科学美国人60秒:Nearby Star Came In with the Bang

There's an old-timer in the neighborhood, and it's got a story to tell. A new study of a relatively nearby old star shows that it’s almost as old as the big bang itself.

The star HD 140283 lies about 190 light-years away in the constellation Libra. Astronomers have long known that it's ancient, because it contains mostly hydrogen and helium—which were present at the dawn of the universe—and few of the heavy elements that were forged later in stellar furnaces.

With the Hubble Space Telescope, researchers have now pinned down the distance to HD 140283, which allowed them to determine how bright the star is. Along with the chemical composition of the star, the newly derived stellar properties allowed for a new age estimate.

The study of HD 140283, in the Astrophysical Journal Letters [Howard E. Bond et al., HD 140283: A Star in the Solar Neighborhood That Formed Shortly after the Big Bang], found that the star is 14.46 billion years old. But the entire universe, as you may have heard, is only 13.77 billion years old. The two age estimates aren't actually in conflict, because there’s always some uncertainty. The full age estimate is thus 14.46 billion years plus or minus 800 million years. Put your money on the minus.

—John Matson