Supernovae : Kyle Koeller guest post


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Supernovae are one of the most powerful explosions in the universe. They produce explosions millions of times larger than the most massive volcano eruption in Earth’s history. Supernovae can even be seen from Earth; in 1054 AD a supernova shone so brightly that it was visible during the day!

 Hubble image of the Crab nebula; the remnant of the 1054 supernova

Type Ia or Type II?

Broadly, there are two types of supernovae: Type Ia and Type II. Type I form when a star accumulates matter from a nearby neighboring star until it has a runaway nuclear reaction and explodes.

A Type II supernova occurs when a star runs out of nuclear fuel and collapses under its own gravity. Type II is what most people picture when they think about a supernova. Hydrogen fuses into carbon under the immense pressure at a star’s center. This nuclear reaction fights against gravity to keep the star up and alive. So, when you look at our Sun, you are watching nuclear fusion and gravity in a very delicate balance. Type II supernovae occur in stars 8-15 times the size of the Sun when the fuel for nuclear fusion runs out. When a star starts to collapse it takes all of a couple of seconds for it to collapse down to smaller than an atom. The star collapses down to a minuscule point in space and then immediately releases all of its contents out into space in the blink of an eye. The materials include gold, iron, nickel, and so forth. All the heavy elements inside your body were created inside the dying guts of a supernova!

What's in a star?


The way Astronomers can know the contents of such supernovae is by looking at the spectra of their light. For example, the image below shows the spectrum of the Sun; those spikes in the wavelength tell us which elements are present. This indicates that Helium is present inside the Sun. Now image multiple of these on top of each other at all different wavelengths and peaks at those wavelengths. If you were to look at our star, The Sun, you would see mostly Hydrogen and some Helium, and that is about it. This is because our star is only halfway through its life cycle, 4.5 billion years, and has not had enough time to produce a lot of heavier elements within its core. The sun will live for another five billion years before its outer layers expand and incinerate the four inner rocky planets and leaves behind a red dwarf star.


 Image from a fab NASA worksheet - click through to see the original source

What's in a supernova?

Just as we could see the elements in the spectrum of the Sun, we can see the emission and absorption lines for a supernova! You can see how different they are in the diagram below...

 Image from a rather splendid UNI document - click through to see the original source

A note from Becky: I based my 'supernova' necklace on the spectrum of a typical Type Ia supernova - each line represents the wavelength of an absorption or emission feature. Cool, huh? From left to right the lines are: FeIII, CaII, SiII, FeII, SiII (yep, it appears more than once!), OI, MgII, CaII. Click on the image below to make it yours!



About the author

Hello! My name is Kyle Koeller and I go to Ball State University as an undergraduate. I am currently working towards getting my Astronomy Major with minors in Math and Computer Science. I am also working on research with a professor on binary star systems and analyzing the light curve produced when they orbit each other. After I graduate and get my M.S. I want to get a Masters from the University of Arizona and get my Ph.D. somewhere else.

You can keep up-to-date with Kyle on Instagram - why not go and say hi!