
Australian Exoplanet Workshop Organising Committee Programme Registration Participants Venue and Accommodation Contact Us


Abstracts Michael Ireland: Direct Detection of Extrasolar Planets at the Highest Angular Resolution Detecting extrasolar Jupiter-like planets at separations of 5-20 AU is difficult for radial velocity techniques due the long orbital periods involved, and is difficult for coronagraphy techniques, because of the small angular separations involved. This range of initial separations is important, as it defines the boundary between regimes where core-accretion and gravitational instability models can most easily form extrasolar giant planets. I will describe the kernel-phase and aperture-mask interferometry techniques that operate in this regime around stars in nearby star forming regions, and will report on the recent discovery of a planet in the process of formation around LkCa 15. Rob Wittenmyer: The Pan-Pacific Planet Search: Exploring new parameter space with the AAT With more than 600 extrasolar planets now known, it is critically important to expand our efforts into new regions of parameter space. At the Anglo-Australian Telescope, we have begun the Pan-Pacific Planet Search, a survey of Southern evolved, intermediate-mass stars in collaboration with John Johnson's Lick and Keck survey of Northern subgiants. This all-sky survey of over 600 stars will significantly improve our knowledge of the frequency of planets orbiting stars more massive than the Sun. I also describe a planned observational campaign to quantify the lack of short-period planets orbiting intermediate-mass stars. Finally, I also describe plans to expand Australian planet-search efforts to late M stars, around which no planets have yet been detected. Taken together, these projects push the frontiers of exoplanet parameter space toward lower-mass planets and higher-mass host stars, which will contribute to a more complete understanding of planet formation by better characterising the population of exoplanets. Graeme Salter: Revealing Exoplanets - Post Processing Methods for Direct Observation In this talk I wish to inform the audience of three methods of post processing that can be used to directly observe exoplanets. Angular Differential Imaging (ADI), which is currently the most favourable post processing method due to the instrumentation available and the success of HR8799. Simultaneous Differential Imaging (SDI), which has had less success but can be used in combination with ADI on some instruments. Spectral Deconvolution (SD) which looks to be able to provide far greater contrasts but requires the use of an integral field spectrograph and therefore will not be able to achieve its full potential until new instruments come online (GPI, SPHERE and eventually EPICS). Karen Lewis: Does Realistic Photometric Noise Affect Our Ability To Find Moons of Transiting Planets? The photometric transit timing technique was proposed by Szabó et.al. (2006) as a method for discovering moons of transiting extra-solar planets. In the preliminary analysis of this technique, it was assumed that the noise in the transit lightcurve was well described by uncorrelated white noise. Unfortunately, real stellar lightcurves contain an excess of lower frequency compon! ents due to processes such as supergranulation and granulation. To determine the effect of using more realistic lightcurves, timing uncertainties using both additive white noise and solar lightcurves from the SoHO data archive were calculated and compared. It was found that moons of planets with long transit durations, were dramatically less detectable when realistic stellar noise was used than when white noise of the same power was used. Jade Carter-Bond: The Composition of Exo-Earths The details of the formation of the terrestrial planets are long-standing questions in the geological, planetary and astronomical sciences, with the discovery of extrasolar planetary systems placing even greater emphasis on these questions. Here we present simulations of the bulk compositions of simulated terrestrial planets in extrasolar planetary systems. These simulations incorporate both giant planet migration into the dynamical simulations and a variety of ices, clathrates and hydrates into the chemical modeling, providing us with a more inclusive view of extrasolar terrestrial planet formation. We find that a diverse range of extrasolar terrestrial planets are produced, ranging from bulk elemental compositions similar to that of Earth to those that are enriched in elements such as C and Si, producing planets with compositions unlike anything we have previously observed. These variations in composition will greatly influence planetary processes such as plate tectonics, planetary interior structure and the primary atmospheric composition. Sarah Maddison: Detecting planet gaps in disks with ALMA The Atacama Large Millimetre/submillimetre Array (ALMA) will have the resolution to observe a planetary gap created by a Jupiter-mass planet in a protoplanetary disk. In the sub-mm and mm wavelengths, is the grains in the size range 10 µm to 1 cm which are the dominant contributors to the thermal emission. For standard