Cosmic Times

Cosmic Times

Age of the universe:
10-25 billion years
Size of the universe:
25 billion light years

QUASARS: Express Trains to Netherworlds

Image of the quasar 3C 273

Image credit: Bachall et al., ApJ 450, 486 (1995)

Quasar 3C 273

Astronomers have discovered a quasar racing towards the edge of the known universe at a speed of 450 million miles per hour – that's two-thirds of the speed of light. This and other newfound quasars aren't just fast, they are really bright. The fact they are visible to us Earthlings means these strange objects must be fantastically bright. It's surprise inside of a surprise that's cloaked in mystery, since nobody really knows what quasars are.

For years, radio astronomers have been spotting what they called quasi-stellar objects (quasars). Five years ago astronomers managed to match one with a visible-light object seen in telescopes. But it was only two years ago that astronomers Jesse Greenstein and Maarten Schmidt managed to split the visible light of quasar 3C 273 into its spectrum of colors.

What they found in the spectrum was amazing. The lines in the spectrum which normally show the presence of certain elements, were shifted dramatically to the red side of the spectrum. This is the optical equivalent of a train whistle's tone dropping as the train moves away at high speed. In the case of 3C 273, however, the red-shift corresponded to an unheard of speed of 16 percent of the speed of light. That's more than 100 million miles-per-hour.

The same technique was used by Schmidt and Allan Sandage to find the speed of the record holder called quasar BSO-1. Sadly, neither Sandage nor anyone else can yet explain what BSO-1 is.

"We do know that [quasars] provide us with the long-sought keys to determine the size and shape of the universe," Sandage reported.

They also are confident that at least one theory is not true: quasars are probably not coded messages from a super-civilization, as has been suggested by Russian astronomer Nikolai Kardashev. It's highly unlikely, say the U.S. astronomers, that any civilization could broadcast messages with the power of 10,000 billion Suns which seems to be the power of these objects.

If there is any message from quasars, it is from the universe itself. Many astronomers hope that by seeking out and measuring the distance to more quasars using the 200-inch Mount Palomar telescope, they can see some of these objects that started shining when the universe was just seven percent of its current age. Some of that light, perhaps 15 billion years old, is only now reaching Earth. •

A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC