Podcaster: Richard Drumm
Title: Space Scoop: Is the Sun Really a Giant Pokémon?
Organization:365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1134/
Description: Space scoop, news for children
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 365 Days of Astronomy. 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: Is the Sun Really a Giant Pokémon?
Over the last few weeks Pokémon Go has taken the world by storm. Visit the beach and you’ll see dozens of people battling to catch water-type Pokémon like Magikarp or Krabby.
Take a walk in the countryside and you’ll find yourself surrounded by grass-type Caterpies.
But what type of Pokémon would you find in space?
Maybe you’d find Solgaleo, the legendary psychic-type Sun Pokémon, from the “Pokémon Sun” game that’s set to be released in November 2016.
Hmmm. Maybe.
While the Sun is obviously not a Pokémon, it actually has a lot in common with an electric-type Pokémon called Magneton.
According to the Pokémon story, magnetons frequently appear whenever sunspots flare up. ‘Discharge’ and ‘Zap Cannon’ are two of Magneton’s most powerful attacks.
In the real world, as opposed to the Pokémon world, the Sun really can create powerful solar storms capable of knocking out communication satellites and damaging electrical power systems here on Earth!
These storms are caused by magnetic fields on the Sun. A magnet (like those you can stick to your refrigerator) creates an invisible force field all around it, called a magnetic field.
So the Sun acts like a magnet. But how the Sun, and stars like the Sun, create their magnetic fields is a bit of a puzzle.
The inside of a star like our Sun is made of layers:
– All the way in the center of the star is the core. This part experiences the greatest heat and pressure from the gravity of all the stellar matter above it. Here is where the energy of the star comes from as hydrogen nuclei are fused into helium nuclei.
– Just above the core, there’s the radiative zone where the star’s energy moves inexorably outwards. The gamma ray photons wander randomly, taking on average over 170,000 years to traverse this zone. The heat also moves by simple thermal conduction through the radiative zone.
– Then farther out there’s the convective zone where the energy circulates up and down, like convection currents in a pot of water coming to a boil.
We must also consider stars that aren’t as massive as our Sun, particularly the lower mass stars called red dwarves or M-dwarves that can have up to 35% of the mass that our Sun has.
They have only 1 layer! The whole star is one giant convective zone!
The center of the M-dwarf, where the fusion happens, is constantly recycled from the whole star, not just the core. As a result there is more hydrogen fuel to draw from and the lower mass means that the rate of fusion is much less.
Thus M-dwarves have lots of fuel and consume it very slowly, lasting trillions of years, where our Sun will last maybe 10 billion years.
Many scientists have believed that the magnetic fields of Sun-like stars are produced in the area where the radiative & convective layers meet. This narrow zone is called the tachocline.
However, M-dwarves don’t have these layers, as you can see in today’s album artwork. The M-dwarf is the red star in the upper right hand side while the Sun-like star is in the lower left corner.
You can see in the graphic that the Sun-like star has several layers while the red dwarf has but one.
Yet a new study of 4 red dwarf stars has just found that they do have magnetic fields similar to stars like the Sun even though they don’t have the layers or the tachocline border area!
Two astronomers, Nick Wright from the University of Keele in Staffordshire in the UK, and Jeremy Drake from the Harvard-Smithsonian Center for Astrophysics in Massachusetts in the US have published that important new study.
It suggests that the whole convective zone, with its churning & boiling material is the source of the magnetic fields since both Sun-like stars and M-dwarves have significant convective zones.
It looks like our theory for understanding the source of these magnetic fields needs to be re-examined!
Hey, Here’s a Cool Fact!
We measure how powerful a star’s magnetic field is by looking at the amount of X-rays it gives off. More X-rays equals a faster stellar rotation, which in its turn equals a more powerful magnetic field!
Observations spanning several decades have definitely established the connection between X-ray output and stellar rotation and between the rotation rate and the magnetic field strength.
Thus X-ray emission is a reliable proxy for magnetic activity and that is why we can detect the magnetic activity of dim little stars that we can’t even see with our naked eyes! We use the Chandra X-ray Space Telescope instead!
You know, the red dwarf kinda reminds me of a Poké ball. It has a friendly monster inside it too!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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