parameters of a T Tauri disk, grains of this size range are weakly coupled to the gas (leading to vertical settling and radial migration) and the common approximation of "well-mixed" gas and dust does not hold. In this work, we provide predictions for ALMA observations of planet gaps that account for the specific spatial distribution of dust that results from consistent gas+dust dynamics. Using results from our 3D, two-fluid Smoothed Particle Hydrodynamics (SPH) simulations of a planet embedded in a gas+dust T Tauri disk, we follow the formation and evolution of a planetary gap for various planet masses and grain sizes. The resulting dust distributions are passed to the Monte Carlo radiative transfer code MCFOST to construct synthetic images in the ALMA wavebands. We then use the ALMA simulator to produce images that include thermal and phase noise for a range of angular resolutions, wavelengths, and integration times, as well as different source inclinations, declinations and distances. We come these results with images produced assuming the gas and dust are well-mixed to compare with previous ALMA predictions. We clearly demonstrate the importance of correctly incorporating the dust dynamics, and find that the gap carved by a 1 Mj planet orbiting at 40 AU is visible with a much higher contrast than the well-mixed assumption would predict. In the case of a 5 Mj planet, we clearly see a deficit in dust emission in the inner disk, and point out the risk of interpreting the resulting image as that of a transition disk with an inner hole if observed in unfavorable conditions. We find that planet signatures are fainter in more distant disks but declination and inclination have little effect on ALMA’s ability to resolve the gaps. We conclude that signposts of planets in disks should be routinely seen by ALMA in nearby star-forming regions and we present optimized observing parameters to detect them. Simon O'Toole: SPADES and the Amateur-Professional exoplanet connection The Search for Planets Around Detached Eclipsing Systems is a collaboration between professional and amateur astronomers to search for circumbinary planets similar to Kepler 22b using small telescopes and off-the-shelf cameras. I will present the motivation for the project and an update on its status. Francesco Pignatale: Water vapour, protoplanetary dust and extrasolar planets Grain in protoplanetary disk constitute the building blocks of meteorites, comets and planets. Their formation and composition is strictly related to the chemistry of gas and dust in the disk. Thermodynamic modelling associated with observation of stellar photospheres, protoplanetary and debris disks, is a powerful method to understand and predict the bulk chemistry of extrasolar planets. We utilize a chemical equilibrium code to study the effect of different initial compositions in the condensation process, which occurs in a protoplanetary disk during the formation of the first solids. In this talk I will demonstrate the vital role that water vapour plays for different C/O ratios in determining the resulting grains and extrasolar planet's bulk composition. Sarah Keith: Magnetic Fields in Giant Planet Formation Magnetic fields play a fundamental role in the formation of giant planets, and are at the heart of current theories of accretion. Within these models the viscosity required for inflow is provided by magnetically induced turbulence (caused by the magnetorotational instability). The fields may also drive outflows, which carry angular momentum away from the disk-planet system. Whether the magnetic field is able to interact sufficiently with the circumplanetary disk to govern this transport of momentum remains a key question in planet formation theory. In order to determine this an understanding the magnetic field-disk interaction is needed. Although significant headway has been made in understanding the impact of magnetic coupling in protoplanetary disks, little of this knowledge has been applied to circumplanetary disks. As a first step, I examine the nature and effectiveness of magnetic coupling in circumplanetary disks. I demonstrate that circumplanetary disks are well coupled to magnetic fields. I present disk temperature profiles, ionisation levels, and magnetic diffusivities calculated assuming a standard alpha-disk model, and incorporating the effects of dust grains. Jeremy Bailey: Modelling Exoplanet Spectra using VSTAR I will describe the VSTAR atmospheric modelling software, which is capable of predicting the spectra of a wide range of objects including Solar system planets, exoplanets, brown dwarfs and M dwarfs. VSTAR uses a line-by-line approach to molecular absorption using a database of more than 2.9 billion spectral lines. This is combined with a full multiple scattering treatment of radiative transfer. I will describe the tests that have been used to verify correct operation, and present examples of applications to a range of objects. Raquel Salmeron: The dynamical and thermal environment of planet formation 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. 