Dr. Anna Frebel calls them her “little old guys,” two stars that are almost as old as the Universe itself.

“It’s actually really difficult to fish an old star out of the sea of relatively young stars. Maybe one in 10,000 is an old star and we use the biggest telescopes in the world to find them,” Dr. Frebel told Nick VinZant during an episode of the Profoundly Pointless podcast.

An Astronomer and Stellar Archaeologist, Dr. Frebel discovered HE 1327-2326 and HE 1523-0901. HE 1523-0901 is believed to be around 13.2 billion years old, while HE 1327-2326 was born shortly after the Big Bang 13.8 billion years ago.

To find the oldest stars, Astronomers study a star’s chemical composition. The more Hydrogen and Helium a star has, the older it is.

“The Universe was made from pretty much just Hydrogen and Helium after the Big Bang. That’s how it all started. Then stars and galaxies formed and they made the heavier elements. And so with time each generation of stars made heavier and heavier elements on the periodic table. Which means, when you look for the oldest stars, we have to find the stars that have the least amount of these heavy elements in them,” said Dr. Frebel

By studying ancient stars, Astronomers can also learn more about what the early Universe was like.

“We can actually learn what the chemical composition of the early Universe was, these old stars are like time capsules,” said Dr. Frebel.

Despite their advanced age, Dr. Frebel says many of these older stars are still around and can be seen with a good telescope.

“The big stars they party too hard and blow up pretty quickly. The older stars are smaller - like 0.6 or 0.8 the mass of the sun. They burn fuel more efficiently and have expected lifetimes of 15 - 20 billion years.

To hear more of Dr. Frebel’s interview with Nick VinZant of the Profoundly Pointless podcast check out the link below. Dr. Frebel talks about protogalaxies, supernova explosions and what will happen to the sun.