Galaxies are the great islands in the universe where stars live out their lives. But over the course of a galaxy’s evolution, there are times when it is active with more star formation than others, like this gorgeous example of NGC 1672 courtesy of the Hubble Space Telescope:
You really want to click that image to see the large version or, if you’re keen to experience the finer details, get the amazingĀ 5302×3805 version.
You’re welcome š
As I was saying, galaxies evolve over time and go through periods where there is a lot more star formation going on than others. NGC 1672 is one of those active galaxies, with star formation taking place not only in the spiral arms, but also in its nucleus as well:
NGCĀ 1672 is a type of galaxy known as a Seyfert galaxy. Galaxies typically have quiet nuclear regions – that is, they are dominated by older stars and have very little activity going on in those parts. Seyfert galaxies are quite different from typical spiral galaxies in that their nuclei are are very bright and are typically active with star formation, which you can easily see in the close-up.
So what’s going on here? The answer may lie in the fact that NGC 1672 is also a barred spiral galaxy. The Hubble image shows the central region of the galaxy but this ground-based image shows NGC 1672 in all of its barred-spiral glory:
As you can see, the bar is chocka-block of stars, gas, and dust that orbit the core in a highly inclined orbit. In other words, the gas is largely “aimed” toward the supermassive black hole at the very center. This in turn creates an accretion disk around the black hole which makes for a very bright nucleus.
But it also means that there is a lot of moving material in the outer region of the nucleus as well, and that means star formation around the nucleus!
There’s still a lot about barred spirals that we don’t yet know. Our own home galaxy contains a bar as well and barred spirals are not uncommon. Astronomers believe that bars are temporary but many questions remain. How do bars form? How long do they last? When do they form – do the form early in the galaxy’s evolution or late? And perhaps most interesting, why do they form in the first place?
There are lots of other little amazing details in the image, and I invite you to grab theĀ 5302×3805 versionĀ and start digging around. The brightest stars are foreground stars that live right here in the Milky Way, but there are lots galaxies deep in the background, some of which can be seen through NGC 1672, like this one:
Notice the color of this galaxy – that’s not because the background galaxy is really that color, but because it’s blue light is scattered by the dust in NGC 1672 itself, letting the yellow, orange, and red light through, giving the background galaxy a caramel color. Pretty cool!
There’s lots of beautiful gems in this image so dig away!
