LOS ANGELES — White dwarf stars are dying stars — burned-out cinders that have exhausted the hydrogen that sustains them. But scientists may soon count on these stellar flameouts to unravel the history of the Milky Way.
In a study published online Wednesday by the journal Nature, astronomer Jason Kalirai described a new technique for calculating the masses and ages of old stars based on the masses of the white dwarfs they have become. The new information will help researchers better understand the formation of Earth’s galaxy.
“If we want to assess when components of the Milky Way formed, we need the ages of the stars,” said Kalirai, who is based at the Space Telescope Science Institute in Baltimore.
Kalirai focused on white dwarfs in the Milky Way’s halo — a vast sphere, about 500,000 light-years in diameter, that envelops the galaxy’s more familiar bulge and disk. Light from the stars gave Kalirai information about their hydrogen, which he used to determine the stars’ masses.
The age of a star is directly related to its mass. The more massive a star, the more pressure at its core and the faster it burns through its hydrogen supply. Less massive stars burn more slowly.
