Hubble Gives Scientists Look at Possible New Class of Stars : Astronomy: Despite continuing technical problems relating to a flawed mirror, the telescope is also offering researchers clues about the age of the universe.

Despite its famously flawed optics, the Hubble Space Telescope has given astronomers their first glance at what may be a new class of stars--extremely hot and blue objects stripped naked to their thermonuclear cores--it was reported Wednesday.

At the same time, other astronomers said that the Hubble telescope’s unique vantage point in space is letting them make significant progress toward one of science’s loftier goals, measuring the precise age of the universe.

The Hubble telescope has been criticized since a flaw in its focus was discovered soon after the $1.5-billion orbiting observatory was launched in 1990. The blurring is caused by a misshapen primary mirror, which collects dim light from distant stars and focuses it in a narrow beam for analysis.

“There are some things it can’t do,” said astronomer Wendy Freeman of the Carnegie Institution of Washington, “but the things that it can do, it does beautifully--and it does things we can’t do with ground-based telescopes.”

One such thing is the discovery of 15 examples of the new hot blue stars, which are in the middle of a dense cluster of stars in the Pegasus constellation.

One of the discoverers, Guido de Marchi of the University of Florence in Italy and the Space Telescope Science Institute in Baltimore, said that since the Hubble detects ultraviolet radiation it can distinguish between hot stars and the gas around them. Ultraviolet rays cannot penetrate Earth’s atmosphere, so the cluster is only a blur to ground-based telescopes, he said.

De Marchi said surface temperatures of these stars exceed 60,000 degrees Fahrenheit, more than five times as hot as the sun. Since all 15 stars are packed inside a radius of one light-year, he suspects they have cannibalized one another of their outer layers, “exposing the central nuclear engines in their cores--the very furnace responsible for their light.”

“These objects represent a totally new population of very blue stars,” he said. “They may be among the first observed stars to have been stripped.”

As de Marchi sought a brand-new kind of star, Freeman and her colleagues were looking for old favorites. Peering into a spiral galaxy in the Ursa Major constellation, they studied a pair of Cepheid variable stars and then proceeded to discover 30 new ones.

Cepheid stars, which regularly brighten and dim as if throbbing, help determine the distance of galaxies from Earth--something that cannot be done precisely using ground-based telescopes because of atmospheric distortion.

Freeman and her colleagues, Jeremy Mould and Barry Madore of the California Institute of Technology, said they plan to measure the distance to 20 galaxies over the next two years. By comparing that information with the known speed at which they are racing away from each other, they intend to estimate when these galaxies were united. That is the moment the universe was born.

Scientists generally believe that all matter, space and time once fit into an infinitely small point, which suddenly began to expand rapidly in a “big bang” to create the universe. Evidence indicates the big bang occurred anywhere from 10 billion to 20 billion years ago.