Sense of Wonder: A Century of Science Fiction (459 page)

He had found it with software that searched the maps, looking for anything that was much longer than it was wide. This retrieved quite a few of the jets that zoomed out of regions near black holes, and sometimes from the disks orbiting young stars. He spent months eliminating these false signatures, looking for the telltales of compact stellar runaways. He then got time on the Very Large Array—not much, but enough to pull G369.23–0.82 out of the noise a bit better. This was quite satisfying.

Ralph got more coffee and went back and studied his paper, published less than half a year ago. Until today, that was the best data anybody had. He had looked for signs of rotation in the point-like blob in front, but there were none. The first runaway seen, the Mouse, discovered many years before, was finally shown to be a rotating neutron star—a pulsar, beeping its right radio beams out at the cupped ears of radio telescopes.

Then he compared in detail with Andy’s new map:

Clean, smooth, beautiful. He read the Conclusions section over again, mind jittery and racing.

We thus fail to confirm that G369.23–0.82 is a pulsar. Clearly it has a bow shock, creating a wind nebula, undoubtedly powered by a neutron star. Yet at highest sensitivity there is no trace of a pulsed signal in microwaves or optical, within the usual range of pulsar periods. The nebular bow shock cone angle implies that G369.23–0.82 is moving with a Mach number of about 80, suggesting a space velocity ≈ 120 km/s through a local gas of density ≈ 0.3 per cubic cm. We use the distance estimate of Eilek et.al. for the object, which is halfway across the galaxy. These dynamics and luminosity are consistent with a distant neutron star moving at a velocity driven by ejection from a supernova. If it is a pulsar, it is not beaming in our direction.

Beautiful work.
Alas.

The bright region blazed forth, microwave emission from high energy electrons. The innermost circle was not the neutron star, just the unresolved zone too small for even Arecibo to see. At the presumed distance, that circle was still bigger than a solar system. The bow shock was a perfect, smooth curve. Behind that came the microwave emission of gas driven back, heated and caught up in what would become the wake. At the core was something that could shove aside the interstellar gas with brute momentum. A whole star, squeezed by gravity into a ball about as big as the San Francisco Bay area.

But how had Andy gotten such fine resolution?

Ralph worked through the numbers and found that this latest map had picked up much more signal than his earlier work. The object was brighter. Why? Maybe it was meeting denser gas, so had more radiating electrons to work with?

For a moment he just gazed at the beauty of it. He never lost his sense of awe at such wonders. That helped a bit to cool his disgruntlement. Just a bit.

* * * *

There wasn’t much time between Andy’s paper popping up on the astro-ph web site and his big spring trip.

Before leaving, he retraced his data and got ahead on his teaching.

He and Irene finessed their problems, or at least delayed them. He got through a week of classes, put in data-processing time with his three graduate students, and found nothing new in the radio maps they worked on.

Then came their big, long-planned excursion. Irene was excited, but he now dreaded it.

His startup money had some travel funds left in it, and he had made the mistake of mentioning this to Irene. She jumped at the chance, even though it was a scientific conference in a small town—“But it’s in
France
,” she said, with a touch of round-eyed wonder he found endearing.

So off they jetted to the International Astronomical Union meeting in Briancon, a pleasant collection of stone buildings clinging to the French Alps. Off season, crouching beneath sharp snowy peaks in late May, it was charming and uncrowded and its delights went largely ignored by the astronomers. Some of the attendees went on hikes in the afternoon but Ralph stayed in town, talking, networking like the ambitious workaholic he was. Irene went shopping.

The shops were featuring what she called the Hot New Skanky Look, which she showed off for him in their cramped hotel room that evening. She flounced around in an off-the-shoulder pink blouse, artfully showing underwear and straps. Skanky certainly caught the flavor, but still he was distracted.

In their cramped hotel room, jet-lagged, she used some of her first-date skills, overcoming his distance. That way he got some sleep a few hours later. Good hours, they were.

The morning session was interesting, the afternoon a little slow. Irene did sit in on some papers. He couldn’t tell if she was interested in the science itself, or just because it was part of his life. She lasted a few hours and went shopping again, saying, “It’s my way of understanding their culture.”

