New Canadian-led research that uses NASA's Hubble telescope to examine the age of elderly stars is shedding new light on how the Milky Way was "put together."
The study is being conducted by a team of 13 researchers in Canada, the United States and Australia to learn when exactly the centre of our galaxy developed compared to the rest of the Milky Way.
"The main idea is to really determine what the archaeology of our own galaxy is," said Harvey B. Richer, a professor of astronomy at the University of British Columbia who is the study's primary investigator. "How did our galaxy form?"
For their research, Richer and his colleagues have won the right to have NASA's Hubble space telescope take photographs of a cluster of stars named 47 Tucanae. "Tuc," as its informally called, is located about 11,000 light-years away and sits in the constellation of Tucana, which is visible from the southern hemisphere.
It's made up of the same type of stars as in the galaxy's central "bulge," Richer said. By determining its age, the researchers hope to settle a dispute over whether the galaxy formed from the inside out, or from the outside in.
To do that, the Hubble telescope is snapping photographs of Tuc during a portion of its rotations around the Earth this year.
Technicians then edit the images for distortions caused by cosmic rays. Richer downloads them on to his computer, and the research team sets about analyzing them.
They're particularly interested in a type of star known as a white dwarf.
"It's like a hot rock that has been heated up for a long time and now there's no fuel left," Richer said. "These things cool in a very predictable way, so this is like an incredible cosmic clock where the temperature tells you how old it is."
Richer said he and his colleagues have helped to pioneer the white dwarf technique, which he likens to radiocarbon dating in archaeology. They have used it to help determine how old two other components of the Milky Way are.
According to their calculations the halo, or the faint cloud of stars around the galaxy, is about 12 billion years old. They estimate that the spiral-shaped ring around the bulge to be about 4 billion years younger.
Now they're hoping to use the white dwarf technique to determine the age of the bulge, or the galaxy's centre.
"The results are extremely preliminary," Richer cautions. "But it looks as though the halo and the bulge formed rather simultaneously, with the disc forming quite a bit later."
The researchers have collected about 80 per cent of the data they need, and Richer says they hope to publish more definite conclusions by December.
Aside from determining how galaxies in the universe were formed, their work could also shed light on the origins of life.
"These are some of the first stars formed in the universe," Richer said. "So if we find planets around stars in this cluster, that tells us that planets formed early in the history of the universe and that there was perhaps an early rise to life in the universe."
Source: CTV News