DAVIDSON – Space is Naomi McClure-Griffiths’ frontier, and every day, she boldly goes where no man (or woman) has gone before. Because of her, our maps of the Milky Way look different than they did just a few years ago – she found an extra arm.
“That’s the thing that gets me most excited is that what I’m looking at, no one else has seen before, and there’s not a lot of fields where you can say [that],” she said after her lecture at St. Alban’s Episcopal church on Nov. 5.
The internationally recognized radio astronomer was on vacation from her position at CSIRO Astronomy and Space Science Center in Australia. Her mother, who moved to Davidson from Portland, Ore., a year and a half ago, is a member of St. Alban’s.
Although Naomi frequently gives lectures, she had never spoken in a church and never in front of her family.
David Buck, rector at St. Alban’s, said that the church community doesn’t see a conflict between faith and science.
“It’s good to hear people explain the universe that God created,” he said.
McClure-Griffiths began with Milky Way basics.
“Put a bunch of stars together in an island, and you get a galaxy,” she said.
Our galaxy contains more than 100 billion stars and has a mass that is 1,000 billion times the mass of the sun.
“The dimensions are kind of like a compact disc.”
McClure-Griffiths studies what’s in between all those stars.
“That’s where the really cool stuff is,” she said.
She said stars make up 96 percent of what’s visible in our galaxy, while the remaining 4 percent is gas and dust.
“But not like the stuff you clean off tables,” she said of the dust. “It’s more like smoke.”
The majority of the gas is hydrogen. With Parkes Observatory’s 64-meter (210-foot) telescope, among others at the facility, McClure-Griffiths uses radio waves to track hydrogen, which emits at a very low, very specific frequency.
“It has its own radio station,” she said.
Whenever the frequency shifts, it creates a Doppler effect, like when an ambulance drives by with its siren blaring. By tracking the shifts, she can follow the movement of the gas through the galaxy.
That’s how she discovered another arm of the galaxy.
“This is my spiral arm,” she said to her audience, pointing to a faint slew of stars on the slide, the furthest out spiral in the galaxy. “It’s kind of tiny, but it’s there!”
The data has been around since the 1960s and 1970s, she said, but no one saw it.
She demonstrated how her team discovered it. She played a video showing bursts and streaks of yellow light moving across a red background, looking almost like roiling lava. Toward the end of the video, a thin flash of light blazed briefly across the center.
“Did you see it?” she asked, looking up at her audience. “I’ll play it again.”
Her work earned her the 2006 Prime Minister’s Malcolm McIntosh Prize for Physical Scientist of the Year.
McClure-Griffiths explained the significance of her discovery.
“Part of our innate humanity is understanding the world around us. It hits somewhere deep,” she said. “Having one piece of the puzzle … makes us feel more complete.”
The next big question facing McClure-Griffiths is the galaxy’s serious gas problem, or rather, a lack thereof.
Stars form from molecular clouds of gas, and when they die, they take a little gas with them, she said.
“It’s like taking a small cupful from a swimming pool.”
By that logic, the galaxy should have run out of gas to form stars long before our sun was ever formed. So, the galaxy must be getting new gas, but how?
“It must be raining in our swimming pool,” she said, but “we don’t see how it’s actually getting there.”
A gas cloud entering the galaxy faces the same problem of meteorites when they come into contact with the Earth’s atmosphere – they burn up before they reach the surface, or for the gas cloud, before it reaches the disc, where most of the dust and gas particles are, where it can be used to form new stars.
The solution McClure-Griffiths is studying is the idea of a magnetic shield.
“It sounds like “Star Trek:” You have to put up a magnetic field to protect your space ship.”
The idea is that gas falling into our galaxy is surrounded by a magnetic shield that keeps it intact as a cloud long enough for it to get to the disc.
So far, her team has found two examples of the magnetic shield, and over the next decade, they’ll be searching the sky “to see whether it’s a widespread phenomenon.”
A major development that will give research a boost is the Square Kilometre Array – a one-square kilometer field of radio telescopes that will be distributed across Australia and South Africa. Construction is projected to finish at the end of the decade, and the array should be running at the beginning of the next.
To give some perspective about what that will mean for astronomers, McClure-Griffiths said, the current telescopes can “see” three times better than the ones in use 10 years ago. The SKA will “see” 100 times better, allowing for a complete map of the Milky Way and all its interstellar medium (material, gas and dust, that fills the space between stars).
“That will be exciting times for us,” she said.
Following the lecture, as McClure-Griffiths shook hands and chatted with her audience, Rev. Buck remained adamant about one point.
“I want her to name the [new] wing after a Led Zeppelin player,” he said.