Understanding our home: the Milky Way

The far reaches of the Universe hold many mysteries—but there’s a lot we still don’t understand about our own backyard, the Milky Way galaxy within which our Solar System sits. How did it form, and how has it grown? How are new stars born within our galaxy, and how do old ones die? These are some of the questions about our galaxy that Australian astronomers are working to answer.

Our gas-guzzling galaxy

NAOMI MCCLURE-GRIFFITHS WITH THE PARKES RADIO TELESCOPE. CREDIT: DAVID MCCLENAGHAN © 2011 CSIRO.
NAOMI MCCLURE-GRIFFITHS WITH THE PARKES RADIO TELESCOPE. CREDIT: DAVID MCCLENAGHAN © 2011 CSIRO.

“There’s a lot we still don’t know about our Milky Way galaxy,” says Naomi McClure-Griffiths of the CSIRO Astronomy and Space Science. “It’s the old can’t-see-the-forest-for-the-trees problem—we have a hard time seeing its structure from the inside.”

Since 2004, Naomi has headed the Galactic All Sky Survey (GASS), the most sensitive survey of the galaxy’s hydrogen gas visible from the Southern Hemisphere. Using CSIRO’s Parkes radio telescope, GASS is investigating how different parts of the galaxy interact, where stars are being formed, what happens when they die, and how they cause new stars to be born.

“Our galaxy is basically a big machine that’s producing stars from gas,” says Naomi. “How that works is a question that dominates not just galactic astronomy, but astronomy in general.”

The survey half of the project is complete and now the analysis has begun, with six papers already published. One thing the team is hoping to determine is whether the bits and pieces of gas floating around the galaxy are the fresh ‘food’ the galaxy needs to make new stars. Does this gas come from outside or inside? “We’re finding that it’s both,” says Naomi. “But the galaxy particularly needs fresh stuff from outside, and we think that comes partly from small galaxies it has consumed.”

The Parkes telescope, which is now fitted with a receiver to observe multiple parts of the sky at once, is vital to this study, says Naomi. “The multibeam instrument has made Parkes seven times better and completely revolutionised the field,” she says. “If the multibeam didn’t exist, work I finished years ago would still be incomplete today.”

PHOTO: NAOMI MCCLURE-GRIFFITHS WITH THE PARKES RADIO TELESCOPE. CREDIT: DAVID MCCLENAGHAN © 2011 CSIRO.

CSIRO Astronomy and Space Science Dr Naomi McClure-Griffiths, Tel: +61 (2) 9372 4321, naomi.mcclure-griffiths@csiro.au, www.atnf.csiro.au/research/GASS/

Also in this section:

Galactic archaeology— digging into the Milky Way’s past
Profiling and fingerprinting the stars
Stellar immigration