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). In contrast, the preservation of presolar grains in meteorites, geochemical evidence for a poorly-mixed nebula, and astrophysical observations of forming stars suggest a cool protoplanetary disc, where temperatures are too low to produce this thermal processing. The coexistence of hot and cold material in the early solar system has remained unexplained for many decades. Magnetic fields, again, may hold the key to solve this long-standing puzzle in planetary science. In my talk I will briefly examine the meteoritic record, key thermal and dynamical properties of actively-accreting protoplanetary discs and the implications for planet formation. I will also present our recent results on the thermal processing of solid material in wind-driving protoplanetary discs. Duane Hamacher: Engaging School Students in the Search for Extrasolar Planets The search for exoplanets is one of the most active areas of astronomy and one that garners substantial public interest. Thus, exoplanetary science is ideal for promoting astronomy in schools, specifically among high school students with some basic knowledge of physics and computing. Traditionally, the primary technique for finding exoplanets has been the Doppler (Radial Velocity) Method. However, this technique does not reveal the diameter or actual mass (and hence, density) of the host planet. Since there is roughly a 10% chance that a Hot Jupiter-type planet will transit its host star, stars exhibiting planet-like wobbles need to be checked for signatures of a transit. High school students can use published radial velocity data to predict when transits are expected for each star, model each light curve for a planet transit given the star's magnitude and spectral type, and determine the best time of year to observe each star. With this information in hand, students could use a dedicated telescope to search the stars for transits. These observations would provide useful data, as transiting planets will reveal a wealth of information about each system and a null result (no transit) would constrain the minimum mass of the planet. The software for such a project is readily available and dedicated telescopes with fully automated data reduction pipelines are in place. This will allow students to engage in hands-on astronomical research and develop critical thinking and writing skills, planting the seeds of the next generation of professional astronomers. Chris Tinney: Exoplanetary Science at UNSW UNSW hosts exoplanetary research in a wide variety fields. In addition to the long-running Anglo-Australian Planet Search, we also undertake theoretical simulations of the dynamics of exoplanetary systems hosting multiple planets, as well as the formation and chemical abundance of terrestrial planets. In addition we host imaging programs searching for companions to AAPS stars, as well as free-floating planets in young stars clusters. UNSW is also home to the new CYCLOPS and CYCLOPS2 facilities for spectroscopy with UCLES at the AAT, which we will be using for transit planet science from 2012 onwards. Yitping Kok: Astrometry as a potential exoplanet search technique and SUSI Ever since the discovery of the first exoplanet about two decades ago,various techniques have been introduced to search for more such worlds. Astrometry is another potential technique which looks for reflex motion of stars in the sky due to presence of nearby companions. However such motion is tiny. The reflex motion of a Solar-mass star induced by a Jupiter-mass planet with a 5AU orbital radius at a distance of 100pc away is no more than 100 micro-arcseconds. Although currently no astronomical instrument is able to detect stellar motion of this scale, several, including one at the Sydney University Stellar Interferometer (SUSI), are already being built. This talk will compare the various instruments, their capabilities and lastly give an update on the development at SUSI. Stephen Parker: Methane Imaging surveys of nearby clusters T dwarfs are amongst the coolest and least massive compact astrophysical objects that we can directly observe outside our Solar System. They share many properties with the expanding population of known exoplanets (most of which are inaccessible to direct observation themselves). Understanding T dwarf atmospheres, therefore, is crucial for expanding our understanding of exoplanets. T dwarf surveys in young star clusters can provide us with samples of T dwarfs for which age and distance - both critical for comparing observations with models - are known. My research has focused on performing two such surveys: one of Corona Australis (d ~ 170pc, age ~ 3Myr) and another of IC2391 (d ~ 150pc, age ~ 50Myr). The latest results from these surveys will be presented. Duncan Wright: The CYCLOPS fibre-feed to to UCLES and it's application to RV planet searching CYCLOPS is a Cassegrain-fed optical-fibre bundle, that replaces the 5 mirror Coude train that injects light into the UCLES spectrograph. It reformats a ~3" diameter aperture into a pseudo-slit which is 0.63" wide and 15 elements long, allowing it to deliver similar throughput to the old mirror train, but with improved spectral resolution (λ/Δλ=70000 compared to 45000 with a 1" slit) and from an aperture