Franco-Australian Astrobiology and Exoplanet School and Workshop

FAAbExo 2017 Workshop Program

# Presentation Speakers Time Venue
WELCOME TO COUNTRY A Welcome to Country Ceremony will
be conducted by Ngunnawal Elder
Tyronne Bell.
09:00 AM - 09:15 AM Weston Theatre
WELCOME ADDRESS A welcome address will be made by
Professor Brian Schmidt AC,
Vice-Chancellor of the
Australian National University.
09:15 AM - 09:30 AM Weston Theatre
1 The Phylogeny of Life on Earth Simonetta Gribaldo
Institut Pasteur
09:30 AM - 10:00 AM Weston Theatre
2 Origin of Life on Earth Martin van Kranendonk
University of New South Wales
10:00 AM - 10:30 AM Weston Theatre
MORNING TEA 10:30 AM - 11:00 AM Crawford School foyer
3 Towards an Understanding of Life on Early Earth:
Microfossils from the c. 2.4 Ga Turee Creek Group,
Western Australia
Erica Barlow
University of New South Wales
11:00 AM - 11:15 AM Weston Theatre
4 The Oxygen Revolution: Life's Evolutionary Response
to Oxygen and What This Could Mean When Looking
for Extra-terrestrial Life
Georgia Soares
University of New South Wales
11:15 AM - 11:30 AM Weston Theatre
5 The Power Without the Glory: Multiple Roles of
Hydrogen Peroxide in Mediating the Origin
of Life on Earth
Rowena Ball
Australian National University
11:30 AM - 11:45 AM Weston Theatre
6 The Gaian Bottleneck Solution to the Fermi Paradox Charley Lineweaver
Australian National University
11:45 AM - 12:00 PM Weston Theatre
LUNCH 12:00 PM - 01:30 PM Crawford School foyer
7 Tides on Exoplanets Inferred by Resonant Chain Architectures Daniel Fabrycky
University of Chicago
01:30 PM - 02:00 PM Weston Theatre
8 Exoplanet Detection Jessie Christiansen
NASA Exoplanet Science Institute
California Institute of Technology
02:00 PM - 02:30 PM Weston Theatre
9 Massive or Not Massive That is the Question Dennis Stello
University of New South Wales
02:30 PM - 02:45 PM Weston Theatre
10 From A Star to Its Rocky Planets:
Devolatilization Matters
Haiyang Wang
Australian National University
02:45 PM - 03:00 PM Weston Theatre
AFTERNOON TEA 03:00 PM - 03:30 PM Crawford School foyer
11 Atmospheric Chemistry and Composition on Venus:
An Overview and Possible Implications for Exoplanets
Franklin Mills
Australian National University
03:30 PM - 03:45 PM Weston Theatre
12 The Long-term Orbital Evolution of Jupiter's Satellite System Christopher Tylor
University of Southern Queensland
03:45 PM - 04:00 PM Weston Theatre
13 Stable Habitable Zones of Jovian Planet Systems Matthew Agnew
Swinburne University
04:00 PM - 04:15 PM Weston Theatre
14 The Provenance of Chondrule Olivine
in Carbonaceous Chondrites
Geoffrey Bonning
Australian National University
04:15 PM - 04:30 PM Weston Theatre
15 Monitoring the Transient Sky With
the Desert Fireball Network
Hadrien Devillepoix
Curtin University
04:30 PM - 04:45 PM Weston Theatre
16 An Atmospheric Remote Sensing
Infrared Exoplanet Large Survey
Vincent Coude du Foresto
Observatoire de Paris
PSL Research University Paris
04:45 PM - 05:15 PM Weston Theatre
POSTER SESSION 05:15 PM - 05:45 PM Crawford School foyer
17 Exoplanet Science at the
University of Southern Queensland
Brad Carter
University of Southern Queensland
05:15 PM - 05:45 PM Crawford School foyer
18 Volcanoes Support Life in Icy Extremes Ceridwen Fraser
Australian National University
05:15 PM - 05:45 PM Crawford School foyer
19 Clotted Microbialites from the 2.4 Ga Turee Creek Group,
Western Australia
Brendan Nomchong
University of New South Wales
05:15 PM - 05:45 PM Crawford School foyer
20 Winds from Protoplanetary Discs James Tocknell
Macquarie University
05:15 PM - 05:45 PM Crawford School foyer

Towards an Understanding of Life on Early Earth: Microfossils from the c. 2.4 Ga Turee Creek Group, Western Australia

It is difficult to know what to look for when searching for life on Mars, or elsewhere in the universe, so we first revert to studying the one example of life that we do know of: that of planet Earth. Life on Earth has been quite complex for at least the past 540 million years, but for over three billion years before that, life consisted of only simple microscopic organisms. Thus, if life were to exist elsewhere, we would expect it to consist of, in the very least, simple microbial forms like those preserved from the early Earth. A recently discovered assemblage of well-preserved microbial fossils from the c. 2.4 Ga Turee Creek Group, Western Australia, provides insight into the diversity of Paleoproterozoic life. Described are eighteen different microfossil morphologies within nodular and bedded black chert units that form the deeper-water portion of a shallow-water stromatolite-thrombolite reef complex. These two black chert facies preserve distinctly different microbial communities: a deeper-water, primarily benthic community in the nodular cherts, and a transported, likely phototrophic, community in the bedded cherts. Combined, this assemblage provides a snapshot of what an ecosystem at c. 2.4 billion years would have looked like. We find a greater diversity in microbial life than what was previously thought to exist at this time. This is a valuable data set for understanding what life on the early Earth would have looked like, and in what types of environments it inhabited, adding to the pool of information that will aid in our search for life elsewhere in the universe.

