The secret is in the stars

Where are you from? You might answer that it’s the place you were born or where you live now. But where is the actual stuff that makes you from?

Ultimately, that comes from the stars.

It was big picture to paint on a Sunday morning, but at Euroscience Open Forum 2012, keynote speaker Prof Jocelyn Bell Burnell eloquently charted the origins of the chemical elements that make up you and me.

“There’s a lot of mind-blowing stuff here, so if your head hurts don’t panic that is normal,” Prof Burnell told the audience at Dublin’s Convention Centre as she launched into a story that started about 13.75 billion years ago at the Big Bang.

She described the model of how space, matter, energy and time started with a huge ‘explosion’, which was really a rapid expansion from a very small size.

A few minutes after the Big Bang the conditions were just right to allow nuclear particles to stick together and there was a short window that resulted in predominantly hydrogen, plus helium and tiny amounts of ‘heavy’ hydrogen.

“Some of the hydrogen in your body comes from the Big Bang, and when you see a kid walking down the street with a helium balloon, you can say ‘there goes some of the primordial universe’,” she said.

“But that doesn’t give us life - other elements came from stars.”

In the 1960s Bell Burnell, who was born in Belfast and raised in Lurgan, helped to build an enormous radio telescope that scanned the skies and during her PhD in Cambridge she found a signal from a previously undiscovered type of star remnant called a pulsar.

She is currently a visiting professor in astrophysics at the University of Oxford, and at Esof she explained that stars start to form as particles knot together and grow.

After millions of years stars can reach temperatures and pressures where they can forge new elements including carbon, oxygen, sulphur, calcium, silicon and iron.

Then when the star explodes, the elements get released.

“Explosion is bad news for the star but good news for us because all those wonderful elements spread out into space, they fan out and become available,” she said.

“Our Sun is a late-forming star, but we needed it to be a late star because that way we had enough of the other elements like carbon and calcium and iron.”

She concluded that the death of stars led to life: “If it wasn’t for the stars we would not be here. There is stardust in your veins, we are literally, ultimately children of the stars.”

When asked about her thoughts on finding life elsewhere in the universe, Prof Bell Burnell said we need to start getting ready.

“I do suspect we are going to get signs of life elsewhere, but how well prepared are we for this? Have we thought how we will approach them? We need to start thinking about that.”

Prof Bell Burnell, who attended the entire conference, told The Irish Times why she chose the topic. “I thought it would be of interest to a wide range of people and I could include an appropriate level of science.”