Podcaster: Richard Drumm
Title: UNAWE Space Scoop – Tune in to the Supernova Radio!
Organization: 365 Days Of Astronomy
Link : http://365daysofastronomy.org/ ; https://www.spacescoop.org/en/scoops/2313/tune-in-to-the-supernova-radio/
Description: Space scoop, news for children.
For the first time ever, astronomers have detected radio waves coming from a Type Ia supernova! This ‘special radio broadcast’ might carry clues to solve a longtime puzzle – how white dwarfs really explode!
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Today’s story is…Tune in to the Supernova Radio!
June 8, 2023
For the first time ever, astronomers have detected radio waves coming from a Type Ia supernova!
This ‘special radio broadcast’ might carry clues to solve a longtime puzzle – how white dwarfs really explode!
Type Ia supernovae are exploding white dwarfs that have stripped material off of a binary companion.
Single white dwarfs, ones without a binary companion, rarely explode.
They’d have to accrete material from somewhere.
With no binary companion it’s hard to imagine where the gas would come from.
So Type 1a supernovae basically always happen in binary systems.
Astronomers think that in the presence of a nearby companion star, the white dwarf, with its super strong gravity, pulls material from the companion star’s outer layers, a process called ‘accretion’.
The dwarf pulls the gas from its companion when it’s closest to it in its elliptical orbit.
Then it orbits a bit farther away and the accretion stops for a time.
Rinse & repeat for a few billion years…
The accreted material is usually made up of Hydrogen, but for older companion stars that have lost their outer Hydrogen layer, it can also be Helium.
This is called a Helium star, which is rather rare!
The outer Hydrogen layer has been pushed away by the terrific radiation pressure of the Helium core.
The white dwarf accretion continues until it reaches a very specific mass, where it can eat no more and it explodes.
Sounds like me at Thanksgiving dinner!
That ‘very specific mass’ is 1.44 times our Sun’s mass and is called the Chandrasekhar Limit.
That limit is when the quantum mechanical electron degeneracy pressure of the core can no longer support the outer parts of the white dwarf and the whole white dwarf is literally obliterated!
It was calculated by Subrahmanian Chandrasekhar in 1930 while he was on a steam ship traveling from India to England to attend the University of Cambridge.
However, not all the material from the companion star falls onto the white dwarf during accretion.
Some of it will be pushed away from the companion star by its fierce solar wind and will form a cloud around the whole binary system.
White dwarves are messy eaters, so to speak.
I know a couple dogs that’re like that, kibble goes everywhere!
Anyway…
When the white dwarf reaches the Chandrasekhar Limit and explodes, the shock waves from the supernova explosion pass through this cloud.
Kinda like some sort of cosmic traffic jam!
This will give the surrounding material a lot of energy that it releases as strong radio waves.
Astronomers had been looking for this for decades and had yet to see radio waves coming from such an explosion, until now!
An international team of researchers studied in detail a Type Ia supernova that exploded in 2020.
That supernova is called SN 2020eyj.
And Jackpot!
The astronomers had successfully detected supernova radio emission for the very first time!
They studied the spectrum of the radio signal and found that the surrounding materials, which had been shed off from the companion star, were mainly made up of Helium.
That’s when they discovered that the companion was a Helium star!
Jackpot again!
Astronomers are now looking to detect radio waves coming from more Type Ia supernovae, to help them understand these explosions better.
Hey, here’s a cool fact!
Did you know?
The peak brightness of a Type Ia supernova is so strong and steady that astronomers use them as ‘standard candles’ to calculate distances in the Universe and the rate at which our Universe expands!
This’s because of the Chandrasekhar Limit of 1.44 solar mass.
That mass limit is an upper and lower limit to the brightness of the explosion .
It’s like the supernovae are always shining with the exact same amount of light, like the old standard 100 watt light bulb.
If you see a 100 watt light and measure how bright it looks from where you are, you can calculate how far away it is from you.
This is how we know how big our galaxy is and how far away the galaxies all around us are.
This is one of the keys to understanding the cosmos!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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