The Oxygen Revolution: Life's Evolutionary Response to Oxygen and What This Could Mean When Looking for Extra-terrestrial Life

The road to complex life seems to stagnate between the evolution of prokaryotes, confirmed by 3.7 Ga, and the late evolution of eukaryotes at approximately 1.9 Ga. While bacteria and archaea flourished, it seems the driver for new forms of life including non-colonial multicellular life and eukaryotes was absent. The main driver for the evolution of eukaryotes and some early forms of complex multicellularity is thought to be oxygen. Atmospheric oxygen has been available, at least intermittently, since the Great Oxidation Event (GOE) 2.4 billion years ago. So why is it that multicellularity and eukaryotes have been restricted to relatively modern times? New fossil evidence from a 2.4 Ga stromatolite-thrombolite reef that was deposited across the GOE, suggests that multicellularity may not be restricted to the later Proterozoic. These fossils are millimetric, have complex branching and anchoring structures, have kerogen rich walls and siliceous centres. They are unique in a reef dominated by calcium carbonate, and occur within a conglomerate made of chips of phosphorous rich microbial mat and apatite rich peloids. The chips are direct evidence of not only oxygen within the reef, but that these branching structures existed in an oxygen-rich environment. Is it a coincidence that a unique complex looking structure appears at the same time as the first major introduction of oxygen into the atmosphere? Have multicellularity and possibly even eukaryotes evolved much earlier than previously thought? And can we use oxygen as a potential proxy for the evolution of complex life on exoplanets? These complex, organic and branching siliceous structures may allow us some extra insight into answering these questions.

The Power Without the Glory: Multiple Roles of Hydrogen Peroxide in Mediating the Origin of Life on Earth

The story of the relationship between hydrogen peroxide and life is complex and ongoing. Living cells make and break it, and, after a long period when it was reviled as a toxic cell vandal and genetic saboteur, evidence is mounting that its relationship with living organisms is intimate and vital. This is often assumed to have begun with evolution of oxygen-evolving photosynthesis, 2.3 BYA. Yet abiogenic hydrogen peroxide was present on Earth before this, and primitive anaerobes must have come to some arrangement with it. And what of its role with respect to pre- and proto-cellular life, the putative RNA world? In a series of papers1 we have developed and tested the hypothesis that hydrogen peroxide was essential to molecular evolution and development of the RNA world on Earth more than 4 BYA. In this talk I shall synthesise and interpret those works, and ask a key related question: Are we all really vampires? I review the thiosulfate-hydrogen peroxide (THP) redox oscillator, and discuss our simulations of its dynamic interactions with the proto-cellular RNA world. Since life can persist only in a strongly driven, nonequilibrium setting, we examined the effects of normally distributed fluctuating inputs on the outputs of a model for biologically relevant dimerization. We found that a left-skewed, right-weighted probability distribution of fluctuating temperature outputs is essential for sustainable polymerisation, suggesting that the dice on the primordial Earth were loaded in favour of the emergence of life, and effectively giving us the 'fundamental equation of life'.

1. Ball & Brindley: 2015 J. Roy. Soc. Interface 12, 20150366 (doi 10.1098/rsif.2015.0366), 2016 Orig. Life Evol. Biospheres 46, 81 (doi 10.1007/s11084-015-9465-y), 2016 Orig. Life Evol. Biospheres 46, 133 (doi 10.1007/s11084-015-9448-z), 2014 J. Roy. Soc. Interface 11, 20131052 (doi 10.1098/rsif.2013.1052), 2017 Roy. Soc. Open Science 4, 170142 (doi 10.1098/rsos.170141)..

The Gaian Bottleneck Solution to the Fermi Paradox

Exoplanet statistics strongly suggest that rocky Earth-like planets are common and that there is nothing remarkable about the chemical composition of the Earth. The prerequisites and ingredients for life seem to be abundantly available in the Universe. However, we have yet to find any evidence for extraterrestrial life. A common explanation for this is a low probability for the emergence of life (an "emergence bottleneck"), notionally due to the intricacies of the molecular recipe. I will present an alternative Gaian bottleneck explanation (Chopra & Lineweaver 2016): If life emerges on a planet, it only rarely evolves quickly enough to regulate greenhouse gases and albedo, thereby maintaining surface temperatures compatible with liquid water and habitability. Such a Gaian bottleneck suggests that (i) extinction is the cosmic default for most life that has ever emerged on the surfaces of wet rocky planets in the Universe and (ii) rocky planets need to be inhabited to remain habitable. In the Gaian bottleneck model, the maintenance of planetary habitability is a property more associated with an unusual and rapid evolution of biological regulation of surface volatiles than with the luminosity and distance to the host star. During the first billion years of a rocky planets existence there may be no sub-aerial weathering of silicates to produce a negative feedback mechanism for temperature regulation. In the absence of such abiotic negative feedback, a stable circumstellar habitable zone cannot exist.

Massive or Not Massive That is the Question

The study of planet occurrence rates informs our understanding of how planets form. One important aspect is how the occurrence rates depend on stellar mass; however, measuring masses of field stars is often difficult. Over the past decade, a controversy has arisen about the inferred planet occurrence rate around evolved intermediate-mass stars -- the so-called retired A-stars. Particularly, the high masses of these evolved planet hosts, derived using spectroscopic information and stellar evolution models, has been called into question with arguments that they are unlikely to be that high. We aim to resolve the controversy by determining the mass of evolved planet hosting stars using asteroseismology. In this talk I will present our findings based on data from the SONG telescope of bright nearby planet hosting stars. We find a significant one-sided offset between the previous spectroscopy-based masses and our seismic results, suggestive that the former are overestimated.