equivalent to a 2.45" diameter, which better matches typical AAT seeing conditions than a 1" slit. I will discuss the performance of CYCLOPS in terms of throughput and precision as well as the specialised data reduction method to obtain the highest precision data. Additionally I will mention some of the current applications of CYCLOPS and the plans for the upcoming CYCLOPS-2. Daniel Bayliss: The HAT-South Survey for Transiting Exoplanets I will outline the HAT-South survey for transiting exoplanets, in particular focusing on the Australian contributions to the project. Lucyna Kedziora-Chudczer: Detection and characterization of exoplanets by using polarization measurements Light scattered from planetary surfaces and atmospheres is linearly polarized in contrast to the light coming directly from the parent star. High sensitivity polarimeters can potentially detect planets and help to characterize their atmospheric composition. In particular, polarimetric observations of the 'glint' spot can reveal the existence of liquid water on the planet. I will discuss the observable effects, which affect the degree of linear polarization as a function of orbital phase. Brett Addison: Spin-orbit alignment of transiting planetary systems from RM effect observations using CYCLOPS Over 700 extrasolar planets have been discovered over the last decade and a half with many more to be discovered in the next couple of years. In addition to discovering new extrasolar planets, a detailed analysis of their structure, composition, and other bulk properties is also needed in order to gain an understanding of the processes involved in the formation of planets in other systems as well as in our own solar system. The Exoplanetary Science group at UNSW is commissioning a Cassegrain-fed optical-fiber bundle called CYCLOPS at the Anglo-Australian Telescope (AAT) to carry out Doppler spectroscopy of transiting planet candidate stars arising from Southern Hemisphere transit searches. In addition, our team will carry out measurements of the Rossiter-McLaughlin (RM) effect in transiting exoplanets. The RM effect is a spectroscopic anomaly in the radial velocity curve that arises when a planet occults a small spot on the rotating disk of its host star. This in turn causes asymmetric distortions in the line profiles of a star's spectrum creating the apparent anomaly seen in the radial velocity curve. The detection of this effect allows us to estimate the spin-orbit alignment of transiting planetary system, which is a critical component in order to study the processes involved in planetary formation and migration. Mark Wardle: On Dead Zones in Protoplanetary Disks The destabilising effect of Hall diffusion in a weakly-ionised, Keplerian disc allows the magnetorotational instability (MRI) to occur for much lower ionisation levels than would otherwise be possible. I illustrate the critical effect of Hall diffusion on the extent of dead zones in protoplanetary disks by applying a local stability criterion to a simple model of the minimum-mass solar nebula at 1 AU, including x-ray and cosmic-ray ionisation and a population of 1 micron-sized grains. Hall diffusion increases or decreases the MRI-active column density by an order of magnitude or more, depending on whether B is parallel or antiparallel to the rotation axis, respectively. Existing estimates of the depth of magnetically active layers in protoplanetary discs based on damping by ohmic diffusion are likely to be wildly inaccurate Tim Bedding: Asteroseismology of planet-hosting stars with Kepler NASA's Kepler mission is discovering hundreds of transiting exoplanet systems. In some of these, the host star is bright enough for its oscillations to be detected in the Kepler light curve. This allows us to apply the powerful methods of asteroseismology, which can provide accurate radii, masses and ages for the host stars. In the best cases, the inclination of the stellar rotation axis to the line of sight can also be measured from the oscillations. Jonti Horner: Dynamical Simulations: Constraining Multiple-Planet Exoplanetary Systems As a direct result of ongoing efforts to detect more exoplanetary systems, an ever-increasing number of multiple-planet systems are being announced. But how many of these systems are truly what they seem? In many cases, such systems are announced solely on the basis of orbital fits to observational data, and no attempt is made to see whether the proposed orbits are actually dynamically feasible. As a result, it is certain that planetary systems are being announced , that involve planets moving on orbits that would be dynamically unstable on timescales of just a few hundred years. Here, we present the results of detailed dynamical simulations following the evolution of a number of recently discovered exoplanetary systems. These simulations have enabled us to create highly detailed dynamical maps of those systems, allowing us to better constrain the orbits of the planets contained therein. In one case, our results even lead to the very existence of the planets themselves being called into question. Martin Asplund: The imprint of planet formation in the chemical composition of stars

