Hubble Uncovers One of the Youngest and Brightest Galaxies in the Early Universe
Date: 11 February 2008
Satellite: Hubble Space Telescope
Depicts: Abell 1689, A1689-zD1
Copyright: NASA, ESA, L. Bradley (Johns Hopkins University), R. Bouwens (University of California, Santa Cruz), H. Ford (Johns Hopkins University) and G. Illingworth (University of California, Santa Cruz)
The left-hand image shows the massive cluster of yellowish galaxies Abell 1689 as seen by Hubble's Advanced Camera for Surveys (ACS).
The cluster's gravity acts as a gravitational lens, bending and magnifying the light of galaxies located far behind it. The faraway galaxies appear in the Hubble image as arc-shaped objects around the cluster. The increased magnification allows astronomers to study remote galaxies in greater detail.
One galaxy is so far away, however, it does not show up in the optical-light image taken with ACS (top, right), because its light is stretched to infrared wavelengths by the Universe's expansion.
Astronomers used Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and NASA's Spitzer Space Telescope with its Infrared Array Camera (IRAC) - with help from the gravitational lensing cluster - to see the faraway galaxy.
The distant galaxy, dubbed A1689-zD1, appears as a greyish-white smudge in the close-up view taken with Hubble's NICMOS (centre, right), and as a whitish blob in the Spitzer IRAC close-up view (bottom, right). The galaxy is brimming with star birth. Hubble and Spitzer worked together to show that it is one of the youngest galaxies ever discovered. Astronomers estimate that the galaxy is 13 thousand million light-years away. Abell 1689 is 2200 million light-years away.
A1689-zD1 was born during the cosmic dark ages, a period in the early Universe when the first stars and galaxies were just beginning to burst to life. The dark ages lasted from about 400 000 to roughly a thousand million years after the Big Bang. Astronomers think that A1689-zD1 was one of the galaxies that helped end the dark ages with its onset of stellar birth.
The ACS images were taken in 2002, the NICMOS images in 2005 and 2007, and the Spitzer IRAC images in 2006.
