indistinguishable between the two stars (mean difference of [X/Fe] (secondary - primary) = +0.009+/- 0.013 dex). The abundances of each star relative to the Sun show a positive correlation with the condensation temperature of the elements with identical slopes for the two stars; their abundance patterns are thus very similar to those observed in the majority of solar twins. In view of Melendez et al.'s (2009) interpretation of the peculiar solar abundance pattern being due to the presence of terrestrial planets around the Sun, we conclude that HAT-P-1 experienced less efficient formation of terrestrial planets than the Sun. This is in line with the expectation that the presence of close-in giant planets preventing the formation or survival of terrestrial planets. The great similarity in the chemical composition of the two stellar components in HAT-P-1 is contrary to the difference at the 0.05 dex level seen in 16 Cyg A+B, which also hosts a giant planet. We conclude that the presence of giant planets does not automatically imply differences in the chemical compositions of the host stars.
John Greenhill: Searching for exoplanets with the UTas H127 telescope
The new Utas Harlingten 1.27 m telescope will commence searching for exoplanets by microlensing early in 2014. Using the OGLE III wide FOV camera it will be possible to measure ~100 microlensing events at hourly intervals. This will complement observations by OGLE, MOA, Wise and Korean survey telescopes facilitating high cadence, around the clock coverage greatly increasing the frequency of planetary detections. The H127 has two folded Cass focal stations w! ith quick transitions between photometry and spectroscopy. The ex ANU DBS spectrograph will be used at the other focus to determine the classification of M dwarfs. This will facilitate the search, led by the University of Hawaii, for transiting exoplanets capable of supporting life.
Tim Bovaird: Using The Coplanarity of Kepler Systems To Prioritize Titius-Bode Exoplanet Predictions
We use the generalized Titius-Bode (TB) relation to make predictions for the periods of undetected planets in multiple-exoplanet systems. The coplanarity of Kepler systems are investigated to estimate what fraction of our predicted planets are expected to transit their host stars. We prioritize our planet predictions based on their geometric probability to transit. Using this method, we successfully predicted the existence and period of KOI-2722.05 prior to its announcement. Our work has also contributed to the discovery of ~6 Kepler exoplanet candidates through an independent analysis of the Q1-Q15 light curves.
Kim Bott: VSTAR Models of a Hot Jupiter
Past analysis of HD 189733b's atmosphere has been a cause for some debate, with conflicting findings regarding polarised light, carbon dioxide and sodium abundances and the presence of a high altitude haze. We present our model of HD 189733b's atmosphere using VSTAR (Versatile Software for Transfer of Atmospheric Radiation): a robust, line-by-line, multiple scattering radiative transfer solution in a modular program, utilizing its own chemical equilibrium model. Since the effective temperature of the pla! net is expected to be approximately 1100K, newly available high-temperature spectral line lists were used. The planet’s terminator transmission spectrum and dayside thermal emissions and reflection spectrum are modelled and compared to available data.
Rob Wittenmyer: New directions for Exoplanetary Science at UNSW
I give an update on the progress made by the exoplanet team at UNSW in 2013. We have made several new planet discoveries, and I review the status of Minerva, a multi-telescope facility dedicated to finding the smallest planets around the brightest stars. I will also outline plans for engagement with the Kepler 2-wheel mission ("K2") and the Transiting Exoplanet Survey Satellite.
Charley Lineweaver: Terrestrial Planet Habitability
For life forms like us, the most important feature of the Earth is its habitability. Understanding habitability and using that knowledge to locate the nearest habitable planet may be crucial for our survival as a species. Over the past decade, expectations that the universe could be filled with habitable planets have been bolstered by the increasingly large overlap between terrestrial environments known to harbor life and the variety of environments on newly detected rocky exoplanets. The inhabited and uninhabited regions on Earth tell us that temperature and the presence of water are the main constraints that can be used in a habitability classification scheme for rocky planets. Recent exoplanet detections suggests that the fraction of stars with planets is ~ 100%, and that the fraction with rocky planets may be comparably large. We review extensions to the circumstellar habitable zone including an abiogenesis habitable zone and the galactic habitable zone.