The conference put on a late afternoon tour of the vast, thick-walled castles that loomed at every sharp peak. At the banquet inside one of the cold, echoing fortresses they were treated to local specialties, a spicy polenta and fresh-caught trout. Irene surveyed the crowd, half of them still wearing shorts and T-shirts, and remarked, “Y’know, this is a quirky profession. A whole room of terribly smart people, and it never occurred to them to try to get by on their looks.”

He laughed; she had a point. She was a butterfly among the astro-drones, turning heads, smiles blossoming in her wake. He felt enhanced to have her on his arm. Or maybe it was the wine, a Vin Local red that went straight to his head, with some help from the two kilometer altitude.

They milled around the high, arched reception room after the dessert. The crowd of over 200 was too energized to go off to bed, so they had more wine. Ralph caught sight of Andy Lakehurst then. Irene noted his look and said, “Uh oh.”

“Hey, he’s an old friend.”

“Oh? You’re glaring at him.”

“Okay, let’s say there’s some leftover baggage.”

She gave him a veiled look, yawned, and said. “I’ll wander off to the room, let you boys play.”

Ralph nodded, barely listening. He eavesdropped carefully to the crowd gathered around Andy. Lanky and with broad shoulders, the man’s booming voice carried well, over the heads of just about everybody in the room. Andy was going on about good ol’ G369.23–0.82. Ralph edged closer.

“—I figure maybe another, longer look at it, at G—”

“The Bullet,” Ralph broke in.

“What?” Andy had a high forehead and it wrinkled as he stopped in mid-sentence.

“It looks like a bullet, why not call it that, instead of that long code?”

“Well,” Andy began brightly, “people might mistake—”

“There’s even the smoke trailing behind it, the wake,” Ralph said, grinning. “Use that, if you want it to get into Scientific American.”

“Y’know, Ralph, you haven’t changed.”

“Poorer, is all.”

“Hey, none of us went into this to get rich.”

“Tenure would be nice.”

“Damn right, buddy.” Andy clapped him on the shoulder. “I’m going up for it this winter, y’know.”

He hadn’t, but covered with, “Well deserved. I’m sure you’ll get it,” and couldn’t resist adding, “Harvard’s a tough sell, though. Carl Sagan didn’t make it there.”

“Really?” Andy frowned, then covered with, “So, uh, you think we should call it the Rifle?”

“The Bullet,” Ralph said again. “It’s sure going fast, and we don’t really know it’s a neutron star.”

“Hey, it’s a long way off, hard to diagnose.”

“Maybe it’s distant, I kinda wonder—”

“And it fits the other parameters.”

“Except you couldn’t find a pulse, so maybe it’s not a pulsar.”

“Gotta be,” Andy said casually, and someone interrupted with a point Ralph couldn’t hear and Andy’s gaze shifted to include the crowd again. That gave Ralph a chance to think while Andy worked the room.

There were nearly a thousand pulsars now known, rotating neutron stars that flashed their lighthouse beams across the galaxy. Some spun a thousand times in a second, others were old and slow, all sweeping their beams out as they rotated. All such collapsed stars told their long tale of grinding decay; the slower were older. Some were ejected after their birth in bright, flashy supernovas—squashed by catastrophic compression in nuclear fire, all in a few minutes.

Here in Briancon, Ralph reflected, their company of smart, chattering chimpanzees—all evolved long after good ol’ G369.23–0.82 had emerged from its stellar placenta—raptly studied the corpses of great calamities, the murder of stars by remorseless gravity.

Not that their primate eyes would ever witness these objects directly. They actually saw, with their football-field sized dishes, the brilliant emissions of fevered electrons, swirling in celestial concert around magnetic fields. Clouds of electrons cruised near the speed of light itself, squeezing out their waves—braying to the whole universe that they were alive and powerful and wanted everyone to know it. Passing gaudy advertisements, they were, really, for the vast powers wrecking silent violences in the slumbering night skies.

“We’re out of its beam, that’s got to be the answer,” Andy said, turning back to Ralph and taking up their conversation again, his smile getting a little more rigid. “Not pointed at us.”

Ralph blinked, taken unaware; he had been vaguely musing. “Uh, I’m thinking maybe we should consider every possibility, is all.” Maybe he had taken one glass too many of the
Vin Local.

