“The only astronomical phenomenon I can think of that’s that straight and that long is a Type I comet tail,” Bram said. “Except that there’s no coma at one end. In fact, the brightest part, if I read the instruments right, is in the middle.”
“Yes,” Jun Davd agreed. “And it doesn’t extend outward from where the mass indicators say our shrouded star ought to be. It’s tangent to it.”
“So that suggests very strongly that it has something to do with the structure that’s enclosing the star. And that those curved scratches—the arcs and hooks—are part of the same manifestation.”
Jun Davd turned to face him: Somehow Jun Davd managed to be limber, even in the bulky envelope of the human-shaped space suit that had been developed during the last ten years of deceleration by a team under the direction of Lydis. He had the toe of one heavy boot hooked under the horn of a cleat to check his outward drift, and his long-limbed body swiveled halfway around at the hips with a natural grace. He was not one of those people you saw bobbing around at the end of their safety ropes and having to haul themselves in.
“I agree. I have a computer working on an analysis of the curvatures to see what kind of a three-dimensional shape we can make them fit into. But clearly, we’re looking at an artifact.”
Artifact. Bram tasted the word with disbelief. From the size of the infrared emission shell, the unseen sun ought to have been a red giant—a swallower of solar systems. An artifact of that radius at the center of the Father World’s system would have engulfed the two inner planets and the Father World itself.
“A trap around a star,” Bram said slowly. “A trap for energy. When we first began searching for an enclosed star radiating in the ten-micron part of the spectrum, I somehow visualized something like a sphere. I think we all did.” He paused to stare again at the distant wonder. “It’s hard to imagine how any rectilinear material body the size of that could maintain its shape without gravitationally collapsing.”
“There’s only one answer, then. It’s not straight.”
Bram looked again, but the line was just as straight as before. “It’s not?” he said.
“We’re looking at the illuminated limb of another geometric form,” Jun Davd said. “One that can maintain its shape. I can think of at least two: a cylinder and—”
“Yes,” Bram breathed. “A disk. A spinning disk. Seen edge-on. But it’s still unbelievable.”
“We don’t know what was possible to Original Man at the height of his glory. Perhaps, given another forty or fifty thousand years, the Nar might have learned how to utilize the total energy of a sun.”
“Do you really think that’s Man’s sun in there?”
Jun Davd wrinkled his brow. “One of the suns he used, perhaps. The sun that gave him birth, no. I can’t see him dismantling his own father world to make a beacon. There’s nothing in this system larger than an asteroid. Nothing but a swarm of comets orbiting an invisible mass. And we’re lucky he left us the comets.”
He broke off to stare across the miles at the cagework trumpet bell of the ramscoop, which was no longer bathed in the spilled energies that had made it bright. A couple of comets had already been stuffed down its throat as start-up fuel for the next intersystem hop—the hop that the absence of worlds here had made unavoidable.
A space tug floated nearby, waiting to field the next slushball to be sent onward. Two tugs, actually, with a five-mile-wide net strung between them. It was the net that was visible as a fleck of light from a reflected spotlight beam. Bram wondered if his daughter Lydis was one of the pilots.
Closer at hand, against the fibrous wall of the root system across the way, a work crew was prying another ensnared comet away from Yggdrasil—a small one, less than a mile in diameter. With his magnification up, Bram could just make out the tiny space suited figures. They were melting away the clinging ice with dozens of two-man torches. It would require exquisite nicety of timing on the part of the foreman to make sure that the frozen sphere broke loose at just the right moment to cast it toward the waiting tugs instead of outward into the dark.
Yggdrasil could spare a few comets. Scores of the captured iceballs beaded the thirsty surface of its root hemisphere. The tree was working bravely to redistribute mass, but the unassimilated treasure trove still caused a wobble in the crown that took some getting used to. There was a lot of dropped glassware in the living quarters these days, but nobody was complaining. Abundance had returned to the tree after the long drought. The pools were filled, there was boating in the lagoon again, and water sports in the spherical pond at the center of the trunk. More important was the increase in metabolic products as Yggdrasil went through a growth spurt—sugars, starches, complex resins, and new cellulose for the factories.
Bram remembered the excitement when they had entered this queer, gutted system. Four previous ten-micron emission sources had proved to be false alarms—supergiants with circumstellar emission shells that were probably heated dust grains, not worth slowing down for. But the fifth candidate had shown all the symptoms of what the search team had jokingly taken to calling “Jao’s shell.”
It was Jao who first had proposed the theory of an enwrapped star whose output—by whatever unknown means—had been translated into the cosmos-spanning radio waves of Original Man’s beacon.
“Where’s all that building material going to come from?” Smeth had scoffed.
“From the dismantled planets,” Jao had replied. “And maybe they’d have to haul over the planets from a couple of nearby systems, too. They’d be turned into some kind of supermaterial made mostly of hydrogen, carbon, and oxygen—the atmospheres of a couple of gas giants mixed with the goodies at the core, and some cometary ice—you get the picture.”
“How are you going to keep the shell from drifting off center?” Smeth had expostulated. “And if it rotates, how do you keep its substance from collecting at the equator?”
“Details,” Jao had replied airily. “We’ll worry about them later. The main thing is to look for infrared sources that fit the basic picture.”
The search area had been narrowed down to a sphere a thousand light-years in diameter. The Nar, long ago, had pinpointed an approximate location for Original Man’s sun by analyzing wave fronts on a line stretched between the Father World and the new outpost on Juxt, and they had arrived at a value for the galactic year at that radius. Jun Davd, during the thirty-seven-million-year head-on approach to the Milky Way, had refined the figure still further. When the M supergiants and the small hot objects shining through dust had been eliminated, the number of candidates was small. Even so, it was surprising to have found it, apparently, on the first try.
“I calculate a total energy output for our invisible sun of four times ten to the thirty-third power ergs per second,” Jun Davd had announced shortly after Yggdrasil had settled into a cometary orbit. “That’s based on the number of ergs per square inch falling on our collectors and applying the figure to an imaginary sphere at the radius of our own orbit. All in the deep infrared! It’s consistent with the normal output at all wavelengths of a G-type dwarf similar to both Original Man’s presumed sun and the Father World’s primary. An attractive sun for our type of life, and the Nar’s.”
Jao had worked out approximate orbital periods for the first few comets Yggdrasil had chased. “Yah,” he’d said. “The comets are moving at the right speed for the postulated mass at the center. Maybe just a little bit high—but, like I said, the beacon builders might’ve dragged in an extra gas giant or two from another system.”