In a Galaxy Far, Far Away

I recently read an article on entitled “Old Stardust in Young Galaxy Sheds Light on the First Stars.” The article, by Hanneke Weitering, talks about a dusty galaxy named A2744_YD4 that lives in the constellation Sculptor which lies behind a group of galaxies referred to as Pandora’s Cluster. A2744_YD4 is the youngest galaxy observed in Chile by the European Southern Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA), and is 13 billion light-years away from Earth. Because it is so far away, astronomers see A2744_YD4 as it appeared when the universe was just 600 million years old. It was observed that A2744_YD4 has a lot of dust which indicates that there had to have been a supernova explosion since those explosions leave behind dust and gas clouds. Galaxy A2744_YD4’s mass of its stars adds up to 2 billions times the suns mass, and new stars are forming 2o times faster than the Milky Way’s current star formation.

Below is an artists interpretation of Galaxy A2744_YD4.


I can connect this article to our sixteenth conceptual objective, “I can compare the Milky Way Galaxy to other galaxies.” As we learned in class discussion, the mass of the Milky Way is 1 trillion solar masses; therefore, our galaxy is much larger than Galaxy A2744_YD4 which has a mass of only 2 billion solar masses. Also, in the lecture tutorial “Galaxy Classifications,” we looked at pictures of a few different galaxies and had to classify them and provide descriptions for what helped us distinguish the differences. From this tutorial, I know that the Milky Way Galaxy is a barred spiral galaxy because it is more oval in shape ad does not have regions of active star formation. From this tutorial, I can infer that Galaxy A2744_YD4 is a spiral galaxy. Because of the artist’s interpretation, I see a central bulge that looks to be made up of dust/gas, and old stars, which is a classification of a spiral galaxy.

I really liked this article. It was interesting to me that astronomers found that this very young galaxy actually has a lot of dust from old stars. Learning about the different types of galaxies was one of my favorite conceptual objectives to learn about because I honestly did not know that there were types of galaxies until we started learning about it. I thought a galaxy was a galaxy in general.



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