Neutron stars are some of the most extreme objects in the solar system,
and I simply couldn't wait any longer to get to the really exciting
stuff!
Episode 4 Synopsis:
After a much longer than usual jump through space the crew have found themselves a long way from home. The crew are clearly nervous about this and the captain asks SAI where they are. SAI responds "The orders given to me were a little vague sir, I have brought you to the nearest, smallest and most powerful star I could find", she has brought them to a neutron star 424 lightyears from Earth. On the monitor is a very distant and very small star, the crew don't really know what to make of it, seeing this SAI explains what the object they are looking at is a very rare and powerful star despite only being about 20km in diameter. The crew want to move closer but SAI informs them that moving closer is too dangerous. Readings are taken, showing that the star has a surface temperature of over 10million K and spewing out radio and x-rays from its rapidly rotating magnetic poles. The captain makes the decision to leave while they can, but the ship has used most of it's fuel getting here, unable to get close enough to the neutron star to gather energy they are stranded a very long way from home.
Episode Research:
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| The size relative size of a neutron star next to the island of Manhattan. |
As I already mentioned, Neutron stars are some of the most extreme objects in the universe, the mass of 8 to 10x that of our sun compressed into a truly tiny sphere only 20km across, and spinning hundreds of times per second. Virtually everything about neutron stars are extreme!
Neutron stars are not born this way, they are the remnants of old massive stars and the process is quite complicated, I will explain the steps necessary.
'Main Sequence' stars generate their energy by converting hydrogen into helium, when the star has converted enough of the hydrogen (burnt enough fuel) reactions in the core stop causing it to contract. Reactions in the outer shell continue which causes the outer shell to expand into a 'red giant' phase.
If the star is massive enough then after this phase ends the star will not contract into a white dwarf as with smaller stars, instead it will violently collapse causing a supernova, shedding the large outer layer. The core is left behind as a Neutron star, most of the mass of the star is retained in this tiny core.
Neutron stars spin extremely fast at first, up to hundreds of times per second. This is because the rotation of the spinning red supergiant is maintained as the star contracts extremely quickly, much like when an ice skater brings in their arms to speed up a spin. All of the momentum is retained but on a much smaller object. Very slowly over time this spinning slows down.
At their moment of creation neutron stars can be up to 1,000,000,000,000K but emit energy so quickly that this cools quickly to around 10,000,000K.
The extreme rotation of neutron stars causes them to have very strong magnetic fields, the magnetic poles are not necessarily aligned to the poles of the stars rotation.
Some neutron stars emit radio and x-rays and are named 'Pulsars', this is because the radio and x-rays are emitted from the magnetic poles, which rotate rapidly as the star rotates. This is detected as a 'pulse' as the beam passes quickly over the onlooker.
The gravity of a neutron star is so extreme that any object falling towards it is accelerated to such an extent that upon impact it is destroyed on an atomic level, instantly becoming identical to the matter making up the star.
The closest neutron star to Earth is PSR_J0108_1431 at 424 lightyears from Earth, and is the setting for this episode. This particular neutron star is a very old 'Pulsar' and has slowed to rotate every 0.8 seconds.
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