Astronomers Announce Discovery of Most Distant Galaxy to Date

It may go by the ungainly astronomical catalog name Z8 GND 5296, but this new discovery is the most distant galaxy yet found in our universe. Researchers announced their find on October 23, 2013 in the journal Nature. The research team found this  highly-redshifted object mind-numbing billions of light-years away from us.

When they view Z8 GND 5296 through telescopes on or near the Earth, astronomers are actually looking back in both space and time to a mere 700 million years after the Big Bang; science estimates the current age of the cosmos as approximately 13.8 billion years old.

Z8 GND 5296: Redshift vs. Blushift

When celestial objects move toward the observer, they appear more blue in color, and when they move away from the same observer, they appear more red. Astronomers rate the apparent “shift” in color using scales that are known as either blueshift or redshift.

In the case of Z8 GND 5296, the distant galaxy has a redshift of 7.51, indicating that it’s moving away from us at a tremendous distance, as larger numbers indicate a greater distance from the observer. Until the new discovery, another galaxy, with a redshift of 7.21, held the title “most distant galaxy.”

A team of astronomers from the the University of Texas-Austin, University of California-Riverside, Texas A&M University and the National Optical Astronomy Observatories discovered the record-breaking Z8 GND 5296 in April, 2013.

Using optical and infrared imagery gathered by NASA’s Hubble Space Telescope, the team was then able to confirm the results on the ground using the MOSFIRE or Multi-Object Spectrometer for Infra-Red Exploration instrument mounted inside the W.M. Keck Observatory’s Keck I telescope. The Keck Observatory is up at an elevation of 4,145 meters near the summit of volcanic Mauna Loa on the island of Hawaii.

New Stars in Distant Galaxy

In their Nature article, the discovery team reported that Z8 GND 5296 is rich in heavy elements (they determine this by observing the colors as well) and is producing new stars rapidly, many more massive than the Sun. Z8 GND 5296 is also a small galaxy that is only 1 to 2 percent the mass of the Milky Way. Of course, using the terms “is rich in…” and “is producing…” are relative. Since all this happened billions of years ago, Z8 GND 5296 is unlikely to exist today. Regardless, we can learn a lot about our universe by peering into the distant past.

Principal investigator Steven L. Finkelstein, of the University of Texas-Austin, told the BBC World Service online, “One very interesting way to learn about the universe is to study these outliers and that tells us something about what sort of physical processes are dominating galaxy formation and galaxy evolution…What was great about this galaxy is not only is it so distant, it is also pretty exceptional.”

Resources:

Finkelstein, S.L. et al. A Galaxy Rapidly Forming Stars 700 Million Years after the Big Bang at Redshift, and Supplementary Information. (2013). Nature. Accessed October 24, 2013.

Morelle, Rebecca. New galaxy ‘most distant’ yet discovered. (2013).  BBC News Online. Accessed October 24, 2013.

Goudfrooij, P., Kruijssen, J. The Optical Colors of Giant Elliptical Galaxies and their Metal-Rich Globular Clusters. (2013). Space Telescope Science Institute. Accessed October 24, 2013.