Oldest Known Star Is Older Than Our Galaxy

The oldest known star had its birthday picture released today as astronomers working with NASA’s Hubble Space Telescope calculated the age of the so-called Methusaleh star. Howard Bond of Pennsylvania State University said that the ancient star with the unglamorous name of HD 140283 is 14.5 billion years old — plus or minus some 0.8 billion years.

The universe itself has an estimated age of around 13.8 billion years. Researchers in 2000 had calculated the aging star at 16 billion years, which meant that the star was born before the universe existed — clearly ridiculous. The new calculations still have a wide margin of error, but at least the math works out now to let the universe arrive first. However, Bond’s team acknowledged that this star was born very soon after the original Big Bang.

HD 140283 is actually wandering fairly close to the earth in astronomical terms. It’s only 190 light years away. According to NASA, the entire Milky Way galaxy contains around 200 billion stars, and it’s about 100,000 light years in diameter and 1,000 light years thick. As far as I’m concerned, it makes you wonder how many other stars that old or older may be out there that we simply haven’t noticed yet.

Volker Bromm, an astronomer at the University of Texas at Austin, offered some food for thought when he was interviewed by Nature. The chemical composition of the oldest known star suggests that it couldn’t have formed until the first generation of stars had already been born and then died, leaving traces of heavy elements behind. The very first stars are believed to have lived very short lives of only a few million years. Then they exploded, spewing the heavy metals found in the Methusaleh star across the universe.

This second generation was capable of a much longer life and, in fact, HD 140283 is thought to be older than our Milky Way galaxy. The Hubble astronomers postulated that the ancient star was born in an early dwarf galaxy which was torn apart by gravitational forces when the Milky Way started to form about 12 billion years ago.

What stories could the world’s oldest star tell, if only it could talk about its 13-plus billion years of adventures?

[image courtesy Hubblesite.org]