Artist's impression of the exoplanet Proxima Centauri b shown as arid (but not completely water-free) rocky Super-Earth. ESO/M. Kornmesser - https://www.eso.org/public/images/ann16056a/

Artist's impression of the system Gliese 667. ESO/L. Calçada - https://www.eso.org/public/images/eso0939a/

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    A multi-parameter approach to habitability (M-PAtH)

    We are standing on the cusp of a major discovery in planetary sciences. Three new space missions targeting transiting planets are expected to launch in the next two years: the Transiting Exoplanet Survey Satellite (TESS), the CHaracterising ExOPlanet Satellite (CHEOPS), and the James Webb Space Telescope (JWST). The 2020’s will bring three 20-40 meter-class ground-based telescopes: the 24.5-meter Giant Magellan Telescope (GMT), the Thirty Metre Telescope (TMT), and the 39.3-meter European-Extremely Large Telescope (E-ELT). The 2020’s will also see space missions such as the Wide-Field InfraRed Survey Telescope (WFIRST), and the PLAnetary Transits and Oscillations of stars (PLATO-2) mission, which will further survey exoplanets. For the first time in human history, these surveys and telescopes working together will be able to remotely detect potential biosignatures in exo-Earth atmospheres and discover signs of life beyond our Solar System.

    Life can be inferred by the presence of atmospheric biomarkers - gases produced by life that can accumulate to detectable levels in an exoplanet atmosphere. The conviction that these biosignatures will be detected by remote sensing from space telescopes is moderated by current time limitations and observational opportunities. The cancellation a decade ago of both the Terrestrial Planet Finder and Darwin missions means that it is unlikely that a space telescope dedicated to the search for biosignatures in exoplanet atmospheres will be launched within the next 15 years (Snellen et al., 2013). While TESS is predicted to significantly increase the number of detections, unfortunately, none of the new space- and ground-telescopes will be solely dedicated to the characterization of exoplanet atmospheres. In order to make the most of the limited observational resources available, optimal target selection will be of the utmost importance. Selection of targets for this characterisation relies on ambiguously defined concepts of habitability, which are currently constrained by only the density of the planet and the distance from its host star. With the expected increase in the number of detected exoplanets from TESS, we might end up with hundreds of planets that suit these criteria and are accordingly all equally likely to host life. Therefore, it is imperative that we rethink our classification of what makes a planet habitable and improve the habitability model using known planetary and astronomical features that offer a broader and more accessible approach than a narrow focus on specific atmospheric signatures.

    My current research aims to examine the effect that a diverse range of astronomical and planetary parameters have on an exoplanet’s ability to sustain liquid water.

Artist's impression of of the exoplanet 51 Pegasi b. ESO/M. Kornmesser/Nick Risinger (skysurvey.org) - https://www.eso.org/public/images/eso1517a/

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Planetary Magnetism as a Parameter in Exoplanet Habitability

Sarah R.N. McIntyre, Charles H. Lineweaver, Michael J. Ireland
Manuscript in Preparation

Abstract

Evidence from the solar system suggests that, unlike Venus and Mars, the presence of a strong magnetic dipole moment on Earth has helped maintain liquid water on its surface. Therefore, planetary magnetism could have a significant effect on the long-term maintenance of atmosphere and liquid water on rocky exoplanets. We use Olson & Christensen's (2006) model to estimate magnetic dipole moments of rocky exoplanets (Rp ≤ 1.23 R). Even when modelling the maximum magnetic dipole moment, only Kepler-186 f has a magnetic dipole moment larger than the Earth's, while 44% ± 16% of rocky exoplanets detected in the circumstellar habitable zone have a negligible magnetic dipole moment. This suggests that planetary magnetism is an important factor when prioritizing observations of potentially habitable planets.

The Evolution of Habitability: Characteristics of Habitable Planets

Charles H. Lineweaver, Aditya Chopra, Sarah R.N. McIntyre
Book Chapter in Press in Vera M. Kolb (Ed.) Handbook of Astrobiology, Taylor & Francis

What biological clocks and geological rocks tell us about life in space

Sarah R.N. McIntyre, Charles H. Lineweaver
Magazine Article The Conversation (13 July 2017)

Abstract

One of the first geological lessons we learn is that continents are constantly moving. The evidence of these plate tectonic movements is written in the rocks. But the rocks only tell us half of the story. The other half is contained in the evolutionary history of animals.