From A Star to Its Rocky Planets: Devolatilization Matters

As the solar nebula condensed, evaporated and fractionated to form the early Earth, the chemical composition of the bulk Earth was set. To first order, the Earth is a devolatilized piece of the solar nebula. Similarly, rocky exoplanets are almost certainly devolatilized pieces of the stellar nebulae out of which they and their host stars formed. If this is correct, we can estimate the chemical composition of rocky exoplanets by measuring the elemental abundances of their host stars, and then applying a devolatilization algorithm. My work calibrates this potentially universal devolatilization pattern by comparing the bulk elemental abundances of the Sun, the Earth and other solar system bodies. I will present the physical and cosmochemical interpretations to the variables associated with the devolatilization pattern. I will discuss the strong depletion of life-critical volatile elements (C, O, H, N and S) and other depletion mechanisms pertaining to noble gases. The process of devolatilization for Si, Mg, Fe and O has a non-trivial effect on modelling the composition of mantle and core of a rocky planet; that for C and S has profound impact on analyzing the composition of atmosphere and its interaction with the planetary interior. Implications to habitability will be given in using the estimated exoplanetary elemental ratios, such as Mg/Si and C/O.

Atmospheric Chemistry and Composition on Venus: An Overview and Possible Implications for Exoplanets

Venus' atmosphere, which chemically is significantly different from that of the Earth, is one of many possible analogues for exoplanetary atmospheres. Its primary atmospheric consistuent is CO2 but it has chemically significant trace abundances of hydrogen, sulfur, nitrogen, and chlorine compounds that determine what would be potentially observable from outside our Solar System. For example, if the atmosphere had been initially pure CO2 then within a few thousand years the atmosphere would have evolved to be about 90% CO2, 7% CO, and 3.5% O2 because O atoms from dissociation of CO2 preferentially combine to form O2. From outside the Solar System, the portion of Venus' atmosphere that would be observable is the mesosphere. This presentation will review the current understanding of Venus' mesospheric chemistry and discuss the implications for interpretation of exoplanet observations.

The Long-term Orbital Evolution of Jupiter's Satellite System

Jupiter, the Solar system's largest planet, is accompanied by a retinue of satellites, ranging in size from moonlets to planet size bodies. The regular satellites of the Jovian have accompanied the giant planet since the birth of the Solar system. So far only short-term studies of Jupiter's extensive satellite system were conducted. It seems, no simulation has exceeded a timeframe of 105 years. Previous work was mainly focussed on the Galilean moons and the hypothesis of the orbital longevity of the satellite system has never previously been tested. Thus, we explore the long-term orbital evolution of the regular Jovian satellites using numerical modelling with the REBOUND N-body integrator code to assess the potential for significant orbital changes on timescales of tens to hundreds of millions of years. The first phase of this project is to determine the stability of the regular satellites including the Galilean moons. As a result of rather gradual tidal dissipation over a long-time period that has changed their orbital semi-major axes, Io, Europa, and Ganymede are now in an orbital Laplace resonance (1:2:4). So far, our simulation indicates this resonance will have a stabilising effect on the orbits of the Galilean Moons over long time-spans. In the second phase, we will extend the simulation to the whole satellite system of the Jovian, including all known irregular satellites. The results to date indicate that the regular part of Jovian satellite system and particularly the Galilean moons are characterised by an extremely stable orbital configuration.

Stable Habitable Zones of Jovian Planet Systems

With continued improvement in telescope sensitivity and observational techniques, the search for rocky planets in stellar habitable zones is entering an exciting era. With so many exoplanetary systems available for follow-up observations to find potentially habitable planets, one needs to prioritise the ever-growing list of candidates. We aim to determine which of the known planetary systems are dynamically capable of hosting rocky planets in their habitable zones, with the goal of helping to focus future planet search programs. We perform an extensive suite of numerical simulations to identify regions in the habitable zones of single Jovian planet systems where Earth mass planets could maintain stable orbits. We find that small, Earth-mass planets can maintain stable orbits in cases where the habitable zone is largely, or partially, unperturbed by a nearby Jovian, and that mutual gravitational interactions and resonant mechanisms are capable of producing stable orbits even in habitable zones that are significantly or completely disrupted by a Jovian. Our results yield a list of 13 single Jovian planet systems that are not only capable of supporting an Earth-mass planet on stable orbits in their habitable zone, but for which we are also able to constrain the orbits of the Earth-mass planet such that the induced radial velocity signals would be detectable with next generation instruments.

The Provenance of Chondrule Olivine in Carbonaceous Chondrites

Chondrites are accretions of the materials available in the region of the solar protoplanetary disk that they accreted within. Different classes of chondrites host varying proportions of two major components: chondrules, and matrix. Matrix is the fine-grained material that inclusions, such as chondrules, are set within. Chondrules were once free-floating, mm-scale blebs of molten silicates. Their ubiquity in primitive solar system materials suggests that their formation was a widespread process in the protoplanetary disk, though precisely how they formed remains contentious. During their molten phase, they interacted with the surrounding nebular gases, and recorded the conditions of the region of their formation as variations in their chemical and isotopic compositions. As it becomes feasible to place spatial and temporal meaning onto different chondrite classes, the conditions that their inclusions were subjected to will provide valuable constraints on the distribution of physical and chemical environments throughout the protoplanetary disk. In the present work, the chemical and oxygen isotope compositions of olivine in chondrules were examined in situ in three classes of carbonaceous chondrites (CV, CO, and CM) at the population level using an electron microprobe and the Sensitive High Resolution Ion MicroProbe for Stable Isotopes (SHRIMP-SI). Each class of chondrite hosts different proportions of Mg-rich and Fe-rich chondrules, with the Fe-rich chondrules indicative of higher fO2 during formation. The correlation of this higher fO2 with a uniformly heavier oxygen isotope composition in their olivine than in Mg-rich chondrules suggests that Fe-rich chondrules interacted more thoroughly with a reservoir of nebular water. The much wider range of oxygen isotope compositions (a range of ~40 per mille) in Mg-rich chondrules suggest that they sampled a wider range of precursor materials. The implications of these differences between chondrule populations for the protoplanetary disk will be discussed.

