Star search turns up fewer new ones

With few new stars being formed, will the twinkling lights above our heads soon disappear into the night sky?

According to Raul Jimenez, assistant professor of physics, there is now very little gas—the main component of stars—available in the galaxies, so few new ones are forming. But since stars tend to have a lifetime of 10 to 100 billion years, and our universe is a youthful 13 billion years old, we don’t need to worry that the lights above will dim anytime soon.

Published in the April 8 issue of Nature, Jimenez’s research on this topic—an extremely thorough chronicle of star formation—is the result of four-and-a-half years of study.

Previous efforts to record star formation examined only 50 or 100 galaxies. “That was very much like looking at the tip of the iceberg,” said Jimenez. “What we did was very different.” Along with colleagues from the University of Edinburgh and funding from the National Science Foundation, he created a mathematical logarithm that compressed data on galaxies from the Sloan Digital Sky Survey, a comprehensive project that is mapping celestial objects. This enabled the researchers to take into account data from nearly 100,000 galaxies.

Jimenez and his colleagues recorded the colors of stars—an indication of their age—and analyzed data on both bright and faint stars to get a complete picture of the galaxy, its “fossil record.” “We were able to be so consistent with previous findings,” said Jimenez. “[because] our methods were so robust.”

The team discovered that star formation in the universe peaked about five billion years ago, more recently than previously thought. Since that peak, the creation of new stars has dropped off considerably, since it is difficult for gas to get back into the universe once it has become part of a star. Other surveys showed an earlier date for star formation, said Jimenez, because they examined only large-mass galaxies, like the Milky Way, which formed most of their stars before galaxies with lower mass.

Jimenez said he plans to continue his research to gain even more accurate pictures of the sky above our heads.

Originally published on April 29, 2004