In our recent paper we have made the most comprehensive comparison yet between tectonic plate movements and the evolution of the genes of animals. We found they are in agreement for dating million year old breakup of continents and the divergence of different animal groups.

This result on its own provides further validation regarding the accuracy of both dating methods and is of interest to biologists and geologists.

Global Biogeography Since Pangaea

Sarah R.N. McIntyre, Charles H. Lineweaver, Colin P. Groves, Aditya Chopra
Journal Paper Proceedings Of The Royal Society B: Biological Sciences 284 (1856): 20170716. doi:10.1098/rspb.2017.0716.

Abstract

The break-up of the supercontinent Pangaea around 180 Ma has left its imprint on the global distribution of species and resulted in vicariance-driven speciation. Here, we test the idea that the molecular clock dates, for the divergences of species whose geographical ranges were divided, should agree with the palaeomagnetic dates for the continental separations. Our analysis of recently available phylogenetic divergence dates of 42 pairs of vertebrate taxa, selected for their reduced ability to disperse, demonstrates that the divergence dates in phylogenetic trees of continent-bound terrestrial and freshwater vertebrates are consistent with the palaeomagnetic dates of continental separation.

Abiotic chemical disequilibria in Exo-Earth atmospheres:
improving remote biosignature detections by identifying false positives

Sarah R.N. McIntyre
Master Thesis Australian National University (1 June 2017)

Abstract

We are on the cusp of a technological revolution where near-future space- and ground-based observatories will allow an unprecedented opportunity to explore the atmospheres of potentially habitable exo-Earths for signs of life. Unfortunately, detections of the most significant gases produced by life are also susceptible to false positives. A spectral biosignature can only be positively identified when we know both the probability of life forming it, and perhaps more crucially, the improbability of non-biological (abiotic) processes creating it. Likewise, false negatives in biosignatures are influenced by our bias towards signatures of life on Earth since the Cambrian period. Our understanding of the influence of early life forms on Earth is based on a combination of biochemistry and phylogenetic analyses. In this thesis, we present a comprehensive study of the abiotic chemical disequilibrium discriminators for several proposed biosignature atmospheric gases – O2, O3, CH4, N2O, NH3, SO2, CO2 and H2O. Abiotic environmental factors producing these gases have been identified and will improve our ability to select optimal targets and methods to reduce the effect of false positives. We find that the majority of these false-positive mechanisms are contingent on characteristics of the parent star, particularly the photochemical implications for variation in UV intensity, and are generally strongest for planets orbiting M dwarfs. Additionally, a review of future ground- and space-based projects was conducted to determine exoplanet properties that will become observable over the next decade as these new facilities come on line. In advance of the next generation of telescopes, this appraisal of potential biosignatures and the environmental factors and context that could create false positives, will increase our confidence in the detection of extraterrestrial life.

Terrestrial Constraints on Extraterrestrial Intelligence

Sarah R.N. McIntyre, Charles H. Lineweaver, Colin Groves
Manuscript in Preparation

Abstract

In the pursuit to understand the cosmos and our place within, one question rises above all others: “Are we alone in the universe?” Astronomical research on habitable planets has shown that there are billions of prospective Earth-like planets that could all potentially support complex life forms. However, there is an assumption that permeates through reasoning regarding evolution of life in space that once life is present, even as a single-celled organism, evolution towards human-like intelligence and subsequent technological development is inevitable. This research experimentally investigated the convergent evolution hypothesis to explore if there is an "intelligence niche" towards which, or into which species evolve, and extrapolate how "rare" occurrence of human-like intelligent life is.

Hearing Harmonies in Newton’s Laws

Sarah R.N. McIntyre
Journal Paper Australian Physics Journal, Volume 51, Issue 4, Jul - Aug 2014, Pages 122-124

Abstract

This year, the Australian Institute of Physics Congress theme “The Art of Physics” sets the stage for further investigation into the intrinsic connection between physics and music. This article describes the author’s physics inspired dance suite that will be performed at the AIP Congress in December.

Artist's impression of of the exoplanet Kepler-22b. Credits: NASA/Ames/JPL-Caltech

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Pebble in The Sky: A Biosignature Story

Sarah R.N. McIntyre
Invited Talk A Roadmap for Universal Life, Lorentz Centre, Leiden, Netherlands (29 Oct - 2 Nov 2018)

Multi-Parametar Approach to Habitability

Sarah R.N. McIntyre
Contributed Talk HoRSE : High Resolution Spectroscopy for Exoplanet Atmospheres 2018, Nice, France (1 - 5 Oct 2018)

Habitable Zone ≠ Liquid Water Zone?

