The current “supernova of the century”, Supernova 2014J in M82 in now at its peak brightness, but the weather here in the south west of England is so dire that cloud cover is conspiring to thwart almost any obsevations of the object.
Fortunately, a few nights ago a rare clearing of the skies gave me the chance to train my telescope on the heavens, giving me a fine view of the exploding star. Judging by the weather, that’ll be the first and last time I see it.
One of the truly awesome things about looking at a supernova through a telescope is realising that you’re actually looking at a star in a different galaxy. When an amateur astronomer trains a telescope at a galaxy the stars are usually too faint to be resolved as individual objects, giving the galaxy the appearance of a fuzzy blur. A supernova however can be so bright during its short explosive lifetime of several weeks that it outshines the rest of the stars in the galaxy put together.
Supernovae can be created in one of two ways:
- A normal star burns due to the fact that the huge mass of matter in the star collapses in on itself, creating a nuclear furnace at the star’s core as atoms fuse together under the pressure. The heat generated by this nuclear furnace acts against the star’s gravity and holds the star in equilibrium, preventing it’s total collapse. When massive stars run out of fuel it cools down and there is no more internal pressure from the nuclear furnace within the star to sustain the star against its own gravity, allowing it to collapse under its own weight. The outer layers of the star fall inwards creating a core that’s so super-dense that it then rebounds in a massive explosion.
- In some supernovae a star that has already collapsed into a compressed cool core, but that is too small to trigger an explosion from the material in the compressed core (Such stars are known as a white dwarves), can acquire extra matter from a companion star when the two stars are orbiting each other and are thus under each other’s gravitational influence, so that the white dwarf reachs sufficient mass to trigger a thermonuclear explosion. Supernova 2014J is this is the type of supernova.
Perhaps the most fascinating thing about supernovae, in my view, is that they are the source of all of the elements in the universe that are heavier than iron. All of the atoms of all of those elements started their lives in the the heart of supernovae.
Lighter elements are created in the cores of more pedestrian stars, in which atoms of hydrogen and helium (the only elements that were created at the beginning of the universe) fused together under the intense heat and pressure. Normal stars however just don’t produce enough heat to create elements heavier than iron. Only supernovae are up to the job.
Next time you heat up a copper-bottomed saucepan on your cooker, reflect on the fact that the copper on the bottom of the pan can only have come from one place – the heart of a supernova. Somewhere a lot hotter than your cooker: in fact the hottest place in the universe.
Of course when it comes down to it, because of the fact that all of the elements are manufactured in stars of some sort, and in stars alone (apart from hydrogen and helium), that means that everything on earth is made of stardust – even things that you rarely associate with the cosmos. As illustrated in this cartoon.
Please don’t use this cartoon without permission. PLease go here instead.