Scientists Announce Discovery of Most Distant Galaxy
BALTIMORE (AP) _ Astronomers on Monday announced the discovery of the most distant galaxy known, a cluster of stars 15 billion light years away that formed long before the Earth and the sun.
″This is very unusual and very rare,″ said Ken Chambers of Johns Hopkins University, one of the co-discovers. ″We’re seeing something from before the Earth formed, possibly before our own galaxy, and when the universe was very different than today.″
The distant galaxy, known as 4C41.17, is far too faint to be seen by the eye, but it emits a radio signal a billion times more powerful than the sun’s radio signal.
″It is one of the most powerful radio galaxies we know of,″ said Chambers.
Though the galaxy was located by radio signals, its distance from Earth was established by analyzing the optical spectrum, or type of light, put out by the galaxy.
Chambers said the galaxy puts out a sharp optical signal of the type characteristic of hydrogen and carbon. The wavelength of the emission, however, is stretched by movement away from the observer.
This stretch causes the light color to shift toward red, the so-called ″red shift.″ By measuring this shift, the astronomers could calculate the distance of the galaxy.
A red shift of 3.8 found for 4C41.17 shows that it is about 15 billion light years away. A light year is the distance light travels in a year, about 5.8 trillion miles.
Chambers said at 15 billion light years, the galaxy is about 90 percent of the distance to what is thought to be the edge of the universe. He said it also gives a view back in time and the galaxy as seen now is only few billion years after the Big Bang, the massive explosion that is thought to have started the universe expanding outward.
The galaxy is thought to be ″primitive,″ or in an early stage of formation, Chambers said.
″To be able to study the dynamics as it is forming will tell us a lot of how galaxies are formed,″ he said.
The Earth and sun are thought to have formed about 4.6 billion years ago.
The study of the distant galaxy was announced at the 20th assembly of the International Astronomical Union. Chambers’ co-discovers were George Miley, a European Space Agency representative at the Space Telescope Science Institute, and Wil van Bruegel, an astronomer at the University of California, Berkeley.