Monitoring the Transient Sky With the Desert Fireball Network

The Desert Fireball Network (DFN) is a global distributed observatory designed to track meteoroids entering the atmosphere, determine pre-entry orbits (origin in the solar system), and constrain meteorite fall positions for recovery. Starting with 4 film cameras in 2005, the DFN rapidly recovered 2 meteorites in 2007 and 2010; similar efforts in the Northern hemisphere only yielded a dozen meteorites in over 50 years of operation. The network was then upgraded in 2014 to 52 digital cameras across the continent, and a further 2 meteorites were recovered in 2015 and 2016. The DFN has also established national and international collaborations with 13 partner institutions, installing cameras across the world. This proved rapidly fruitful after a successful meteorite recovery in California in 2015. The DFN is not only expanding globally, but is also able to target other science and industry goals. The robust design and distributed configuration of the established systems can be used with alternate optics to yield 12" pixels over a 375 deg2 field of view, reaching magnitude 13.5 with 5 sec. exposures (down to 15.5 by co-adding 15 mins. of images). The DFN was the only optical instrument on sky at the time of gravitational wave GW170817 and its electromagnetic counterpart, as traditional telescopes were only able to follow-up 10 hours later. This instrument is not limited to passive observation of the most energetic events in the universe, but it can be used in other areas of time domain astronomy: high-cadence long-term light curves on bright stars can easily be obtained; an endeavour that other groups have built special instruments for (eg. for the Beta Pictoris b Hill sphere transit). The wide field of view of the observatories also opens up a new parameter space in space situational awareness, partnering up with industry to do satellite tracking.

An Atmospheric Remote Sensing Infrared Exoplanet Large Survey

The ARIEL mission is an M-class mission within the science program Cosmic Vision of the European Space Agency (ESA), whose launched date is planned for 2026. ARIEL will provide a chemical survey of a large (~1000) sample of warm/hot planetary atmospheres. It will explore systematically the parameter space of size, temperature and density for the planets, as well as stellar type and metallicity for their host stars. Its product will therefore enable insight into the correlations and interplay between planetary and stellar compositions as well as evolution. Because the target stars of the ARIEL sample are bright they will be amenable for preparatory study from the ground, notably through high angular resolution techniques.

Exoplanet Science at the University of Southern Queensland

Stellar astronomy and planetary systems research at USQ aims to advance understanding of the shared evolution of stars and planets, and the implications for life. A particular focus is the combination of stellar magnetic field and exoplanet studies to investigate the impact of stellar activity and winds on exoplanetary systems, and the implications for habitability. USQ's Mt Kent Observatory is also now getting the MINERVA-Australis optical telescope array that will support the NASA Transiting Exoplanet Survey Satellite (TESS) in its mission to detect and characterise exoplanets around solar neighbourhood stars. The relatively nearby exoplanets expected to be detected should provide added targets for our studies of stellar activity and its planetary impacts.

Volcanoes Support Life in Icy Extremes

Antarctica looks like a frozen wasteland, yet the continent is home to diverse life. Wherever there is ice-free land, small plants and animals thrive. We're currently in a relatively warm period in Earth's recent history, but 20,000 years ago, at the peak of the Last Glacial Maximum, temperatures were much lower, and Antarctica's glaciers were much larger, even extending to the edge of the continental shelf in some areas. There should not have been any ice-free land available - yet we know from genetic analyses that many Antarctic species and lineages are unique, and so must have remained in Antarctica for millions of years. How could terrestrial mosses and invertebrates possibly have survived Pleistocene glaciations in Antarctica? Antarctica has more than 100 volcanoes, many of which are known to have been active for tens, and possibly hundreds, of thousands of years. Volcanic areas in Antarctica can be relatively warm, with steam melting ice around summits and fumaroles, and hollowing out caves beneath the glaciers. Could volcanoes could hold the key to the long-term survival of life in Antarctica? Evidence from my research group suggests they probably do: species richness analyses, for example, show that there are many more species close to volcanoes than further away. We have also found traces of DNA from diverse plants and invertebrate animals in geothermal caves on volcanic Mount Erebus in Antarctica. Could the growing recognition that volcanoes have helped life survive in extreme Earth environments (such as Antarctica) help us to look for life on icy planets and moons?

Clotted Microbialites from the 2.4 Ga Turee Creek Group, Western Australia

Microbialites are fossil rocks produced by simple bacterial life on Earth, the oldest of which are simple stromatolitic tufts from 3.7 Ga metasediments in Greenland. Through time, microbialite morphologies developed into more complex forms, including: branching structures; giant bioherms; and non-laminated textures. The Great Oxidation Event (GOE) at c. 2.45-2.32 Ga marked a major milestone in Earth's atmospheric evolution, when oxygen began to accumulate in the atmosphere. This period has also been linked to significant developments in biological evolution, such as an increase in cyanobacteria diversity and the rise of multicellularity. Researchers recently described a new dolomite microbialite reef from the 2.4 Ga Turee Creek Group (TCG), WA, that displays complex microbialite morphologies including the oldest occurrence of a clotted, rather than laminated, microbialite. It has since been revealed that this TCG clotted microbialite represents a diverse suite of both biogenic and abiogenic carbonate textures, the classification of which is the subject of this research. We identified four main types of clotted carbonate, including three primary biogenic textures. These include: a unique clotted microbial aggregate that formed during periodic high energy events; massive beds of clotted microbialite that grade through wrinkly microbial mats into stromatolites; the oldest described true thrombolites; and multiple diagenetic carbonate textures, including recrystallised microbial mats and recrystallised clotted microbialite. Our research confirms that new expressions of clotted microbial growth, including the earliest described occurrence of thrombolites in the rock record, coincided with the GOE. This presents the question: Was this increase in microbial complexity driven by global environmental change, specifically by the appearance of atmospheric oxygen on early Earth? Future research on this paleo-ecosystem will address this question, the answer of which would have implications for our understanding of how life evolved on Earth, and how it could potentially have evolved elsewhere in the universe

Winds from Protoplanetary Discs

Magnetically-driven disc winds have significant effects on the evolution of protoplanetary discs, via the removal of angular momentum and mass from the disc. However, existing models typically ignore non-ideal magnetohydrodynamic effects, such as Hall drift, but these are known to operate inside these discs, and affect their structure and evolution, for example suppressing magnetically-driven turbulence and magneto-rotational instability. In my talk, I will present preliminary results of self-similar disc wind models which include non-ideal magnetohydrodynamic effects within the disc.