Sarah R.N. McIntyre
Poster 18th European Astrobiology Network Association Conference, Berlin, Germany (24 - 28 Sep 2018)

Planetary Magnetism as a Factor of Exoplanet Habitability

Sarah R.N. McIntyre
Contributed Talk European Planetary Science Congress 2018, Berlin, Germany (16 - 21 Sep 2018)

Multi-Parametar Approach to Habitability (M-PAtH)

Sarah R.N. McIntyre
Poster International Workshop on Instrumentation for Planetary Missions, Berlin, Germany (12 - 14 Sep 2018)

Planetary Magnetism as a Factor of Exoplanet Habitability

Sarah R.N. McIntyre
Poster IAU Symposium 345: Origins: From the Protosun to the First Steps of Life, Vienna, Austria (20 - 23 Aug 2018)

A Multi-Parametar Approach to Habitability (M-PAtH)

Sarah R.N. McIntyre
Poster Spectroscopy of Exoplanets, Windsor, UK (8 - 11 Jul 2018)

Planetary Magnetism as a Factor of Exoplanet Habitability

Sarah R.N. McIntyre
Poster Exoplanets II, Cambridge, UK (2 - 6 Jul 2018)

Abiotic chemical disequilibria in Exo-Earth atmospheres:
improving remote biosignature detections by identifying false positives

Sarah R.N. McIntyre
Contributed Talk Astronomical Society of Australia's Annual Scientific Meeting 2017, Canberra, ACT, Australia (9 - 13 Jul 2017)

Terrestrial Constraints on Extraterrestrial Intelligence

Sarah R.N. McIntyre, Charles H. Lineweaver
Contributed Talk Astrobiology Science Conference 2017, Mesa, Arizona, USA (24 - 28 Apr 2017)

Terrestrial Constraints on Extraterrestrial Intelligence

Sarah R.N. McIntyre, Charles H. Lineweaver
Contributed Talk Mt Stromlo Annual Student Seminar, Canberra, Australia (1 - 2 Dec 2016)

Artist’s impression of the planet around Alpha Centauri B. ESO/L. Calçada/Nick Risinger (skysurvey.org) - https://www.eso.org/public/images/eso1241a/

 

  • PhD 2020

    Doctor of Philosophy (Astronomy and Astrophysics)

    Australian National University

    Supervisors: Charles Lineweaver, Michael Ireland, Mark Krumholz, Penelope (Penny) King

    Thesis: A multi-parameter approach to habitability (M-PAtH)

  • AFHEA 2017

    Associate Fellowship of the Higher Education Academy

    ANU Educational Fellowship Scheme



  • B.A.2015

    Bachelor of Arts

    Australian National University

    Major: Biological anthropology
    Major: Music

  • MAA 2017

    Masters Astronomy and Astrophysics (Ad)

    Australian National University

    Supervisor: Charles Lineweaver

    Thesis: Abiotic chemical disequilibria in Exo-Earth atmospheres: improving remote biosignature detections by identifying false positives

  • B.Sc.2015

    Bachelor of Science

    Australian National University

    Major: Physics
    Minor: Mathematics
    Specialization: Astronomy and astrophysics

  • Exchange2015

    Global Programs Exchange

    Niels Bohr Institute University of Copenhagen

    Undergraduate course: Atomic Physics
    Masters course: Origin and Evolution of the Solar System

Artist’s impression of CoRoT-7b. ESO/L. Calçada - https://www.eso.org/public/images/eso0933a/

 

Teaching

  • Feb-Jun 2018

    Lab Demonstrator

    Laboratory Demonstrator for Advanced Physics course (Physics 1101) for First Year students at the Australian National University

  • Jul-Nov 2017

    Lab Demonstrator

    Laboratory Demonstrator for Advanced Physics course (Physics 1201) for First Year students at the Australian National University

  • Feb-Jun 2017

    Lab Demonstrator

    Laboratory Demonstrator for Advanced Physics course (Physics 1101) for First Year students at the Australian National University

Professional Activities

  • Jan-Dec 2018

    RSAA Colloquium Committee member

  • Dec 2017

    FAAbExo 2017 LOC Chair

    Franco-Australian Astrobiology and Exoplanet School and Workshop 16 - 20 Dec 2017, Canberra

Artist’s impression of the planet Beta Pictoris b. ESO L. Calçada/N. Risinger (skysurvey.org) - https://www.eso.org/public/images/eso1414a/