Why do stars twinkle? │ 5-Minute Science You Never Knew with Dominic Bowman

ZOEY

Hi, hello everyone, welcome to ‘5-minute Science You Never Knew.’

Today we are honoured to have our guest Dominic to talk about his subject.

So, here I'd like to give the stage to Dominic already, because I'm sure that some of us haven't heard about this word in English. Please, Dominic.

DOMINIC

Thanks very much for having me.

So yes, that word is asteroseismology, and as an astronomer what that word means to me is learning about the interiors of stars from their pulsations. Asteroseismology is Greek for seismology of the stars.

When you're outside at night and you possibly see hundreds or thousands of stars, in astronomy if a star changes its brightness, we call it a variable star. You might be familiar with this because you see stars twinkle in the night sky. Mostly it's because of the starlight passing through the Earth's atmosphere and getting knocked around. It's very turbulent in the Earth's atmosphere.

But stars can also be variable stars because of pulsations. The interior of stars is quite a noisy place. There are large energetic reactions going on that generate the energy and heat to support the star. But these reactions and the conditions inside a star can also excite pulsations.

Pulsations can include sound waves, that's how we communicate vocally to each other. But these waves propagate, they travel through the star from the surface to the centre and back again. They cause the surface of the star to shimmer and twinkle. And so, the twinkling of the surface of the star allows asteroseismologists like myself to learn what's really going on in the deep interior.

ZOEY

Wow, that's very impressive. Could you give us a little bit more detail about your research? What have you been doing?

DOMINIC

Absolutely, yes. Well, as a researcher at the University, KU Leuven, in Belgium, I use space telescopes to understand the pulsations in some of the most massive stars in our Universe. Stars known as blue supergiants. These blue supergiant stars are important metal factories in the Universe, because they produce all the elements on the periodic table heavier than helium when they explode as a supernova at the end of their lives and form a black hole or a neutron star.

But blue supergiants have been quite difficult to study until very recently, because they don't live very long. They only live for about a few million years, which sounds like a long time to us, but stars like our Sun live for 10 billion years, and that's much much longer. This makes blue supergiants quite rare, they're almost like the rock-and-roll stars of all the stars in the night sky because they live fast and die young.

But recently using space telescopes from NASA, we've detected pulsations in hundreds of blue supergiants. This is research that was led by myself at KU Leuven and funded by the European Research Council.

It's allowed us for the very first time to test the interiors of blue supergiants, to detect how much metal the stars are really making and how it's transported within the star itself. It's a really exciting prospect because these stars are progenitors of those supernova explosions, and we really wanted to figure out what's going on.

ZOEY

Wow, so if our audience would like to take away one more message from what you are studying, what would it be?

DOMINIC

I would just remember that the next time you're outside and you see a star twinkle or

shimmer, that star you're seeing, although it's very very far away, it might also be one of these pulsating stars that we're learning a lot about.

ZOEY

Well, I shall remember that. Thank you so much for your time Dominic. I hope to speak to you again soon.

DOMINIC

Thank you very much for having me.

ZOEY

Bye, thank you!