Scoping out Star Stuff

For a guy who's examining a tiny piece of the night sky, Tyler Foster sure is covering a lot of territory-about 30,000 light years. Working on his PhD thesis in astrophysics, Foster is attached to a National Research Council project called the Canadian Galactic Plane Survey. And together with his supervisor, Dr. David Routledge, they're making new discoveries all the time.

"The project is to map out our portion of the Milky Way Galaxy and find out what the interstellar medium is made of," says Foster. "The question is: what's between the stars? What is out there that allows stars to form?"

Circles mark areas surveyed with the 26-metre radio telescope at the Dominion Radio Astrophysical Observatory. The squares represent areas imaged at the University of Alberta's Devon Astronomical Observatory. The large cloud at the top of the image is possibly the largest ionized hydrogen region in the galaxy. Other areas under study are labeled.

Trained as an optical astronomer, Foster has added radio astronomy to his repertoire, allowing him to study not only stars but also the stuff that lies between them. "There is an old saying that optical astronomers see the stars and that radio astronomers see the stuff between them and I get the best of both worlds."

From his desk in the University of Alberta physics building, Foster punches keys on his computer to point Canada's largest telescope-a 26-metre radio telescope at the Dominion Radio Astrophysical Observatory just outside of Penticton, B.C.-to the deep-space objects he's interested in. Once he has captured the radio signal of an object that draws his attention, Foster makes the 45-minute drive from campus to the U of A's 20-inch reflector telescope at its observatory near Devon, to make a visual inspection of the object.

"We are looking out two-thirds of the way into our galaxy, and to do that optically is rare," says Foster. "When we began this, there were a lot of skeptics out there who said, 'you won't be able to see anything.'" But they're seeing plenty. "Most of these things, no one has ever seen before," he says. "And that is the beauty of it. We are constantly making discoveries out there. Sometimes it gets out of hand." The experience can be emotionally rewarding. In his seminal series of books on sky watching, Robert Burnham remarked that it's fine to admire an artistic masterpiece, but the sky is nature's art gallery, with its finest works on display for all to observe and none to possess.

"Is it humbling?" Foster asks. "Oh, you can't even put it into words. Every time I see something new I feel like asking, 'why me?' Why am I the first person to see this? It's fantastic." The patch of the night sky Foster finds so intriguing lies about 10 degrees north of the star Deneb, which marks the tail in the constellation Cygnus, the swan. Looking at the sky, if you fully extend your arms and join your thumbs side by side, you could block out the entire region Foster is surveying. Yet it turns out this largely unexplored corner of the Milky Way could contain the largest known ionized hydrogen region in the galaxy.

What Foster examines, specifically, are regions of ionized hydrogen-like the Orion nebula-which are the birth places of stars, and super nova remnants, such as the Crab nebula in Taurus. In astronomical terms, super nova remnants don't last very long. Chinese astronomers observed a super nova 1,000 years ago that is now known as the Crab Nebula.

They explode so violently that they dilute themselves after about 25,000 years," he says. The super nova remnant Foster is studying "is probably only 12,000 years old."

Foster is studying ionized hydrogen regions. The Orion Nebula, above, is a prime example of such sites and is an active nursery of newborn stars. The object is located about 1,600 light years from Earth-right in our own backyard, compared to other deep-space regions studied at the Devon observatory.

Ionized hydrogen regions, on the other hand, last "quite a bit longer." Initially they are cold clouds of hydrogen, until a star forms inside one of them, emitting ultraviolet radiation and exciting the hydrogen gas surrounding it. "These are the birthplaces of stars," Foster said.

"One of the things we can do out at Devon-and this pulls it all together for me-is use the scope to detect the stars that have formed within these clouds as well."

But what really intrigues Foster is the previously undetected background to all this. His work has uncovered a vast cloud of dust and gas never before seen. "That is part of what the thesis is about: what is that background-is it related to those objects? Is it in front? Is it behind? No one knows. This is unexploredŠThe question is, how is that junk interacting with the objects we see there?"

Ultimately, understanding what outer space is made of will help us understand our own origins, and our place in the universe, says Foster. All the elements on Earth, and all the elements in our bodies, he says, come from super nova remnants.

"We are all made of star stuff," he says. "Understanding the interstellar medium and what it is made of, because it is enriched by super nova remnants, is relevant because it is what we are made of. It is a question of origins, and here are the answers, staring at us from the sky."