“What else could it be?” Andy pressed his case, voice tightening. “It’s compact, moving fast, bright at the leading edge, luminosity driven by its bow shock. A neutron star, charging on out of the galaxy.”

“If it’s as far away as we think. What if it isn’t?”

“We don’t know anything else that can put out emissions like that.”

He could see nearby heads nodding. “We have to think…” grasping for something…“uh, outside the box.” Probably the
Vin Local
talking.

Smiling, Andy leaned close and whispered through his tight, no-doubt-soon-to-be tenured lips, “Ol’ buddy, you need an idea, to beat an idea.”

* * * *

Definitely the
Vin Local,
yes.

He awoke next morning with a traffic accident inside his skull. Only now did he remember that he had exchanged polite words with Harkin, the eminence gris of the Very Large Array, but there was no news about getting some observing time there. And he still had to give his paper.

It was a botch.

He had a gaudy Powerpoint presentation. And it even ran right on his laptop, a minor miracle. But the multicolored radio maps and graphics failed to conceal a poverty of ideas. If they could see a pulsed emission from it, they could date the age and then look back along the track of the runaway to see if a supernova remnant was there—a shell of expanding hot gas, a celestial bull’s eye, confirming the whole theory.

He presented his results on good ol’ G369.23–0.82. He had detailed microwave maps of it, plenty of calculations—but Andy had already given his talk, showing that it wasn’t a pulsar. And G369.23–0.82—Ralph insisted on calling it the Bullet, but puzzled looks told him that nobody much liked the coinage—was the pivot of the talk, alas.

“There are enough puzzling aspects here,” he said gamely, “to suspend judgment, I think. We have a habit of classifying objects because they superficially resemble others.”

The rest was radio maps of various blobby radio-emitting clouds he had thought could be other runaways…but weren’t. Using days of observing time at the VLA, and on other dish systems in the Netherlands and Bologna, Italy, he had racked up a lot of time.

And found…nothing. Sure, plenty of supernova remnants, some shredded fragments of lesser catastrophes, mysterious leftovers fading fast in the radio frequencies—but no runaways with the distinctive tails first found in the famous Mouse. He tried to cover the failure by riffing through quick images of these disappointments, implying without saying that these were open possibilities. The audience seemed to like the swift, color-enhanced maps. It was a method his mother had taught him while playing bridge: finesse when you don’t have all the tricks.

His talk came just before lunch and the audience looked hungry. He hoped he could get away with just a few questions. Andy rose at the back and asked innocently, “So why do you think the, uh, Bullet is
not a neutron star?”

“Where’s the supernova remnant it came from?” Ralph shot back. “There’s nothing at all within many light years behind it.”

“It’s faded away, probably,” Andy said.

A voice from the left, one of the Grand Old Men, said, “Remember, the, ah, Bullet is all the way across the galaxy. An old, faint remnant it might have escaped is hard to see at that distance. And—” a shrewd pursing of lips—“did you look at a sufficiently deep sensitivity?”

“I used all the observing time I had,” Ralph answered, jumping his Powerpoint slides back to a mottled field view—random flecks, no structure obvious. “The region in the far wake of the Bullet is confusion limited.”

Astronomers described a noisy background with that term, meaning that they could not tell signal from noise. But as he fielded a few more quick questions he thought that maybe the jargon was more right than they knew. Confusion limited what they could know, taking their mayfly snapshots.

Then Andy stood again and poked away at details of the data, a bit of tit for tat, and finishing with a jibe: “I don’t understand your remark about not jumping to classify objects just because they superficially resemble other ones.”

He really had no good reason, but he grinned and decided to joke his way through. “Well, the Bullet doesn’t have the skewed shape of the Duck…”—which was another oddly shaped pulsar wake, lopsided fuzz left behind by a young pulsar Andy had discovered two years ago. “Astronomers forget that the public likes descriptive terms. They’re easier to remember than, say, G369.23–0.82.” Some laughter. “So I think it’s important to keep our options open. And not succumb to the sweet temptation to go sensational, y’know—” He drew a deep breath and slipped into a falsetto trill he had practiced in his room. “Runaway star! High speeds! It will escape our galaxy entirely!”