Astronomers Are Finally Able To See The Most Distance Galaxy Ever
- Author: Tracy Ferguson Mar 12, 2017,
Mar 12, 2017, 0:27
With this data, the team was able to estimate how long it takes for the dust that ALMA detected to form.
Now, researchers have observed this process taking place during the universe's extreme infancy, in a galaxy called A2744_YD4, using the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope (VLT), both in northern Chile. It was seen when the universe was only about 4 percent of its present age, which put it at around 600 million years old.
Redshift measures the amount by which a distant object's light is stretched by the expansion of the universe. Thus, A2744_YD4 is one of the earliest pieces of the universe. It's also important to note that redshift is not linear - redshifts of 0-1 are considered relatively nearby, while redshifts of 8-9 are some of the farthest objects we can now see as we look back to the very early universe.
This artist's impression shows what the very distant young galaxy A2744_YD4 might look like. Findings indicate stars started to form when just 400 million years after the dawn of the universe.
Understandably, getting a clearer picture of the formative years of the universe - the era when the first stars and galaxies "switched on" - is of vital interest to scientists. As neutral hydrogen throughout the universe was ionized, however, light could finally travel vast distances. An global team led by Nicolas Laporte of the University College of London spearheaded the search, then used ESO's Very Large Telescope to follow up and confirm the distance of A2744_YD4.
A2744_YD4 is full of dust.
Stardust is the leftovers from star explosions, or supernovae, when the star has reached the end of its life.
Cosmic stardust is made up of silicon, carbon and aluminium. Our Sun, our planet and our existence are the products - 13 billion years later - of this first generation of stars. This is despite the fact that the earliest universe has the least probability of having its first-generation stars die out to leave behind stardust in such high quantities. The team also measured the rate of star formation in A2744_YD4 and found that stars are forming at a rate of 20 solar masses per year - compared to just one solar mass per year in the Milky Way. "Remarkably, the required time is only about 200 million years - so we are witnessing this galaxy shortly after its formation". This was possible by looking at a galaxy called A2744_YD4 which appeared to us as if the universe was in extreme infancy.
Population III (Pop III) stars theoretically contain only hydrogen, helium, and very little if any "heavier" elements, such as lithium. (As a note, astronomers typically refer to any elements heavier than helium as "metals", regardless of their classification on the periodic table.) Pop III stars probably began developing about 100 million years after the Big Bang. Because the galaxy is so young and remote, they were not expecting to see it contained a huge mass of glowing stardust, which would have formed from an earlier generation of stars dying. This was around the same time that the first stars and galaxies were formed. Our Sun is a Pop I star, and the metals found inside it and our solar system can all be traced back to the same type of supernovae that spread dust (and metals) throughout A2744_YD4. The ALMA observations are also the most distant detection of oxygen in the Universe. This is due in part to a gravitational effect from a large cluster of galaxies between us and A2744_YD4 that bends the light from the distant galaxy and acts as a giant magnifying lens.
In a recent development, a group of astronomers have detected the youngest and by far, the farthest galaxy ever seen by mankind.