The Lion’s Treasure
I like to look at pictures of galaxies. They always trigger in my mind questions about what kind of life must exist on planets around their stars. Since we’ll likely never know (at least in our lifetimes) about beings in other galaxies, it’s a great way to think about starry empires and the civilizations that support them. As a science person, I look at galaxies and immediately start cataloguing in my mind their structures, which gives me some idea of their evolutionary history— that is, what they went through to get to the shape we see them in—and also how much star-forming activity is occurring in the arms. Galaxies are treasure houses of star formation, star death, and the materials for new stars, planets, and life.
This galaxy, NGC 3521, is what astronomers call a “flocculent” spiral galaxy. That means its spiral arms are fluffy with clouds of gas and they are dotted with star-forming regions. The areas where new stars are being born are mostly blue in color because of the hot young ultraviolet-bright stars they contain. The reddish areas contain older stars, and the dark lanes are those clouds of gas and dust. There could be stars forming inside those clouds and in a few tens of thousands of years, bright blue splotches will light up more regions of the dust lanes.
The core of this galaxy is really quite compact—meaning tightly bound together. There are likely millions of stars in that little region, and possibly a black hole. All in all, this is a busy galaxy—bustling with star formation, and with the creation of many stars, very likely it has a population of planets in orbit around some of those stars. If so, I expect that this treasure of a galaxy in Leo also has some life forms in it—maybe some of them are looking at pictures of our galaxy and wondering the same things about the Milky Way.