# Presentation Speakers Time Venue
1 Structure and Stability of Planetary Systems Jacques Laskar
Remote from France
Observatoire de Paris
PSL Research University Paris
09:00 AM - 09:30 AM Weston Theatre
2 New Technologies for Exoplanet Detection Frantz Martinache
Observatoire de la Cote d'Azur
09:30 AM - 10:00 AM Weston Theatre
3 Direct Exoplanet Detection with Novel
Pre-ELT Instruments
Mike Ireland
Australian National University
10:00 AM - 10:15 AM Weston Theatre
4 Exoplanetary Science with Veloce Rosso at the AAT Christoph Bergmann
University of New South Wales
10:15 AM - 10:30 AM Weston Theatre
MORNING TEA 10:30 AM - 11:00 AM Crawford School foyer
5 Status Update and Future of the HATSouth project Joao Bento
Australian National University
11:00 AM - 11:15 AM Weston Theatre
6 Astrophysical Standards for FunnelWeb's
Label-based Stellar Parameter Pipeline
Adam Rains
Australian National University
11:15 AM - 11:30 AM Weston Theatre
7 Searching for Young Exoplanets with
High-Contrast Imaging in the Near Infrared
Alexander Wallace
Australian National University
11:30 AM - 11:45 AM Weston Theatre
8 New Metrics to Study Spectral Line Profile Jinglin Zhao
University of New South Wales
11:45 AM - 12:00 PM Weston Theatre
LUNCH 12:00 PM - 01:00 PM Crawford School foyer
Excursion to Deep Space Communication Complex 01:00 PM - 05:30 PM Tidbinbilla
Mt Stromlo - ANU Campus Transfer Drop-off the participants that will
not attend dinner.
Pick-up participants that did not attend
the excursion, but will attend dinner.
06:00 PM ANU Campus
WORKSHOP DINNER 06:30 PM - 9:30 PM Mt Stromlo
Observatory
Mt Stromlo - ANU Campus Transfer Drop-off the participants after dinner. 10:00 PM ANU Campus

Direct Exoplanet Detection with Novel Pre-ELT Instruments

Direct detection of light from exoplanets is the only way to characterise atmospheres at typical solar-system separations, or in "habitable" zones for all but the smallest host stars. Detection rates from current adaptive optics instrument have not met expectations, largely because massive Jovian planets are uncommon at the >10AU separations probed by these instruments. Specialist instrumentation for exoplanet detection on extremely large telescopes are not scheduled for first light, with the possible exception of METIS. I will describe with reference to simulations two key instrument concepts for direct exoplanet detection relevant to Australia's new strategic partnership with ESO: the Hi-5 nulling instrument for the VLTI, as a precursor for the planet formation imager, and the possibility for high dispersion coronagraphy for reflected light exoplanet technology on a VLT. These instruments will be able to detect young exoplanets at solar system scales, and directly detect reflected light from habitable-zone planets orbiting low mass stars.

Exoplanetary Science with Veloce Rosso at the AAT

The next-generation high-resolution echelle spectrograph for the AAT, Veloce Rosso, is currently being built and is expected to go into operation in early 2018. With a Menlo Systems astro-comb for simultaneous wavelength calibration, a wavelength coverage from about 600 to 900 nm, a focal plane segmenting IFU, and a temperature and pressure stabilised design, Veloce Rosso will provide sub-m/s radial-velocity precision and will thus enable a new level of Doppler exoplanet science in Australia. Amongst our principal science goals are the follow-up of potentially habitable exoplanets discovered by the NASA K2 and TESS satellites, the search for solar system analogues around the most stable stars, and the search for habitable zone planets, especially around faint low-mass M-dwarfs. However, Veloce Rosso can also be used as a general-purpose instrument for high-resolution spectroscopic observations. After giving an overview of the instrument's design and capabilities, and the plans for its science exploitation, I will discuss some aspects of the approach to the data reduction process in the light of what is required to obtain sub-m/s radial velocity precision.

Status Update and Future of the HATSouth Project

The HATSouth Exoplanet survey is the largest ground based dedicated survey systematically searching for planetary transits. This project consists of three near identical facilities located in Chile, Namibia and Australia and is capable of covering 8x8 deg fields for 24 hours a day. With 36 planets already published and another 23 confirmed planets with papers in preparation, the capabilities of this project are well determined and characterised and it is time to look into the future in the TESS era. In this talk I will give a short summary and status update of the project, as well as discuss some of the unique aspects that make this facility and its archival data an excellent complementary tool for TESS data.

Astrophysical Standards for FunnelWeb's Label-based Stellar Parameter Pipeline

The FunnelWeb Survey, using the TAIPAIN instrument on the UK-Schmidt telescope at Siding Spring Observatory, seeks to create a new database of spectra for every Southern Hemisphere star down to 12th magnitude. FunnelWeb will grow the number of stars with high-quality (S/N~100), moderate resolution (R~2000) spectra available in a calibrated and on-line database. The main goals of the survey include a spectral library with detailed stellar parameters (including Teff, log(g), [Fe/H] and [alpha/Fe]), an input catalogue for the TESS satellite, and identifications of young stars through Li. This talk details requirements and processes for selecting stellar standards to serve as the basis for FunnelWeb's label based stellar parameters pipeline.

Searching for Young Exoplanets with High-Contrast Imaging in the Near Infrared

Direct imaging of exoplanets is limited by the optics of the telescope which need to be removed by deconvolution or subtraction of point spread functions (PSFs.) In this project, existing methods of image analysis are tested with a large sample of young stars imaged by Keck, especially in the Taurus association, to search for companions. I am working on a new analysis method in which an ideal PSF is created using a linear combination of images of calibration stars. This will work towards the ultimate goal of establishing new sensitivity limits for planet detection and, in the event of any clear detections, improving our understanding of planet formation.

