UPDATED 24/05/2011: I’ve added a short Q&A with Barnaby Norris.
MUCH OF THE MATTER that forms new stars and planets—and even our own bodies—is produced in the last gasps of dying, giant stars.
A thesis produced by Barnaby Norris—an astronomy student based within the University of Sydney’s School of Physics—helps answer the longstanding mystery of how these dying stars eject their matter into the galaxy.
For his work, Barnaby has been awarded the 2011 Bok Prize for the Best Honours Thesis in astronomy across all Australian universities.
“I am interested in how old stars are recycled to make a new generation of stars, planets and all the matter that makes up the universe,” said Barnaby.
Barnaby, who is now a PhD student at the Sydney Institute for Astronomy based at the University of Sydney, said he was excited to have won the Bok Prize: “This came as a great surprise. Given all the amazing work done by Australian astronomers in this field I feel really honoured to be selected.”
The Bok Prize is awarded annually by the Astronomical Society of Australia to recognise outstanding research in astronomy by an honours student at an Australian university.
It was established to honour Dr Bart Jan Bok, the Director of Mount Stromlo Observatory from 1957 to 1966. Dr Bok energetically promoted the undergraduate and graduate study of astronomy in Australia and set up the Graduate School of Astronomy at the Australian National University.
The prize consists of the Bok Medal together with an award of $500. The recipient is invited to present a paper on their research at the Annual Scientific Meeting of the Astronomical Society of Australia, where the prize will be presented.
SpaceInfo spoke with Barnaby Norris, and asked him about his research:
Can you give us more detail about your research into how stars are ‘recycled’?
I’m studying stars that undergo big pulsations over a year or so, during which they expel a lot of material in the form of a ‘stellar wind’.
Along with supernovae (exploding stars), the gas and dust expelled by these stars is the raw material that goes on to form the next generation of stars. But there has been a big mystery as to how exactly this loss of mass occurs.
It’s known that the mass loss is related to a shell of dust that forms around the star. But it’s incredibly hard to directly observe the dust shells—you’re trying to see this relatively faint detail around a star that is perhaps only 40 milli-arcseconds across (less than a millionth the width of the full Moon).
The research I did was one of the first times these shells of dust have been directly imaged. This led to measurements of the size of the shells and the size of the dust particles that make them up, which can be used in computer models to better understand the mass-loss process.
What observations did you do, and what astronomical facilities did you use?
Due to the tiny angular size and high contrast involved, you can’t see the dust shells using regular astronomical imaging—it’s like standing in Sydney looking at a streetlight in Perth, and trying to figure out the species of moth flying around it!
I used a new technique based on a type of interferometry called aperture masking, combined with measurement of the polarisation of the light.
Aperture masking effectively turns a large telescope into lots of smaller telescopes. Combining the images helps you to see fine detail.
The observations were all done using the 8-metre telescope at the Very Large Telescope in Chile. I carried out some of the observations last year, and I also used some data taken by my supervisor and others the previous year.
My supervisors—Peter Tuthill (University of Sydney) and Michael Ireland (Macquarie University)—really pioneered the techniques I used in this study, and contributed immensely to the project.
Bart Bok, after whom the prize is named, was an astronomer who researched dark interstellar clouds (‘Bok globules’) that are involved in star birth and rebirth. Is it a nice touch that your work is in a closely related field?
Yes that is a nice touch. The whole cyclical nature of stellar evolution, from the death of old stars to the birth of new ones, such as in Bok globules, is really fascinating to me.
Finally, what got you into astronomy, and where would you like to go in this field?
I’ve always been fascinated by astronomy, and science in general, but I also love good nerdy stuff like building gadgets and writing computer programs. I could never be a theorist. I love the type of astronomy where you can get your hands dirty—bolt together an instrument in a lab, write some code, and then use it to find out something new!
Adapted from information issued by the University of Sydney. Portrait image courtesy University of Sydney. Hubble image courtesy NASA, ESA, R. O’Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Centre), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA).
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