z8_GND_5296 is a galaxy which, after its discovery in October 2013, was announced as one with the greatest redshift that has been confirmed through the Lyman-alpha emission line of hydrogen, putting it among the oldest and most distant known galaxies at approximately 13 gigalight-years (4.0×109 pc) from Earth. It is “seen as it was at a time just 700 million years after the Big Bang […] when the universe was only about 5 percent of its current age of 13.8 billion years”. The galaxy is at a redshift of 7.51, and it is neighbour to what was announced then as second most distant galaxy with a redshift of 7.2. The galaxy in its observable timeframe was producing stars at a phenomenal rate, equivalent in mass to about 300 suns per year.
The light reaching Earth from z8_GND_5296 left that galaxy over 13 billion years ago, corresponding to a distance of over 13 billion light-years (13 gigalight-years). In accordance with the prevailing theory of an expanding universe, the observed position of the galaxy is now much farther away, about 30 gigalight-years (9.2 Gpc) (comoving distance) from Earth.
Research published in the October 24, 2013 issue of the journal Nature by a team of astronomers fromThe University of Texas at Austin led by Steven Finkelstein in collaboration with astronomers at theTexas A&M University, the National Optical Astronomy Observatories and University of California, Riverside, describes discovery of the most distant galaxy known using deep optical and infraredimages taken by the Hubble Space Telescope. Their discovery was confirmed by the W. M. Keck Observatory in Hawaii. MOSFIRE (a new instrument on the Keck Telescope that is extremely sensitive to infrared light) proved instrumental to this finding.
To measure galaxies at such large distances with definitive evidence, astronomers use spectroscopyand the phenomenon of redshift. Redshift occurs whenever a light source moves away from an observer. Astronomical redshift is seen due to the expansion of the universe, and sufficiently distantlight sources (generally more than a few million light years away) show redshift corresponding to the rate of increase in their distance from Earth. The redshift observed in astronomy can be measured because the emission and absorption spectrafor atoms are distinctive and well known, calibrated from spectroscopic experiments in laboratories on Earth.