Dr Cormac R. Purcell

Intelligent Systems for Planetary Good



I'm interested in all sorts of data-driven science with benefits for humanity and the natural world. Lately, the focus of my work has moved from astronomy to Earth-science and remote sensing.

Some of my projects are summarised below and my papers can be accessed via the following services:

Bushfire Systems

Severe wildfires are becoming increasingly common as a direct result of anthropomorphic climate change. We need to radically improve our fire prevention and management systems worldwide. Artificial intelligence and Earth-observation data can help ameliorate fire risk, detect fires earlier, support live firefighting operations and help with recovery. However, we need to understand where to concentrate development efforts for maximum impact.

The team at Trillium Technologies has worked with key Australian fire agencies to produce a new report on Bushfire Systems and Situational Awareness. The report presents a system-level overview of bushfire management in Australia, with a particular focus on fireground operations. We identify challenges and significant pain points experienced by active firefighters, and show how technology might solve issues in the near future.

Bushfire Systems Report: [Web Page] [PDF]

Bushfire Data Quest 2020: [Web Page] [Proceedings]

Trillium Australia: https://www.trilliumaustralia.tech

Machine Learning In Orbit

Earth-observation data is extremely powerful for a host of tasks: determining land use, hydrology, measuring flood extent, detecting wildfires - and many more. However, it takes up to 48 hours to download raw data from satellites and process it into a usable form. What if we could move the processing steps onto the satellite (or constellation of satellites) and rapidly download small and insightful data directly to end-users?

Trillium and FDL, in partnership with D-Orbit, Unibap and ESA Phi Lab, recently demonstrated the operation of a new Machine Learning (ML) Payload in orbit. The ML Payload implements the WorldFloods neural network to create vector-maps of flood extent, sending these to the ground within 15 minutes of image acquisition.

Presentation Video: [YouTube] (5 min)

Press Release: [PDF]

Partners: [ESA] [D-Orbit] [Unibap] [Oxford]

Monitoring Sharks Using Drones

Human-shark conflict, development and climate change present ongoing threats to shark populations in Australian coastal waters. Although rare, shark bites are traumatic events, so the NSW government has made shark management and environmental monitoring a research priority.

Our team from from Sci-eye and the NSW Department of Primary Industries have created intelligent software to detect and identify shark species in live video from shark-spotting drones. The Sharkie App incorporates advanced machine learning techniques and operates on Android mobile devices, without needing an internet connection.

The project was started at Macquarie University with a MQNS Grant and compute support from Fujitsu Australia. Ongoing development by Sci-eye is supported by funding from the NSW Government.

More Information: Project Page

Fujitsu Blog: Harnessing AI For Ocean Health

Paper: The Drone Revolution of Shark Science

Sci-eye: https://scieye.com.au

The Gum Nebula and its Environment

The Gum Nebula is 36 degree wide shell-like emission nebula at a distance of only 450 pc. It has been hypothesised to be an old supernova remnant, fossil HII region, wind-blown bubble, or combination of multiple objects. In this project we investigated the magneto-ionic properties of the nebula and its impact on the interstellar medium using data from recent surveys: radio-continuum data from the NRAO VLA and S-band Parkes All Sky Surveys, and H-alpha data from the Southern H-Alpha Sky Survey Atlas.

By analysing rotation measures through the nebula, and by fitting a simple model, we were able to measure the geometry and strength of the local ordered magnetic field. The fitted compression factor at the edge strongly supports the explanation that the nebula is an ionised HII shell around a wind-blown bubble.

Paper: [ADS] [arXiv]


High-mass stars (> 8 M) form deep inside giant molecular clouds that block all visible light. These young stars ionise their surroundings, creating bubbles of hydrogen that emit radio waves. Long-wavelength radiation can escape the clouds, so mapping the radio-sky is the best way to answer the fundamental question: How many high-mass stars are there in the Milky Way?

The Co-Ordinated Radio 'N' Infrared Survey for High-mass star formation, or CORNISH, is the radio-continuum counterpart of the mid-infrared Spitzer GLIMPSE project. Observations on the Karl Jansky Very Large Array yielded a high resolution map of the northern Galactic plane at 5 GHz wavelengths - and the most complete census of ultra-compact HII regions to-date.