Abstracts

Michael Ireland

Detecting extrasolar Jupiter-like planets at separations of 5-20 AU is difficult for radial velocity techniques due the long orbital periods involved, and is difficult for coronagraphy techniques, because of the small angular separations involved. This range of initial separations is important, as it defines the boundary between regimes where core-accretion and gravitational instability models can most easily form extrasolar giant planets. I will describe the kernel-phase and aperture-mask interferometry techniques that operate in this regime around stars in nearby star forming regions, and will report on the recent discovery of a planet in the process of formation around LkCa 15.

Rob Wittenmyer

With more than 600 extrasolar planets now known, it is critically important to expand our efforts into new regions of parameter space. At the Anglo-Australian Telescope, we have begun the Pan-Pacific Planet Search, a survey of Southern evolved, intermediate-mass stars in collaboration with John Johnson's Lick and Keck survey of Northern subgiants. This all-sky survey of over 600 stars will significantly improve our knowledge of the frequency of planets orbiting stars more massive than the Sun. I also describe a planned observational campaign to quantify the lack of short-period planets orbiting intermediate-mass stars. Finally, I also describe plans to expand Australian planet-search efforts to late M stars, around which no planets have yet been detected. Taken together, these projects push the frontiers of exoplanet parameter space toward lower-mass planets and higher-mass host stars, which will contribute to a more complete understanding of planet formation by better characterising the population of exoplanets.

Graeme Salter

In this talk I wish to inform the audience of three methods of post processing that can be used to directly observe exoplanets. Angular Differential Imaging (ADI), which is currently the most favourable post processing method due to the instrumentation available and the success of HR8799. Simultaneous Differential Imaging (SDI), which has had less success but can be used in combination with ADI on some instruments. Spectral Deconvolution (SD) which looks to be able to provide far greater contrasts but requires the use of an integral field spectrograph and therefore will not be able to achieve its full potential until new instruments come online (GPI, SPHERE and eventually EPICS).

Karen Lewis

The photometric transit timing technique was proposed by Szabó et.al. (2006) as a method for discovering moons of transiting extra-solar planets. In the preliminary analysis of this technique, it was assumed that the noise in the transit lightcurve was well described by uncorrelated white noise. Unfortunately, real stellar lightcurves contain an excess of lower frequency compon! ents due to processes such as supergranulation and granulation. To determine the effect of using more realistic lightcurves, timing uncertainties using both additive white noise and solar lightcurves from the SoHO data archive were calculated and compared. It was found that moons of planets with long transit durations, were dramatically less detectable when realistic stellar noise was used than when white noise of the same power was used.