New Metrics to Study Spectral Line Profile

In the game of radial velocity detection of exoplanets, it's a great challenge to tell if an apparent spectral line shift is caused by gravitationally bound companions (e.g. planets) that result in a bulk motion of the lines or stellar variability that results in intrinsic spectral line deformation. We investigate new metrics (e.g. Gauss-Hermite decomposition, Fourier transform) in an effort to extract stellar rotation period and planet orbital period information, with the ultimate aim to quantify radial velocities caused by stellar variability.

# Presentation Speakers Time Venue
1 Direct Imaging of Planets Anne Marie Lagrange
Remote from France
Institut de Planetologie
et d'Astrophysique de Grenoble
09:00 AM - 09:30 AM Weston Theatre
2 Geophysics of Rocky Planets Diana Valencia
University of Toronto
09:30 AM - 10:00 AM Weston Theatre
3 High-pressure Silicate Phases in Exoplanets:
Implications for Dynamics and Thermal Evolution
Craig O'Neill
Macquarie University
10:00 AM - 10:15 AM Weston Theatre
4 Hostile SuperEarths and the Ladder of Life Geoff Davies
Australian National University
10:15 AM - 10:30 AM Weston Theatre
MORNING TEA 10:30 AM - 11:00 AM Crawford School foyer
5 Diffraction-limited Polarimetric Imaging of Protoplanetary
Disks and Dusty Circumstellar Regions with VAMPIRES
Barnaby Norris
University of Sydney
11:00 AM - 11:15 AM Weston Theatre
6 Nulling Interferometry for High Contrast,
High Resolution Imaging of Substellar Companions
Tiphaine Lagadec
University of Sydney
11:15 AM - 11:30 AM Weston Theatre
7 Exoplanet Science from Space Platforms: TOLIMAN and JWST Peter Tuthill
University of Sydney
11:30 AM - 11:45 AM Weston Theatre
8 Detecting and Characterizing Earth-like Exoplanets from Space Jens Kammerer
Australian National University
11:45 AM - 12:00 PM Weston Theatre
LUNCH 12:00 PM - 01:30 PM Crawford School foyer
9 Retention of Hydrogen Atmosphere on SuperEarths David Stevenson
California Institute of Technology
01:30 PM - 02:00 PM Weston Theatre
10 Ab Initio Equations of States for Planetary
and Exoplanetary Modeling: The Case of Jupiter
Stephane Mazevet
PSL Research University Paris
02:00 PM - 02:30 PM Weston Theatre
11 The Emerging Knowledge of Early Life from the Oldest
(>3600 million year old) Rock Record
Vickie Bennett
Australian National University
02:30 PM - 02:45 PM Weston Theatre
12 HD142527: A Crime Scene Investigation Daniel Price
Monash University
02:45 PM - 03:00 PM Weston Theatre
AFTERNOON TEA 03:00 PM - 03:30 PM Crawford School foyer
13 Direct Mapping of the Temperature and Velocity
Gradients in Protoplanetary Discs
Christophe Pinte
Monash University
03:30 PM - 03:45 PM Weston Theatre
14 Tiny Grains Shining Bright in the
Gaps of Herbig Ae Transition Discs
Eloise Birchall
Australian National University
03:45 PM - 04:00 PM Weston Theatre
15 Binary Star Formation and the Outflows from their Discs Rajika Kuruwita
Australian National University
04:00 PM - 04:15 PM Weston Theatre
16 Kinematic Ages of Stellar Associations Tim Crundall
Australian National University
04:15 PM - 04:30 PM Weston Theatre
17 Soft astronomy: Tidal evolution and Spin dynamics
of rocky and icy bodies
Alice Quillen
University of Rochester
04:30 PM - 04:45 PM Weston Theatre

High-pressure Silicate Phases in Exoplanets: Implications for Dynamics and Thermal Evolution

The evolution of silicate-mantle exoplanets is sensitive to the rheology high-pressure silicate phases. For the Earth, these are present as in the lower mantle as the perovksite-structured mineral bridgmanite, and ferripericlase. Ferripericlase is three orders of magnitude weaker than bridgmanite under equivalent conditions, and mixing laws suggest that the small variations in the proportion of these two constituents can have a large effect on mantle viscosity. In addition, bridgmanite can transition into a denser post-perovskite near the core-mantle boundary, for low-temperatures, such as those within subducted slabs. It has been suggested this phase may be orders of magnitude weaker than bridgmanite, and may play an important role in the dynamics of the bottom thermal boundary layer. These silicate phases are expected to be present over a wide-range of conditions for the interiors of superEarths, due to higher internal pressures. Here we explore numerical models to assess the importance of the dynamics of these phases in the thermal evolution of the interior of exoplanets, and the way it in which this interior evolution manifests itself on the surface

Hostile SuperEarths and the Ladder of Life

'Earth-like' planets more than 1.5-2 times Earth's mass may be hostile to life. For this and other reasons, although life may be not uncommon, multicellular life may be extremely rare. A rocky Earth-like planet more massive than Earth will have a steep pressure gradient through its mantle that will greatly increase the viscosity at depth. This will hinder convective heat removal from depth by the large-scale overturn operating within Earth. The resulting build-up of heat may lead either to occasional catastrophic mantle overturns or to a 'heat pipe' mechanism resulting in super plumes and semi-continuous super-heated super-eruptions. Io seems to exhibit the latter mode on a small scale. Either could make the persistence of life difficult. Loose talk about whether 'life' might exist on a planet is commonly over-interpreted to imply multi-cellular, intelligent or even 'civilised' life, but this fails to consider the multiple levels of complexity of life on Earth. Life seems to be a plausible result of chemical self-organisation through auto-catalytic cycles, given some basic ingredients and suitable conditions. It is therefore not unreasonable to infer that some basic form of life may be not uncommon, though still on a quite small minority of planets. However life on Earth exhibits at least six major levels of emergence, each building complexity upon the previous level. On this ladder, multicellular organisms are the fifth level and took around two billion years to emerge. Social systems or large brains represent a higher level of emergence and another billion-year gestation. Smaller rocky planets may not be so common, and Earth's extraordinarily stable environment may be highly unusual. Large organisms would then be unlikely and self-aware brains drastically less likely. Bipedal Spocks and Yodas would of course absurdly unlikely.

