Search for star clusters turns to ‘crowdsourcing’

SALT LAKE CITY – Astronomers are looking for thousands of volunteers to scan computerized images of a neighboring galaxy in a survey that could help explain how stars are continually being formed across the universe.

The survey is exploring the Milky Way’s nearest big neighbor, the Andromeda galaxy, about 2.5 million light-years away.

Anyone can participate at The interactive website offers about 12,000 images taken by the Hubble Space Telescope, and organizers want each image to be viewed as many as 20 times.

Astronomers say it would take them too long to spotlight the star clusters on their own, and that pattern-recognition software isn’t good at picking out star clusters. They’re turning to Internet “crowdsourcing” to speed things up.

“We thought this would be a good opportunity to engage the public, and it’s been very exciting,” said Anil Seth, assistant University of Utah professor of physics and astronomy. “We’ve had more than 7,000 participants from around the world looking at 150,000 images already.”

Participants are asked to look for star clusters, which can be dated by professionals based on the light intensity of the largest – and therefore youngest – stars inside a cluster. Experts say massive stars are like rock stars: They live fast and die young.

The online project kicked off last week and will continue until summer, when a final set of Hubble photographs will bring the total number of Andromeda images to about 15,000, which will cover just a third of the spiral galaxy.

The Andromeda Project includes other scientists at the University of Washington, Adler Planetarium in Chicago, Oxford University, University of Minnesota, University of Alabama and the European Space Agency.

“You don’t need to know anything about astronomy to participate, and it’s actually pretty fun, like playing an online game,” said Cliff Johnson, a University of Washington graduate student working on the project.

Seth said finding star clusters is easy but time-consuming. He estimates half of the available images contain no star clusters at all. It took eight scientists working more than a month to identify just 600 star clusters. That’s less than a quarter of the 2,500 clusters they believe will be shown by the full set of Hubble images of Andromeda, out of about 100 million stars in all, most isolated as single specks in the images.

“Many people say, ‘I don’t know what star clusters are going to look like,’” Seth said. “But once you get started, you start seeing a pattern of clusters among individual stars.”

Participants also will see distant galaxies in the background, notable for their spiral shapes and dimmer light.

Stars can appear blue, white or reddish. Seth said that clusters with a lot of blue stars are younger in age, while white or reddish stars are older.

The clusters are thought to form from dense clouds of gas that collapse inward owing to the force of gravity before breaking up into distinct stars.

“The details of how that happens is not well understood,” Seth said.

It wasn’t until the 1920s that astronomer Edwin Hubble confirmed other galaxies exist beyond the Milky Way, each with billions of stars. Hubble observed Andromeda. It isn’t the closest galaxy, but Andromeda is the Milky Way’s closest spiral-shaped neighbor.

Andromeda wraps hundreds of billions of stars in a diameter spanning 160,000 light years across – that’s 940 million-billion miles, astronomers say. The star clusters in Andromeda are typically about 20 light years across, or 118 trillion miles.