Though they’re not privy to cosmetic surgery or the perks of science’s best tools, even stars have to worry about aging these days — but there is some hope.
Through the work of Penn State Professor of Astronomy and Astrophysics Steinn Sigurdsson with the European Research Council’s Cosmic-Lab project, the team observed that globular clusters contain an internal clock. Better known as the presence and location of “blue stragglers,” these internal clocks help indicate how close a cluster is to collapsing in on itself.
Inside these clusters of stars are blue stragglers, which form when two stars collide. Blue stragglers have a larger mass and are brighter than the other stars in the cluster — and therefore more easily observed by astronomers, Sigurdsson said.
If the blue stragglers are concentrated in the center of the cluster, then the cluster is closer to collapsing in on itself. But, if the blue stragglers are more toward the outside of the cluster, then it has more time before the cluster will collapse in on itself, Sigurdsson said.
While the number of blue stragglers in a cluster varies, as they concentrate there will be more of them, he said.
The project, Cosmic-Lab, is “designed for studying the impact of dynamical evolution of star clusters on the evolution of individual stars,” Francesco Ferraro, professor of astronomy at the University of Bologna and principal investigator of the project, said via email.
“We called the project ‘Cosmic-Lab’ since it uses the star clusters as cosmic laboratories,” Ferraro sad.
The clusters are like laboratories because they contain similar stars, formed around the same time, Sigurdsson, a co-author of the study, said. A globular cluster is a collection of between 100,000 and a few million stars, he added.
The team discovered that the distribution of blue stragglers in a globular cluster affects how quickly or slowly a cluster’s internal clock is moving, he said. The team observed about 20 globular clusters, Sigurdsson said.
To view the blue stragglers in the center of globular clusters, the team used the Hubble Space Telescope, while other ground-based telescopes were used to view the outer limits of the clusters, he said.
“This discovery finally opened the possibility of recognizing how much a given cluster has evolved since its birth,” said Barbara Lanzoni, researcher at the University of Bologna and a co-author of the study. “In turn, this allows us to more precisely characterize and reconstruct the history of star clusters.”
