Imagine sitting around a campfire, feeling the warmth on your face, and then realizing that there’s a star out there, somewhere in the vast universe, that’s even cooler than your campfire.
Sounds strange, right?
Yet that’s exactly what a team of astronomers at the University of Sydney have discovered. They’ve found the coldest star ever known to send out radio waves.
This star, or to be more accurate, an ‘ultracool brown dwarf,’ is only about 425 degrees centigrade.
To put it into perspective, that’s even cooler than your average campfire and way cooler than our Sun, which has a surface temperature of about 5600 degrees centigrade!
Now, you might be asking, “What’s an ultracool brown dwarf?”
Well, they’re not quite like the stars we’re familiar with, like our sun. Brown dwarfs are sort of the “in-betweeners” of the universe. They’re too big to be called planets but too small to become full-fledged, nuclear fusion-burning stars.
Kovi Rose, a Ph.D. student at the University of Sydney and the lead author of the study, said it’s really uncommon to find these kind of brown dwarfs producing radio emissions.
Usually, their internal workings don’t create the strong magnetic fields needed to send out radio waves that we can pick up here on Earth.
So, how is it that this particular brown dwarf is radio-active? Good question! It seems the star’s rapid spinning might be helping generate a magnetic field.
If the magnetic field spins at a different pace than the dwarf’s charged atmosphere, it can create electrical currents.
Then, the inflow of electrons towards the magnetic poles of the star, mixed with the star’s rotation, is likely causing regular bursts of radio waves.
Our radio star, officially named T8 Dwarf WISE J062309.94−045624.6 (quite a mouthful, isn’t it?), is about 37 light years away from us.
It was first spotted in 2011 by scientists at Caltech in the US. The size of this star is similar to Jupiter, but it’s a lot denser, being at least four times more massive but no more than 44 times more massive.
Rose and his team used new data from the CSIRO ASKAP telescope in Western Australia, along with observations from other telescopes in NSW and South Africa, to make this cool discovery.
Professor Tara Murphy, the head of the School of Physics at the University of Sydney, is excited about the future of their research.
She believes that as they continue to explore the radio sky, they’ll uncover more fascinating celestial objects, and possibly even learn more about potential life-harboring exoplanets around these stars.
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