Jade Carter-Bond

The details of the formation of the terrestrial planets are long-standing questions in the geological, planetary and astronomical sciences, with the discovery of extrasolar planetary systems placing even greater emphasis on these questions. Here we present simulations of the bulk compositions of simulated terrestrial planets in extrasolar planetary systems. These simulations incorporate both giant planet migration into the dynamical simulations and a variety of ices, clathrates and hydrates into the chemical modeling, providing us with a more inclusive view of extrasolar terrestrial planet formation. We find that a diverse range of extrasolar terrestrial planets are produced, ranging from bulk elemental compositions similar to that of Earth to those that are enriched in elements such as C and Si, producing planets with compositions unlike anything we have previously observed. These variations in composition will greatly influence planetary processes such as plate tectonics, planetary interior structure and the primary atmospheric composition.

Sarah Maddison

The Atacama Large Millimetre/submillimetre Array (ALMA) will have the resolution to observe a planetary gap created by a Jupiter-mass planet in a protoplanetary disk. In the sub-mm and mm wavelengths, is the grains in the size range 10 µm to 1 cm which are the dominant contributors to the thermal emission. For standard parameters of a T Tauri disk, grains of this size range are weakly coupled to the gas (leading to vertical settling and radial migration) and the common approximation of "well-mixed" gas and dust does not hold. In this work, we provide predictions for ALMA observations of planet gaps that account for the specific spatial distribution of dust that results from consistent gas+dust dynamics. Using results from our 3D, two-fluid Smoothed Particle Hydrodynamics (SPH) simulations of a planet embedded in a gas+dust T Tauri disk, we follow the formation and evolution of a planetary gap for various planet masses and grain sizes. The resulting dust distributions are passed to the Monte Carlo radiative transfer code MCFOST to construct synthetic images in the ALMA wavebands. We then use the ALMA simulator to produce images that include thermal and phase noise for a range of angular resolutions, wavelengths, and integration times, as well as different source inclinations, declinations and distances. We come these results with images produced assuming the gas and dust are well-mixed to compare with previous ALMA predictions. We clearly demonstrate the importance of correctly incorporating the dust dynamics, and find that the gap carved by a 1 Mj planet orbiting at 40 AU is visible with a much higher contrast than the well-mixed assumption would predict. In the case of a 5 Mj planet, we clearly see a deficit in dust emission in the inner disk, and point out the risk of interpreting the resulting image as that of a transition disk with an inner hole if observed in unfavorable conditions. We find that planet signatures are fainter in more distant disks but declination and inclination have little effect on ALMA’s ability to resolve the gaps. We conclude that signposts of planets in disks should be routinely seen by ALMA in nearby star-forming regions and we present optimized observing parameters to detect them.

Simon O'Toole

The Search for Planets Around Detached Eclipsing Systems is a collaboration between professional and amateur astronomers to search for circumbinary planets similar to Kepler 22b using small telescopes and off-the-shelf cameras. I will present the motivation for the project and an update on its status.

Francesco Pignatale

Grain in protoplanetary disk constitute the building blocks of meteorites, comets and planets. Their formation and composition is strictly related to the chemistry of gas and dust in the disk. Thermodynamic modelling associated with observation of stellar photospheres, protoplanetary and debris disks, is a powerful method to understand and predict the bulk chemistry of extrasolar planets. We utilize a chemical equilibrium code to study the effect of different initial compositions in the condensation process, which occurs in a protoplanetary disk during the formation of the first solids. In this talk I will demonstrate the vital role that water vapour plays for different C/O ratios in determining the resulting grains and extrasolar planet's bulk composition.

Sarah Keith

Jeremy Bailey

I will describe the VSTAR atmospheric modelling software, which is capable of predicting the spectra of a wide range of objects including Solar system planets, exoplanets, brown dwarfs and M dwarfs. VSTAR uses a line-by-line approach to molecular absorption using a database of more than 2.9 billion spectral lines. This is combined with a full multiple scattering treatment of radiative transfer. I will describe the tests that have been used to verify correct operation, and present examples of applications to a range of objects.

