A group of astronomers has spotted the youngest and farthest galaxy ever seen by the Atacama Large Millimeter Array (ALMA). The galaxy known as A2744_YD4 is surrounded by stardust, which is dust originated from the death of earlier stars.
The galaxy is so far away that astronomers see it as it looked like when the universe was 600 million years old. According to research, the universe can be as old as 13.8 billion years old, so the sighting of the new galaxy is remarkable.
The group was led by Nicolas Laporte, an astronomer at University College London that shared his amusement when they viewed the remote galaxy through the Atacama Large Millimeter/submillimeter Array or ALMA.
“Not only is A2744_YD4 the most distant galaxy yet observed by ALMA, but the detection of so much dust indicates early supernovae must have already polluted this galaxy” explained Laporte in a statement.
Supernovae explosions
Star or interstellar dust is composed of tiny grains of silicon, carbon, and aluminum. These elements are found inside stars and other celestial bodies, so when a star dies in a supernova explosion, the elements are scattered around the universe. The elements turn into dust, which has a significant role in forming new stars, planets and celestial bodies. Interstellar dust is quite common in today’s universe, but in the earlier stages of the universe, it was scarce.
The elements turn into dust, which has a significant role in forming new stars, planets and celestial bodies. Interstellar dust is quite common in today’s universe, but in the earlier stages of the universe, it was scarce.
The discovery has made possible for astronomers to get a peek of a younger universe, plus the detection of the dust shed some light on the time the first supernovae exploded and hence the time when the first hot stars filled the universe with light. Supernovae are calculated to appear once every 600 years, but there were practically none in the early days of the universe.
Abell 2744
The observation of the young galaxy was only possible because this galaxy lies behind a massive galaxy cluster called Abell 2744. Because of a phenomenon called gravitational lensing, the astronomers were able to use Abell 2744 as a giant space “telescope,” which allowed them to magnify the distant galaxy by about 1.8 times.
The team estimates that A2744_YD4 contained an amount of dust equivalent to 6 million times the mass of our sun, and they estimated that the mass of the total of stars in the galaxy was 2 billion times the mass of the sun.
The astronomers also measured the rate of star formation on A2744_YD4 and found that the stars formed at a rate of 20 solar masses per year. Star formation in the Milky Way only goes as fast as one solar mass per year, but they agree that the rate for A2744_YD4 isn’t unusual for such a distant galaxy, considering the amount of dust around the galaxy.
The required time for the formation is about 200 million years, so the astronomers believe that they encountered A2744_YD4 shortly after its formation. The study provides an excellent opportunity for ALMA to study the early stages of our universe and the era when galaxies started appearing.
Source: Science Daily