Actually it was Jau Xin's pilot-zipheads who had done the flying. Nau nodded at Xin. "That was good work, Pilot Manager."

Xin grinned. "Thank you, sir. Something to tell my children about."

Reynolt ignored the comment. She popped up multiple windows, showing low-altitude views in various spectral regimes. "We've had a hard time with the analysis right from the beginning."

They could hear the recorded voices of the two zipheads now. Li was Emergent-bred, but the other voice spoke in a Qeng Ho dialect. That must be Wen: "We've always known OnOff has the mass and density of a normal G star. Now we can make high-resolution maps of the interior temperatures and dens—" Dr. Li butted in with the typical urgency of a ziphead, "—but we need more microsats....Resources be damned. We need two hundred at least, right through the time of Relighting."

Reynolt paused the audio. "We got them one hundred microsats." More windows popped up, Li and Wen back at Hammerfest after the Relight, arguing and arguing. Reynolt's reports were often like this, a barrage of pictures and tables and sound bites.

Wen was talking again. He sounded tired. "Even in Off-state, the central densities were typical of a G star, yet there was no collapse. The surface turbulence is barely ten thousand kilometers deep. How? How? How?"

Li: "And after Relight, the deep internal structure looks still the same."

"We can't know for sure; we can't get close."

"No, it looks perfectly typical now. We have models... ."

Wen's voice changed again. He was speaking faster, in a tone of frustration, almost pain. "All this data, and we have just the same mysteries as before. I've spent five years now studying reaction paths, and I'm as clueless as the Dawn Age astronomers. Therehas to be something going on in the extended core, or else there would be a collapse."

The other ziphead sounded petulant. "Obviously, even in Off state the star is still radiating, but radiating something that converts to low-interaction."

"But what? What? And if there could be such a thing, why don't the higher layers collapse?"

"Cuz the conversion is at the base of the photosphere, and thatis collapsed! Ryop. I'm using your own modeling software to show this!"

"No. Post hoc nonsense, no better than ages past."

"But I've gotdata !"

"So? Your adiabats are—"

Reynolt cut the audio. "They went on like this for many days. Most of it is a private jargon, the sort of things a close-bound Focused pair often invents."

Nau straightened in his chair. "If they can only talk to each other, we have no access. Did you lose them?"

"No. At least not in the usual way. Dr. Wen became so frustrated that he began to consider random externalities. In a normal person that might lead to creativity but—"

Brughel laughed, genuinely amused. "So your astronomer laddie lost sight of the ball, eh, Reynolt?"

Reynolt didn't even look at Brughel. "Be silent," she said. Nau noticed the Peddlers' startlement at her words. Ritser was second-in-command, the obvious sadist among the rulers—and here she had abruptly put him down.I wonder when the Peddlers will figure it out. A scowl passed briefly across Brughel's features. Then his grin broadened. He settled back in his chair and flicked an amused glance in Nau's direction. Anne continued without missing a beat: "Wen backed off from the problem, setting it in a wider and wider context. At first, there was some relevance."

Wen's voice resumed, the same rushed monotone as before. "OnOff's galactic orbit. A clue." The presumptive graph of OnOff's galactic orbit—assuming no close stellar encounters—flashed in a window. Anne was dredging from the fellow's notebooks. The plot extended back over half a billion years. It was the typical flower-petal figure of a halo-population star: Once every two hundred million years, OnOff penetrated the hidden heart of the galaxy. From there, it swung out and out till the stars spread thin and the intergalactic dark began. Tomas Nau was no astronomer, but he knew that halo-pop stars don't have usable planetary systems, and as a result aren't often visited. But surely that was the least of the strangeness of OnOff.

Somehow the Qeng Ho ziphead had become totally fixated on the star's galactic orbit. "This thing—it can't be a star—has seen the Heart of All. Again and again and again—" Reynolt skipped through what must have been a long, trapped loop in poor Wen's thinking. The ziphead's voice was momentarily calmer: "Clues. There are lots of clues, really. Forget the physics; just consider the light curve. For two hundred and fifteen years out of two hundred and fifty, it radiates less perceptible energy than a brown dwarf." The windows accompanying Wen's thoughts flickered from idea to idea, pictures of brown dwarfs, the much more rapid oscillations that the physicists had extrapolated for OnOff's distant past. "Things are happening that we can't see. Relight, a light curve vaguely like a periodic Q-nova, settling over a few Msecs to a spectrum that might almost be an explainable star riding a fusion core. And then the light slowly fades back to zero... or changes into something else we cannot see. It's not a star at all! It's magic. A magic machine that now is broken. I'll bet it was a fast squarewave generator once. That's it! Magic from the heart of the galaxy, broken now so that we can't understand it."

The audio abruptly ended, and Wen's kaleidoscope of windows was fixed in mid-frenzy. "Dr. Wen has been thoroughly trapped in this cycle of ideas for ten Msec," said Reynolt.

Nau already knew where this was going, but he put on a concerned look anyway. "What are we left with?"

"Dr. Li is doing okay. He was slipping into his own contrarian cycle till we separated him from Wen. But now—well, he's fixated on the Qeng Ho system identification software. He has an enormously complex model that matches all the observations." More pictures, Li's theory of a new family of subatomic particles. "Dr. Li is spreading into the cognitive territory that Hunte Wen monopolized, but he's getting very different results."

Li's voice: "Yes. Yes! My model predicts stars like this must be common very near the galaxy's hole. Very very rarely, they interact, a strongly coupled explosion. The result gets kicked high out of the core." Of course, Li's trajectory was identical to Wen's after the presumed explosion. "I can fit all the parameters. We can't see blinking stars in the dust of the core; they're not bright and they're very high-rate. But once in a billion years we get this asymmetrical destruction, and an ejection." Pictures of the hypothetical explosion of OnOff's hypothetical destroyer. Pictures of OnOff's original solar system blown away—all except a tiny protected shadow on the far side of OnOff from the destroyer.

Ezr Vinh leaned forward. "Lord, he's explained just about everything."

"Yes," said Nau. "Even the singleton nature of the planetary system." He turned away from the jumble of windows, and looked at Anne. "So what do you think?"

Reynolt shrugged. "Who knows? That's why we need an unFocused specialist, Podmaster. Dr. Li is spreading his net wider and wider. That can be a symptom of a classic, explain-everything trap. And his particle theory is large; it may be a Shannon tautology." She paused. Anne Reynolt was totally incapable of showmanship. Nau had arranged his questions so her bombshell came out last: "That particle theory is in his central specialty, however. And it has consequences, perhaps a faster ramscoop drive."

No one said anything for several seconds. The Qeng Ho had been diddling their drives for thousands of years, since before Pham Nuwen even. They had stolen insights from hundreds of civilizations. In the last thousand years, they'd made less than a one-percent improvement. "Well, well, well." Tomas Nau knew how good it felt to gamble big...and win. Even the Peddlers were grinning like idiots. He let the good feeling pass back and forth around the room. It was veryvery good news, even if the payoff was at the end of the Exile. "This does make our astrophysicists a precious commodity. Can you do anything about Wen?"