What happens to a star whose life is drawing to an end?|
These luminaries shone when in their prime,
But as the final curtain nears, which attributes attend?
Do they waste away and shrivel?
Or get rude and most uncivil?
Or just disappear with style and chic sublime?
It depends, of course, upon the kind of star that you might choose:
The Hollywood variety, perchance?
And all of their shenanigans that always make the news?
Or would you choose the kind
With which heaven's void is lined:
And are scattered through the cosmos' vast expanse?
The subject of this magazine demands the latter choice
(A checkout-counter tabloid this is not);
And so I'll choose the stars that make astronomers rejoice:
Those spheres of white-hot fusing
Hydrogen, which they keep using
To maintain their normal size and keep them hot.
So what happens to these stars when all their hydrogen's consumed?
Well, they're all so far away, it's hard to tell,
But according to the theories, even when a star is doomed
And its life is nearly through,
Then the next thing it will do
Depends upon its gravitational well.
See, a little star has insufficient mass and gravitation
To make a big display when once it dies;
Its fuel used up, it undergoes a gradual transformation
Where it cools, and then grows dark,
Leaving not a single spark
Of the splendor that it had ere its demise.
A star of somewhat larger mass and gravity will die
With significantly more than just a "pop."
Its gravity will cause some different physics to apply:
When its hydrogen is gone,
Then the helium's light lives on,
Since its gravity's compression heats it up.
So the helium starts to fuse, and a brand-new lease on life
Is now granted to this star of medium mass.
But then the helium's ash (that's carbon) in the stellar core gets rife
And the star again compresses
Under gravitational stresses
And so iron, fused from carbon, comes to pass.
Well, this iron core is stubborn, and resists attempts to fuse
Into anything more dense than iron at all,
But the grav'ty of this star of medium mass is loathe to lose
When it fights atomic forces
So its tendency, of course, is
Just to squeeze it all into a neutron ball.
This "neutron star," as it is called, is just exactly that:
The pressure got so high in its collapse,
That electron shells of atoms, in their white-hot habitat,
Just cave in, and burst asunder,
Nuclear forces knuckling under,
And neutrons all crowd in and fill the gaps.
Now, as you can well imagine, since an atom's mostly space,
A neutron star is dense beyond belief.
Just try to grab a teaspoonful and take it anyplace:
The hundred million tons in weight
Would crush your spine to such a state
You'd hardly be much more than bas-relief.
So now, you ask, what happens when a star's so very large
Even neutrons can't resist gravitic squeeze?
Ah, well, that's another duty I will faithfully discharge,
In an issue not yet printed
(As he shrewdly, subtly hinted),
Assuming that the publisher agrees!