Waiting on a Dead WorldBrian H. Gill
They grew in the light of a golden sun. They studied the soil, stones and waters around them. They studied the stars and fire. They studied the myriad forms of life around them. And they recorded what they had learned.
They lived, engendered more of their kind, watched their young grow and learn, and they died. But their sun continued to shine, and their young grew old, studied, and added to the store of knowledge.
Stars do not grow old, as living things do: but stars change.
As their store of knowledge increased, they came to know that in time their star's inner fires would fail, choked in ash which had accumulated over ages beyond imagining.
Armed with that knowledge, they could prepare.
Some decided to accept the end of their world as their own end, and the end of all who would come after, accepting what was to come.
Others built tiny worlds, moving them as the once-golden sun grew and dimmed - but not enough to spare its inner worlds. They lived, grew, engendered and died: and learned. In time some of them grew restless, turned their eyes to the stars; left the shrunken, glaring ember that had been their sun behind; and sought other suns.
A few would not die with their world, and would not leave. They had learned, long ago, how to record their memories, habits and desires in forms which could endure boiling oceans and the hot wind which swept air from their home.
And so, as their star billowed out, puffing its substance into the void, they left copies of their minds, buried under miles of rock. Not as inert patterns of memory and habit: but active as their living forms had been. For in this way they thought that some part of themselves, at least, would endure.
And endure they did: as their sun burned the last of its fuel and shrank to a white-hot spot in the sky of their now-airless world. At last they ventured up, in mechanical bodies well-suited to the vacuum and cold.
Standing on a dead world, their sun a point of light which would have pained living eyes, they discovered that near-immortality was not quite as satisfactory as they had imagined.
Their artificial bodies were adequate, but did not provide the quality of sensation which they remembered.
Some learned to be content with their new form.
Others decided that they wanted to taste, to smell, to touch as they once had. They wanted to live as creatures of flesh and blood again.
It was not a futile desire. The methods they had used to inhabit mechanical bodies could be used to impose their will on organic creatures, and draw sensations from the living hosts.
There was nothing living on their world. But, they reasoned, just as some of their own kind had traveled the void between stars, others might come to their world.
So they built a huge pattern of concentric rings, surrounded by a pulsing radiance which could have no natural source.
And they waited.
After a very long time, a moving point of light appeared in their sky. It drifted down, until even living eyes could have recognized a mass of cylinders and spheres: a vessel built to carry living beings from world to world.
The vessel landed, opened, and living creatures stepped out. And were met by the waiting minds.
It was worth the wait.
Here's what got me started:
"Dead Stars Once Hosted Solar Systems"If mathematical models that stellar physicists and cosmologists have made are anywhere near being accurate, a star like our sun has roughly 12,000,000,000 years from the time it starts shining to the point at which its supply of hydrogen in the core runs out.
Space.com (April 20, 2009)
"At least one in every 100 white dwarf stars may be orbited by asteroids and rocky planets, new observations from NASA's Spitzer Space Telescope suggest. The finding could mean that these now dead stars once hosted solar systems similar to our own....
"...White dwarf stars are the compact, hot remnants left behind when stars like our own sun reach the end of their lives....
With the fusion fire out, the star starts shrinking - which pushes hydrogen outside the core to pressures and temperatures where fusion will take place. The star starts expanding at this point, becoming a red giant (boiling the oceans of any formerly-habitable planet(s) it may have had) - and eventually forming a pretty-looking nebula around the now-spent interior of the star. The process takes a few million years - something like a thousandth of the star's time on the main sequence.
(I'm leaving out quite a few steps - there's a decent discussion of stellar evolution at the Stellar Database, "Stellar Evolution.")
What's left collapses into a ball smaller than Uranus or Neptune. This object is a white dwarf. Back to that Space.com article:
"...The atmospheres of white dwarfs usually consist entirely of hydrogen and helium, but sometimes heavier elements such as calcium or magnesium are detected contaminating the stellar material.
"Data from Spitzer suggest that at least 1 to 3 percent of white dwarf stars are contaminated in this way.
"Scientists think that the out-of-place elements come from a gradual rain of orbiting dust onto the sun. The dust emits infrared radiation which Spitzer detects.
"The dust is entirely contained within what is called the Roche limit of the star, or close enough that any object larger than a few kilometers would be ripped apart by gravitational tides. (This is the same phenomenon that produced Saturn's rings.) Because of the location of the dust, scientists think that the dust may originate from rocky bodies such as asteroids (also known as minor planets) that were torn apart in this way.
"This could mean that as many as 5 million white dwarfs in our own Milky Way are surrounded by orbiting asteroids.
"For the asteroids to get within the Roche limit to be pulled apart at the seams, they must be perturbed from an orbit farther out from their star — the asteroids could be nudged by as yet unseen planets...."