Astronomers were rather surprised recently to come upon a strange sight: a young galaxy just a few hundred million years old filled with space dust.
Scientists have been studying galaxy A1689-zD1, a very, very distant galaxy that is so far away that we are looking at what it looked like billions of years ago when it was just a few hundred million years removed from the Big Bang, according to a Los Angeles Times report.
Although very faint, astronomers were able to spot the galaxy because its light was being bent by Abell 1689, a massive galaxy cluster that is between the smaller galaxy and Earth. The effect is similar to that of a magnifying glass, allowing the galaxy’s faint light to appear 9.3 times as bright as it otherwise would in a process known as gravitational lensing.
The galaxy has a similar ratio of dust and gas to our Milky Way, a galaxy that has been around a very long time. Why is that so surprising? Because such ratios are typically only found in older galaxies, not young ones that are not far removed from the Big Bang.
Scientists used the European Southern Observatory’s Very Large Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA) to make the observations of the star-birthing galaxy, which pumps out about 12 solar masses worth of stars each year.
Dust is considered a recent phenomenon for galaxies, as in the early universe, stars were made of hydrogen and helium, and then they died forming supernovae that blasted stardust into the cosmos that helped create future stars, which themselves died and eventually led to heavier and heavier elements to the point they created elements like carbon, which are essential to the creation of life.
Accumulating enough dust to do this would have taken eons — or so scientists thought until they encountered this galaxy. A galaxy this young, so soon removed from the Big Bang, should not have this must dust, they thought.
But at 700 million years old, its dust ratio rivals our own galaxy, despite the fact that the Milky Way dates to nearly the start of the universe.
It means scientists will have to go back to the drawing board so to speak to question some of the assumptions they have, and figure out how the galaxy pulled this off.