Astronomers have been pondering the riddle of the quasars for more than 30 years, wondering what prodigious energy source could possibly make these starlike objects visible from halfway across the universe. The leading theory: a quasar is gas falling into a gigantic black hole. As the gas is compressed, it heats up to millions of degrees, glowing brightly enough to outshine an entire galaxy; occasionally, jets of hot gas spray out, like juice squirting from a squeezed orange.
Since quasars lie billions of light-years from earth, astrophysicists thought they might never prove the theory. But radio astronomers report in the current issue of Nature that they have discovered something similar to a quasar in the Milky Way galaxy, right in our own cosmic backyard. The object is much less powerful than a typical quasar, but it appears to work on the same principle. And being a mere 40,000 light-years away, it will be easier to study.
What the astronomers actually saw was a radio hot spot, caused by a jet of subatomic particles spewing from the object at nearly the speed of light. (Because of its angle, the jet gives the illusion of moving faster than light, a physical impossibility.) The jet presumably comes from gas falling from an orbiting companion star into a black hole that weighs as much as a handful of stars. Typical quasars, in contrast, emanate from something with the mass of a million stars or more. Unfortunately, galactic dust largely hides the mini-quasar, so there is a limit to how much astronomers will be able to learn from it. But since they have found one, they might find others. And that could give them plenty of clues to help solve cosmic riddles.