Exploring the Invisible Universe
November 18, 2001
by Bommy Lee, Carleton University
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
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
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
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."