Raquel Salmeron

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. 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). In contrast, the preservation of presolar grains in meteorites, geochemical evidence for a poorly-mixed nebula, and astrophysical observations of forming stars suggest a cool protoplanetary disc, where temperatures are too low to produce this thermal processing. The coexistence of hot and cold material in the early solar system has remained unexplained for many decades. Magnetic fields, again, may hold the key to solve this long-standing puzzle in planetary science. In my talk I will briefly examine the meteoritic record, key thermal and dynamical properties of actively-accreting protoplanetary discs and the implications for planet formation. I will also present our recent results on the thermal processing of solid material in wind-driving protoplanetary discs.

Duane Hamacher

The search for exoplanets is one of the most active areas of astronomy and one that garners substantial public interest. Thus, exoplanetary science is ideal for promoting astronomy in schools, specifically among high school students with some basic knowledge of physics and computing. Traditionally, the primary technique for finding exoplanets has been the Doppler (Radial Velocity) Method. However, this technique does not reveal the diameter or actual mass (and hence, density) of the host planet. Since there is roughly a 10% chance that a Hot Jupiter-type planet will transit its host star, stars exhibiting planet-like wobbles need to be checked for signatures of a transit. High school students can use published radial velocity data to predict when transits are expected for each star, model each light curve for a planet transit given the star's magnitude and spectral type, and determine the best time of year to observe each star. With this information in hand, students could use a dedicated telescope to search the stars for transits. These observations would provide useful data, as transiting planets will reveal a wealth of information about each system and a null result (no transit) would constrain the minimum mass of the planet. The software for such a project is readily available and dedicated telescopes with fully automated data reduction pipelines are in place. This will allow students to engage in hands-on astronomical research and develop critical thinking and writing skills, planting the seeds of the next generation of professional astronomers.

Chris Tinney

UNSW hosts exoplanetary research in a wide variety fields. In addition to the long-running Anglo-Australian Planet Search, we also undertake theoretical simulations of the dynamics of exoplanetary systems hosting multiple planets, as well as the formation and chemical abundance of terrestrial planets. In addition we host imaging programs searching for companions to AAPS stars, as well as free-floating planets in young stars clusters. UNSW is also home to the new CYCLOPS and CYCLOPS2 facilities for spectroscopy with UCLES at the AAT, which we will be using for transit planet science from 2012 onwards.

Yitping Kok

Ever since the discovery of the first exoplanet about two decades ago,various techniques have been introduced to search for more such worlds. Astrometry is another potential technique which looks for reflex motion of stars in the sky due to presence of nearby companions. However such motion is tiny. The reflex motion of a Solar-mass star induced by a Jupiter-mass planet with a 5AU orbital radius at a distance of 100pc away is no more than 100 micro-arcseconds. Although currently no astronomical instrument is able to detect stellar motion of this scale, several, including one at the Sydney University Stellar Interferometer (SUSI), are already being built. This talk will compare the various instruments, their capabilities and lastly give an update on the development at SUSI.

Stephen Parker

T dwarfs are amongst the coolest and least massive compact astrophysical objects that we can directly observe outside our Solar System. They share many properties with the expanding population of known exoplanets (most of which are inaccessible to direct observation themselves). Understanding T dwarf atmospheres, therefore, is crucial for expanding our understanding of exoplanets. T dwarf surveys in young star clusters can provide us with samples of T dwarfs for which age and distance - both critical for comparing observations with models - are known. My research has focused on performing two such surveys: one of Corona Australis (d ~ 170pc, age ~ 3Myr) and another of IC2391 (d ~ 150pc, age ~ 50Myr). The latest results from these surveys will be presented.

Duncan Wright

CYCLOPS is a Cassegrain-fed optical-fibre bundle, that replaces the 5 mirror Coude train that injects light into the UCLES spectrograph. It reformats a ~3" diameter aperture into a pseudo-slit which is 0.63" wide and 15 elements long, allowing it to deliver similar throughput to the old mirror train, but with improved spectral resolution (λ/Δλ=70000 compared to 45000 with a 1" slit) and from an aperture equivalent to a 2.45" diameter, which better matches typical AAT seeing conditions than a 1" slit. I will discuss the performance of CYCLOPS in terms of throughput and precision as well as the specialised data reduction method to obtain the highest precision data. Additionally I will mention some of the current applications of CYCLOPS and the plans for the upcoming CYCLOPS-2.