Diffraction-limited Polarimetric Imaging of Protoplanetary Disks and Dusty Circumstellar Regions with VAMPIRES

VAMPIRES is a high-angular-resolution interferometric imager developed to directly image dusty planet-forming disks around young stars, and mass-loss regions around evolved stars. It is currently deployed at the Subaru telescope as part of the SCExAO system. VAMPIRES leverages aperture masking interferometry - providing diffraction-limited imaging despite seeing - in combination with fast-switching differential polarimetry, to directly image structure in the inner-most regions of these systems (using the polarisation properties of scattered starlight) at milliarcsecond scales. It has recently been upgraded to include a spectral differential imaging mode, wherein imaging in H\alpha (or other emission-line) takes place simultaneously with an adjacent continuum band, allowing differential imaging to reveal accreting regions in protoplanetary disks. New high-speed acquisition and polarization-switching modes allow high precision full-pupil polarization-differential imaging. In addition to an overview of the instrument and observing capabilities, recent on-sky science results and performance results will be presented.

Nulling interferometry for High Contrast, High Resolution Imaging of Substellar Companions

With many thousands exoplanets discovered one of the important next steps in astronomy is to be able to characterise them. This presents a great challenge and calls for new observational capabilities with both high angular resolution and extreme high contrast in order to efficiently separate the bright light of a host star to that of a faint companion. Glint is a prototype instrument developed at the University of Sydney that uses photonic technology to perform nulling interferometry. The light of a star is cancelled out by means of destructive interference in a tiny photonic chip, letting through only the light of a potential companion. One of the challenges GLINT presents is the star light injection into the chip. This is done by a unique active system that optimises the injection and provide low order correction for the atmospheric turbulence. In this talk I will report on the latest progresses with GLINT following tests of the instrument and observations of few bright stars at the Anglo Australian Telescope.

Exoplanet Science from Space Platforms: TOLIMAN and JWST

NASA's forthcoming flagship astronomy mission, the James Webb Space Telescope (JWST), launches in 2019 with an innovative interferometer instrument aboard designed at the University of Sydney. With more than 30 hours assigned already to this operational mode in GTO time, several key programs targeting exoplanetary science will be supported. Sydney is also leading a study in support of the TOLIMAN mission which aims to deliver sub-microarcsecond astrometry enabling detection of earth-analogs around the Alpha Centuri system. This is a 30cm highly stable space telescope with a planned 3-year mission lifetime. Current status and prospects for both projects will be reviewed.

Detecting and Characterizing Earth-like Exoplanets from Space

Looking at ESA's Cosmic Vision roadmap, there is no large mission dedicated to exoplanet science. However, from a purely scientific point of view, a space-based telescope for the detection and characterization of nearby Earth-like exoplanets would offer an unprecedented sample of several hundreds of directly detected companions with sub-Neptunian sizes. In this talk, I will illustrate the capabilities of a formation-flying mid-infrared nulling interferometer in terms of planet yield based on planet occurrence statistics from Kepler. The dependence on planetary albedos, orbital eccentricity, exozodiacal light and errors in the Kepler statistics will be discussed and the results are compared to a large aperture, optical/near-infrared space telescope.

Ab Initio Equations of States for Planetary and Exoplanetary Modeling: The Case of Jupiter

Using ab initio molecular dynamics simulations, we recently calculated the equations of state for the main constituents of planetary interiors: H, He, H2O, MgSiO3(MgO,SiO2) and Fe. These equations of states are multi-phases, include liquid and solid states, and aim at building planetary and exoplanetary interior models solely based on ab initio predictions. This talk will concentrate on Jupiter. We will review how our current understanding of the behavior of these basic constituents at extreme density temperature conditions has modified our current understanding of Jupiter interior, not only for the envelop where metallization of hydrogen and hydrogen-helium demixing is the issue but also for the core where the high pressure melting properties of iron, water and silicates bring a new understanding on the nature of giant planet cores. This work is supported in part by the French Agence National de la Recherche under contract PLANETLAB ANR-12-BS04-0015 and the PSL IRIS project Origins and Conditions for the Emergence of Life.

The Emerging Knowledge of Early Life from the Oldest (>3600 million year old) Rock Record

Rare Eoarchean (>3600 Ma) to Hadean (>4000 Ma) rocks are our terrestrial "planetary" samples; they provide the ground-truth for models of early Earth formation, environments and chemical evolution. Intensive investigations by many groups reveal rocks of this age comprise only one millionth of Earth's surface and are found in 9 areas of varying extent distributed worldwide. This record is of variable fidelity however, owing to metamorphic (heating to > 500°C) overprinting. The majority of the oldest rocks are high grade gneisses originally formed at mid-crustal depths; the more rare metasedimentary rocks and metabasalts formed at shallow levels and directly reflect early Earth's surface conditions and processes. First-order observations of rocks from 3.6 Ga to ≥ 3.9 Ga provide abundant evidence of liquid water at the Earth's surface with chemical sedimentary rocks in the form of cherts, banded Fe formations and sedimentary carbonates. In the best preserved sections of ancient rocks, located in Isua, southwest Greenland, evidence for ancient life is found within 3,700-Myr-old metacarbonate rocks that contain recently discovered 1- 4 cm-high stromatolites - macroscopically layered structures produced by microbial communities (Nutman et al, 2016). These stromatolites grew in a shallow marine environment, as indicated by their trace element patterns that strongly resemble modern seawater compositions, and by the presence of interlayered detrital sedimentary rocks with cross-lamination and storm-wave generated breccias. This complements other evidence for life in this area the form of stable isotope signatures of C in graphite (e.g. Rosing, 1999). The sophistication of life by 3,700 Ma indicated by the stromatolites is in accord with genetic molecular clock studies placing life's origin in the Hadean eon (>4,000 Ma).

