Lit by the white light of the projector, the faces of the Presidium remained blank. Faraday, sitting next to Stepan, crossed his arms.
“Okay,” Stepan managed awkwardly, and brought up the next slide. “From the top. This is the data that the GBM squeezed from the burst we detected three weeks ago. As you can see, it’s a short-duration spike that tails away quickly. The spike peaked at precisely 17.59 mega-electron volts. We turned the satellite on the source after the burst was detected, but were unable to detect an afterglow.”
Gina Divero, representing Alpha-2, spoke up. “And that’s unusual?”
“Oh yes. The energies involved in the events which generate gamma ray bursts are…well, almost beyond description. So powerful that we’ve detected the afterglow of GRBs across thirteen billion light years.” Stepan skipped ahead a few slides to a series of pixelated images of orange and red spheres. “We’ve never detected one in the Milky Way because, not only are they exceedingly rare, but a GRB in the Milky Way would be nothing short of an extinction event.”
“But its says here,” Charles Clarendon, representing Alpha-3, read from his tablet, “that you established the point of origin?”
“We think so.” Stepan fumbled with the slides. “Without an afterglow, we could not measure the redshift of the light, and so could only determine a direction – not a distance. But along that path we quickly find – ”
A touch of Stepan’s fingertips to the tablet, and an animation was projected onto the wall that showed Alpha A and B orbiting their mutual barycentre. There was Fram, just for a moment, a delicate bead suspended on a line tracing its orbit; but then the image quickly panned out, and a line travelled away from the twin stars, passed Sol, bounced from a red marble labelled Lalande 21185, and intersected with another binary system far to its left. The image zoomed in on a small, red dwarf and its even dimmer companion.
“FL Virginis.” Stepan froze the image on the mysterious binary. “Or Wolf 424, if you prefer. A binary system of an M5-class red dwarf and an unknown companion, probably a high-mass brown dwarf. An utterly unremarkable system, cold and dim, deficient in metals and with little hydrogen. Barely more than a dozen light years away, so the source was clearly not a gamma-ray burst.”
Figures suspended on the lines between stars suggested that Lalande 21185 was equidistant from both Alpha Centauri and FL Virginis – 8.2 light years in each direction.
“But the source, this star, is a flare star, I read from your report,” Clarendon inquired.
“Yes,” Clarendon repeated, but in an expectant tone.
Gina asked, “Could this be the cause of the spike you detected?”
“That’s what I thought, at first,” Stepan responded, “but my colleague Elzette Skovgaard has spent much time refuting the theory. Flare stars unpredictably and dramatically increase in brightness along visual spectra. They’re usually red dwarfs, like FL Virginis A – ”
“And Proxima, yes?”
“ – and like Proxima. And they’re usually binary or trinary systems, where another member of the system might induce contortions in the star’s magnetic field. Like a solar flare. Using Proxima for data, she’s shown that flare stars can radiate in the visual spectrum, X rays and radio waves – but don’t tend to flare gamma rays. But I don’t want to step on Konrad’s toes here.”
Stepan slid his tablet to Faraday, who cleared his throat.
“Yes. And of note here is the precise energy detected by the satellite.” Faraday changed slides, and the figure 17.59 MeV appeared on the wall. “This is the precise amount of energy – the precise amount – shared by the high-energy neutron and an alpha particle formed in a thermonuclear reaction between a tritium and deuterium nucleus.”
“Tritium,” Clarendon repeated. “Deuterium.”
“Indeed,” Faraday continued, “and tritium occurs irregularly in nature. Occasionally in atmospheres containing hydrogen and nitrogen that interact with cosmic rays.”
Stepan spoke up. “And, as I noted before, the Virginis system is deficient in hydrogen.”
“And these other possibilities you mentioned here,” Gina asked, skimming the report quickly, “you discount each?”
“I thought, maybe, that we’d detected a magnetar or a pulsar, directly behind FL Virginis, visible through gravitational lensing. But look at that spike. It’s a one-off; it hasn’t repeated in the three weeks since its first detection. For the same reason, it’s not a soft gamma repeater. We’d see oscillations related to its rotation period. So then I thought that the red dwarf had developed an accretion disk, and that its companion was ploughing through that disk and generating pulses of gamma rays with each interaction. But we know the brown dwarf’s orbital period, just over sixteen years, and we’ve never detected a burst like this before –”
“We keep coming back to two things,” Faraday said impatiently. “First, FL Virginis is an unexceptional system. Second, the energy detected was precisely that of the fusion of deuterium and tritium.”
“And hence,” said Clarendon, in a low and foreboding voice, turning to the gathered members, “the closed session of the Presidium. You’re saying that, in a star system essentially two doors down, you’ve detected evidence of the detonation of a hydrogen bomb…”