Studying the spaces between to understand star formation
Dr Chenoa Tremblay uses modern telescopes and supercomputing power to find and study atoms and molecules in interstellar space. Her astrochemistry observations are improving our understanding of star and galaxy formation, and underpin a search for signs of life beyond our own here on Earth.
After university, Chenoa came across the idea of studying chemistry in space, and it has since led her around the world. After completing a degree majoring in chemistry with a minor in mathematics in New Hampshire, she moved to New Mexico and completed more study in mathematics, physics and radio astronomy, while helping to build and test a new radio telescope, the Long Wavelength Array. She joined Curtin University as a research associate in 2011 to study high-mass star formation and then completed a PhD, using the MWA to search for molecules around stars. Now at CSIRO, she is a postdoctoral fellow commissioning and using telescopes around Australia to study the early stages of star formation.
What drew her to science?
“I was always interested in maths,” recalls Chenoa. “I’d be working on the family farm with my grandfather and he’d always challenge me with maths problems to do in my head.” Her broader interest in science was sparked in high school once she could try dedicated subjects like chemistry and physics.
Surprisingly, a career in science was never an ambition. “Growing up in a very small rural community I just didn’t have those sorts of role models – science was what you saw smart people doing on TV,” Chenoa explains. “I was familiar with farming and small business, so I thought I could funnel my maths interest into accounting and business. But I didn’t enjoy business school at all. My university roommate was studying biology and chemistry, and I realised I was spending more time helping her with her homework than doing my own! My friends eventually convinced me I could be a scientist too, so I started studying chemistry at university and absolutely loved it.”
Research with supercomputers
Chenoa uses spectroscopy, the interactions of light and matter, to look for molecules in the gas layers around stars. As molecules in space are bombarded with energy from nearby stars, they can absorb and re-emit that energy at specific frequencies based on their structure – each molecule’s energy signature is unique. Chenoa uses radio telescopes to collect signals across a range of narrow-frequency bands to build up and identify those full-spectrum energy signatures.
“That’s why we need supercomputers to do this sort of research,” explains Chenoa. “We image the sky over a lot of very narrow frequency bands, and process all of that information independently to pinpoint the energy absorptions and emissions to specific frequencies with the resolution we need to identify the molecules out there.”
“It’s only with this next generation of telescopes like MWA and ASKAP that we can view entire constellations at very high resolution, and the data volumes are massive, so supercomputing is essential to process the information. If I’d had to do my PhD research on a laptop computer, it would have taken me roughly 25 years. Now I’m using Pawsey to create over half a million images per year per project.”
Real world solutions
Chenoa is pushing the study of molecules in space to lower radio frequencies than ever before. “In the colder regions of space, much larger molecules should be more stable, and emit at these lower frequencies. It’s a very sensitive frequency range to study the chemistry of cold gases, but the emissions are not very intense or energetic, so we need very powerful telescopes like the MWA, ASKAP, and eventually the Square kilometre Array (SKA) to find them.”
Chenoa’s work is defining the relative importance of different mechanisms of star formation, and how they influence how galaxies evolve. She’s also laying the groundwork to identify ‘biotracers’ – more complex molecules like amino acids and proteins in space with the SKA.
“We already know so much about star formation and the molecules in space, but about 85 per cent of the molecules we’ve found in space are based on carbon,” notes Chenoa. “And we don’t know why. It may be because stars produce a lot of carbon, and it’s easy to make lots of molecules out of it. But we’ve only been looking in the higher frequencies – are we missing information that could be important in understanding how stars evolve, die, and spread atoms around the galaxy? Carbon may really be centrally important to life in general, but our understanding may be biased because we’ve only looked in certain ranges of the electromagnetic spectrum. Looking for atoms and molecules at lower radio frequencies could give us a more complete picture of our place in the Universe.”