Nutman, V. Bennett, C.R.L. Friend, M. Van Kranendonk and A. Chivas (2016), Nature, 537 (535-538). Rosing, M. T. (1999), Science 283, 674-676.

HD142527: A Crime Scene Investigation

Whodunnit? Why is there a cavity, spiral arms, crazy radial flows, warps, shadows and a giant dust banana in HD142527? In this brief episode of CSI I will examine the evidence, look for clues and ultimately name the culprit. You can run, but you can't hide.

Direct Mapping of the Temperature and Velocity Gradients in Protoplanetary Discs

Accurate measurements of the physical structure of protoplanetary discs are critical inputs for planet formation models. Such constraints are traditionally established via complex modelling of continuum and line observations. Instead, we presented a general framework to measure directly the altitude, velocity and temperature of the CO emitting layers in protoplanetary discs at intermediate inclination. These simple geometrical considerations were applied to IM Lupi, where we report the first direct, i.e., model-independent, measurements of the radial and vertical gradients of temperature and velocity in a protoplanetary disc. We also directly map the vertical CO snow line, which is located at about one gas scale height at radii between 150 and 300 au, with a CO freeze-out temperature of 21 K. In the outer disk, the velocity rotation field becomes significantly sub-Keplerian, in agreement with the expected steeper pressure gradient. The sub-Keplerian velocities should result in a very efficient inward migration of large dust grains, explaining the lack of millimetre continuum emission outside of 300 au. Because these measurements are performed directly on the ALMA channel maps and do not rely on any modelling of the disc, they put unbiased constraints on the disc structure, which, in turn, are critical to feed models of disc structure, dust evolution, and early stages of planet formation.

Tiny Grains Shining Bright in the Gaps of Herbig Ae Transition Discs

Protoplanetary discs exhibit structures such as rings, gaps, asymmetries, and spiral arms, which can be interpreted as signs of planet formation. Around Herbig Ae stars such as Oph IRS 48 and HD 169142, these structures are prevalent in the outer disc regions. In this work, we examine the regions inward of approximately 20AU, where these discs are thought to be mostly cleared of material. We find that there resolved rings of emission that are bright in the near-infrared. We also recover asymmetries in the discs. The inner disc structures are made up of very small dust grains, and in some cases these inner structures could be interpreted as planets.

Binary Star Formation and the Outflows from their Discs

We carry out magnetohydrodynamical simulations with FLASH of the formation of a single, a tight binary (a ~2.5AU) and a wide binary star (a ~ 45AU). We study the outflows and jets from these systems to understand the contributions the circumstellar and circumbinary discs have on the efficiency and morphology of the outflow. In the single star and tight binary case we obtain a single pair of jets launched from the system, while in the wide binary case two pairs of jets are observed. This implies that in the tight binary case the contribution of the circumbinary disc on the outflow is greater than that in the wide binary case. We also find that the single star case is the most efficient at transporting mass, linear and angular momentum from the system, while the wide binary case is an order of magnitude less efficient. The tight binary's efficiency falls between the other two cases, but converges towards the single star case when considering the angular momentum transport. By studying the magnetic field structure we deduce that the outflows in the single star and tight binary star case are magnetocentrifugally driven, whereas in the wide binary star case the outflows are driven by a magnetic pressure gradient.

Kinematic Ages of Stellar Associations

Many difficulties in understanding the timeline of protoplanetary disk evolution and subsequently planet formation stem from imprecise age measurements of the host stars. In this talk I showcase a new technique to utilise kinematic data (position, parallax, proper motions and radial velocity) of members of moving groups to find stellar ages that are independent of stellar models. Moving groups (stellar associations) are collections of stars that, despite being spatially separated, share a common motion, e.g. β Pictoris moving group or TW Hya Association. With the dawn of hyper accurate (proper motion uncertainty < 0.1 μas/yr, RV uncertainty < 0.5 km/s, parallax uncertainty < 0.3 mas), ultra-faint (G < 20 mag), all sky kinematic catalogues (Gaia, Gaia-ESO, Gallah etc) we will have an unprecedented wealth of 6-dimensional kinematic data. We use this data to project the orbits of moving group members back in time through the galactic potential. Using a Bayesian statistical approach we calculate the time in the past corresponding to the moving groups' smallest occupied volume and thus its origin point, providing an age for all known members.

Soft astronomy: Tidal evolution and Spin dynamics of rocky and icy bodies

With springs inserted into an N-body simulation, we can simulate tidal evolution of solid moons and planets, directly tying simulated viscoelastic rheology to spin and orbital drift and tidally generated internal heat distribution. Long simulations of the minor satellites in a drifting Pluto-Charon binary system exhibit rich resonant spin dynamics, including spin-orbit resonance capture, tumbling resonance and spin-binary resonances. We found a spin precession resonant mechanism capable of lifting obliquities, effective in the Pluto/Charon system, too slow to tilt a young Uranus, but might operate in multiple exoplanet systems. We find that the internally generated heat distribution in tidally locked and librating systems is sensitive to crustal material properties, perhaps causing development of asymmetric crust thickness as the body cools.

Crawford School of Public Policy

132 Lennox Crossing, Canberra, ACT, Australia

Astrobiology & Exoplanet School

16 - 17 December 2017

Astrobiology & Exoplanet Workshop

18 - 20 December 2017

Our Sponsors

Australian National University College of Science Research School of Astronomy & Astrophysics Research School of Earth Sciences
Embassy of France in Australia Creative France Australia Australian-French Association for Research and Innovation Paris Sciences et Lettres Research University

16 - 20 December, 2017

Crawford School of Public Policy,
132 Lennox Crossing,
Canberra, ACT, Australia