Website: http://cornish.leeds.ac.uk

Paper 1: [ADS] [arXiv]

Paper 2: [ADS] [arXiv]

Paper 3: [ADS] [arXiv]

Paper 4: [ADS] [arXiv]

HOPS: a survey of the Galactic Plane

The H2O southern Galactic Plane Survey (HOPS) mapped 100 square degrees of the sky, detecting molecules that emit at wavelengths around 2-cm. Observations on the Mopra telescope targeted a 1-degree wide strip of the Galactic Plane, searching for ammonia and bright water masers. These molecules trace the peaks of giant molecular clouds and regions where gas is violently shocked: the cradles of young stars.

Our observations resulted in a 3-D map showing the distribution and Doppler shift of dense gas in the Galaxy. By matching Doppler shift to Galactic rotational velocity, we created a top-down map of the Milky Way's spiral arms - a highly useful finder chart for future projects investigating star formation.

Website: https://research.science.mq.edu.au/hops

Paper 1: [ADS] [arXiv]

Paper 2: [ADS] [arXiv]

Paper 3: [ADS] [arXiv]

Triggered Star-formation in NGC 3576

The star-forming region NGC 3576 is a spectacular example of a wave of star-birth sweeping through a giant molecular cloud. At the heart of cloud lies a giant ionised bubble, generated by a cluster of young high-mass stars. Previous observations have shown that the bubble is embedded in clumpy filament of cool dust, prompting the question: Is star-formation being triggered or quenched in the dusty cloud?

To answer this question we used the Australia Telescope Compact Array (ATCA) and Mopra radio telescopes to map NGC 3576 in a suite of molecules: NH3, CO, HCO+, CS, N2H+ and H2O. The resulting maps of temperature and chemistry reveal that star-formation is underway across the whole filament, likely triggered by the expansion of the central bubble.

Paper: [ADS] [arXiv]

Methanol Masers and Hot Molecular Cores

Stars are formed from collapsing clumps of gas and dust at the heart of giant molecular clouds. This process takes at least 100,000 years, so we can only observe a 'snapshot' of stars forming in the Galaxy. Astronomers study the physics of star-formation by finding many examples with a range of ages and then order them on a timeline.

During my PhD I investigated the 'weather' and chemistry towards methanol masers - signposts to young high-mass stars. Using the Mopra radio telescope I measured the abundance of key organic molecules, proving the link between the early hot molecular core phase of high-mass star-formation and 6.67 GHz CH3OH masers.

Paper 1: [ADS] [arXiv]

Paper 2: [ADS] [arXiv]

Commissioning the Mopra Telescope

The Mopra Observatory is a 22-m radio-telescope operated by the Australia Telescope National Facility and located at the edge of the Warrumbungle Mountains, near Coonabarabran, NSW, Australia. Radio telescopes like Mopra measure the 'brightness temperature' of gas in their beam (field of view) and make maps by scanning back-and-forth across the sky.

This work to measure the shape of the beam and calibrate the brightness scale paved the way for Mopra to make spectacular 3D-maps of molecular clouds in the southern Galactic Plane: RCW106, Nessie, and many more.

Paper: [ADS]

Astronomy Presentations

These older presentations on astronomy and analysis techniques may be useful to some.

Magnetism: Earth to the Cosmos
Public talk, ASNSW, 2017

Magnetism & the Gum Nebula
ASTRON Colloquium 2015

Radiation as a Physical Probe
Harley Wood Winter School 2012
[Slides] [Notes]

PhD Thesis on Star Formation

My PhD thesis "What's in the Brew? A study of the molecular environment of methanol masers and UCHII regions." was was accepted by the UNSW School of Physics in February 2007. The four main science chapters were published as refereed papers, linked in the projects above.

Thesis Document: [PDF] (14 MB)

LaTeX Code: [Tarball] (21 MB)

Star Formation Diagram: [PNG] [Tarball: SVG, PDF, PNG]