Daniel Bayliss

I will outline the HAT-South survey for transiting exoplanets, in particular focusing on the Australian contributions to the project.

Lucyna Kedziora-Chudczer

Light scattered from planetary surfaces and atmospheres is linearly polarized in contrast to the light coming directly from the parent star. High sensitivity polarimeters can potentially detect planets and help to characterize their atmospheric composition. In particular, polarimetric observations of the 'glint' spot can reveal the existence of liquid water on the planet. I will discuss the observable effects, which affect the degree of linear polarization as a function of orbital phase.

Brett Addison

Over 700 extrasolar planets have been discovered over the last decade and a half with many more to be discovered in the next couple of years. In addition to discovering new extrasolar planets, a detailed analysis of their structure, composition, and other bulk properties is also needed in order to gain an understanding of the processes involved in the formation of planets in other systems as well as in our own solar system. The Exoplanetary Science group at UNSW is commissioning a Cassegrain-fed optical-fiber bundle called CYCLOPS at the Anglo-Australian Telescope (AAT) to carry out Doppler spectroscopy of transiting planet candidate stars arising from Southern Hemisphere transit searches. In addition, our team will carry out measurements of the Rossiter-McLaughlin (RM) effect in transiting exoplanets. The RM effect is a spectroscopic anomaly in the radial velocity curve that arises when a planet occults a small spot on the rotating disk of its host star. This in turn causes asymmetric distortions in the line profiles of a star's spectrum creating the apparent anomaly seen in the radial velocity curve. The detection of this effect allows us to estimate the spin-orbit alignment of transiting planetary system, which is a critical component in order to study the processes involved in planetary formation and migration.

Mark Wardle

The destabilising effect of Hall diffusion in a weakly-ionised, Keplerian disc allows the magnetorotational instability (MRI) to occur for much lower ionisation levels than would otherwise be possible. I illustrate the critical effect of Hall diffusion on the extent of dead zones in protoplanetary disks by applying a local stability criterion to a simple model of the minimum-mass solar nebula at 1 AU, including x-ray and cosmic-ray ionisation and a population of 1 micron-sized grains. Hall diffusion increases or decreases the MRI-active column density by an order of magnitude or more, depending on whether B is parallel or antiparallel to the rotation axis, respectively. Existing estimates of the depth of magnetically active layers in protoplanetary discs based on damping by ohmic diffusion are likely to be wildly inaccurate

Tim Bedding

NASA's Kepler mission is discovering hundreds of transiting exoplanet systems. In some of these, the host star is bright enough for its oscillations to be detected in the Kepler light curve. This allows us to apply the powerful methods of asteroseismology, which can provide accurate radii, masses and ages for the host stars. In the best cases, the inclination of the stellar rotation axis to the line of sight can also be measured from the oscillations.

Jonti Horner

As a direct result of ongoing efforts to detect more exoplanetary systems, an ever-increasing number of multiple-planet systems are being announced. But how many of these systems are truly what they seem? In many cases, such systems are announced solely on the basis of orbital fits to observational data, and no attempt is made to see whether the proposed orbits are actually dynamically feasible. As a result, it is certain that planetary systems are being announced , that involve planets moving on orbits that would be dynamically unstable on timescales of just a few hundred years. Here, we present the results of detailed dynamical simulations following the evolution of a number of recently discovered exoplanetary systems. These simulations have enabled us to create highly detailed dynamical maps of those systems, allowing us to better constrain the orbits of the planets contained therein. In one case, our results even lead to the very existence of the planets themselves being called into question.

Martin Asplund

Last Updated: Sep 03 2012