What's the difference between a dwarf and red giant? Just listen to the starlight.
The light of stars tells their stories.
Scientists have found a way to transform light from stars into sound — then they use the sound to understand them.
The sounds range from something like the sizzle of bacon to that uncomfortable noise that happens when you mistakenly switch to AM radio.
But the coolest part is what they can tell us about the stars themselves. Listen here; it's oddly soothing:
What the heck?
Yeah, I know. From what I can tell, it's the frequency of flickering starlight detected by the mighty Kepler telescope that is transformed into sound.
In an interview with The Telegraph, Dr. Bill Chaplin, an asteroseismologist (or star scientist, roughly) at Birmingham University, explains it for us normals by way of musical metaphor:
"Essentially stars resonate like a huge musical instrument. Stars make sounds naturally but we can't hear this as it is has to travel through space.
Like a musical instrument, stars are not uniformly solid all the way to their core, so the sound gets trapped inside the outer layers and oscillates around inside.
This makes the star vibrate causing it to expand and contract. We can detect this visually because the star gets brighter and dimmer and so we can reconstruct the sounds produced from these vibrations."
Turns out these vibrations can tell us some stuff about stars, like their size.
Stars come in all sorts of sizes, but let's talk about the "sounds" of three common ones and how they relate.
A dwarf star is a star that's roughly the size of our sun.
(I'll just let that sink in a bit, there, as you digest that in comparison to the other star sizes above.)
Anyway, dwarf stars spin faster than large stars because they are smaller. When light from these stars are turned into sound, the lack of "hiss" means the surface area is very small (thus, very little granulation). But because it spins so fast, the sunspots will make the light more irregular — meaning the tone is inconsistent. Go to 1:10 in the video to see what I mean; you can very easily identify how the low tone changes gradually.
Following this pattern, larger sized sub-giants have less of that irregular sunspot flickering because they spin at a slower rate. So the tone is less all over the place, but they have more of that hiss because they're bigger. You can hear this at 1:28 in the video.
Big, ol' red giants are crazy loud because they have tons of granulation and spin very slowly. This results in the maddening static sound you can hear at 1:45.
The coolest part? These sounds also give us insights into other worlds! (Maybe.)
For the brightest stars, our space buddy Kepler can detect when planets cross over the stars based on how the light is disrupted. And the measurements can be very, very accurate — which can give us some hints toward exploring planets that may support habitable life.