The Hubble Telescope recently captured images of a distant galaxy that contains an unusual amount of dust. The simple presence of this dust in such a small, dim and young galaxy, known as A1689-zD1, has scientists baffled, and can yield a lot of important information about the formation of the universe itself.
Possibly the greatest significance of this discovery is how it contradicts with what astronomers have come to understand about the presence of dust in the universe. Dust is formed when a star “dies”, releasing elements like carbon, oxygen and silicon in the process. Thus, galaxies considered to be “dusty” are usually expected to hold a high number of very old stars, which would make them appear brighter or larger than A1689-zD1 does.
This discovery is unique, not only because of the apparent presence of an unusual amount of dust, but also because it’s rather difficult to find galaxies similar to A1689-zD1, due to its distance and dimness. In order to learn more about this phenomenon, more young, dusty galaxies would need to be discovered, but one has not been found until this point.
The presence of the dust on A1689-zD1, which contains small, young stars, is essentially inexplicable. In this state, it is critical to a greater understanding of the origins of the universe because of its distance. Due to the time it takes light to travel to us, scientists observe the galaxy as it existed hundreds of millions of years ago – about 700 million years after the formation of the universe. Although, this may sound like a long time, in reality it is only a tiny fraction of the long life of the universe. Other galaxies of this age have been observed, but these celestial bodies are rather large, and provide less accurate representations of an “average” galactic system.
Upon discovering A1689-zD1, scientists expected to find a relatively basic galactic system, with a simple chemical makeup and no dust. What they found instead was a young galaxy with a complicated chemical makeup and lots of cosmic dust.
This marks the second major cosmic discovery in recent weeks. Just a week ago, an unusually massive black hole was uncovered. Both of these discoveries are seen as windows into the early universe, and are expected to bring us a step closer to grasping that nearly unfathomable point of origin.