Bacon and Eggheads

Dr. Christine Wilson, Professor in the Department of Physics and Astronomy at McMaster University, illuminated the possibilities of exploring the invisible universe at a breakfast hosted by The Partnership Group for Science and Engineering on Oct. 30, 2001.

"If you talk about something being visible, it means that you can see it in light," she says. "Our eyes are sensitive to a fairly small range of wavelengths of light from about roughly 400 nanometres to 700 nanometres. But the universe emits energy at wavelengths both much shorter and much longer than the wavelengths of visible light, and that's what I call the invisible universe."

Wilson studies the invisible universe to find clues about how stars are formed.

Star formation is the process by which a gas region of low density and low temperature becomes a region of gas that is of much higher density, and large and hot enough in the centre to start burning the hydrogen within it to form helium.

Wilson's research focuses specifically on using radio waves, which are very long wavelengths in the invisible spectrum. She says this is important because, at these wavelengths, the invisible universe reveals aspects of star formation that would not be evident by looking at only the visible universe.

To illustrate, she gives us the following example.

Dust is mixed in with the molecules that form gas clouds that become stars. The dust particles are significantly smaller than the ones we find on earth, only about a micron in size. These dust particles obstruct our view of the gas cloud, making it difficult to see it.

Wilson compares this phenomenon to a fire where smoke builds up and blocks our view of what's on the other side.

"You can't see what's behind [the gas clouds] because of the dust and it also means you can't see what's inside them because of the dust, you only see the outer surface and then you're blocked," she says.

However, this problem can be overcome if we study the invisible wavelengths.

"By looking at the radio wavelengths, you actually can see right through [the dust particles] so you can study what's going on in the middle as well as in the outer part of whatever you're interested in," says Wilson.

She illustrates this through her ongoing research of the Antennae, two colliding galaxies about 60 million light-years away. Since it is the closest example of colliding galaxies to our galaxy, the most detailed information can be collected.

"I'm working on the problem of trying to understand why very bright massive star clusters have formed in the Antennae. I'm going to continue working with the data that I have for the Antennae, and we're hoping to search for more star clusters in a couple of other slightly more distant interacting galaxies using the Hubble space telescope," says Wilson.

Wilson is currently the Canadian Project Scientist for the Atacama Large Millimeter Array (ALMA). ALMA is a partnership between North America and Europe. The project will consist of 64 radio telescopes, each 12 metres in diameter, and will be built in northern Chile, an ideal site because of its dry climate and high elevation above the atmosphere.

"Japan is also interested in joining as well to form a third partner but they may join a bit later, because of funding constraints in their country," says Wilson.

ALMA will cost about $550 million US, half of which will be funded by Europe. The U.S. will be contributing just over $250 million and it is proposed that Canada put in $20 million.

"A colleague of mine said it's amazing that Canadian astronomy does as well as it does given our relatively low amount of funding, and I think part of that is that we use it very efficiently, and we work together in teams both inside Canada and with international partners. But if we're going to keep up this level of expertise and reputation, I think we are going to need some more funding for things like ALMA," says Wilson.

Wilson is confident that Canadian astronomers will continue to play a leading role in the international community.

"Astronomy in Canada is by several measures, our best internationally known science. Some studies have ranked Canadian astronomy in the top three in the world in research, with the U.K. and U.S. So astronomy in Canada is very well known and highly respected internationally."