Mysterious galactic glow caused by Hitchhikers' Krikkit style stars

The mysterious background glow of the universe is probably caused by "orphan" stars leading an isolated existence wrapped in clouds of dark matter, according to a new analysis by top boffins reviewing data from NASA's Spitzer telescope far out in space.

Scientists have long been puzzled by the levels of background infrared light that telescopes see, as it is brighter than can be accounted for by the trillions of stars shining from the known galaxies of the universe. Various theories have been advanced to account for the discrepancy, for instance the suggestion that we can't see all the galaxies there are - either because they are even more outrageously far away than the ones we can see, or because they aren't quite so far off but are really old and thus rather faint.

Now, however, allied astronomers sifting the Spitzer telescope's imagery of a patch of sky in the constellation Boötes say they have come up with another and better idea.

"The idea of not-so-far-away faint galaxies is [wrong]," says Edward Wright, UCLA astro-boffin. "It's off by a factor of about 10; the 'distant galaxies' hypothesis is off by a factor of about 1,000."

Instead, Wright and his colleagues theorise that the haloes of "dark matter" surrounding the observed galaxies are not entirely dark. Rather they contain a thin scattering of lonely stars, each wrapped in the dark surrounding clouds, whose light makes the darkness glow faintly and invisibly in the infrared.

"You can't see the dark matter very well, but we are proposing that it actually has a few stars in it — only one-tenth of 1 percent of the number of stars in the bright part of the galaxy," explains Wright. "One star in a thousand gets stripped out of the visible galaxy and gets distributed like the dark matter."

If such a star had any planets, it would be quite possible (depending on orientation with respect to the local galaxy) that its night skies would be entirely dark to the naked eye, like those of the fictional planet Krikkit created by Douglas Adams of Hitchhikers' Guide to the Galaxy fame. Krikkit's surrounding cloak of dark matter was not the thin stuff of an extragalactic halo, but a more impenetrable cloud produced by the disintegration of a colossal supercomputer: nonetheless as Adams fans we here on the Reg boffinry desk have chosen to note the similarities rather than the differences.

We wouldn't go so far as to say that the Spitzer discoveries foretell a terrible galactic war fought by legions of genocidal white robots with a strong resemblance to cricket players, as waged by the natives of the planet Krikkit in Life, the Universe and Everything. But it makes for a nice headline.

The new astronomy research is published in hefty boffinry mag Nature. ®