This image of Sextans B was taken with Nicholas U. Mayall’s 4-meter telescope and shows red-colored star-forming regions near the center of the galaxy. There are several bright stars around the galaxy that are much closer to us in our galaxy. They are identified by the criss-cross patterns created by light interacting with the structure of the telescope, as well as numerous blurry-looking background galaxies that appear small because they are much further away than Sextans B. KPNO / NOIRLab / NSF / AURA data received and processed by: P. Massey (Lowell Obs.), G. Jacoby, K. Olsen and C. Smith (AURA / NSF) Image processing: TA Rector (University of Alaska Anchorage / NOIRLab from NSF), M. Zamani (NOIRLab from NSF) and D. de Martin (NOIRLab from NSF)
Galaxies in our universe come in a variety of sizes, such as the giant IC 1101, which is 50 times the size of the Milky Way and up to 8 million light years in diameter – which is why it is known as the Godzilla Galaxy. At the other end of the scale, you’ll find relatively small galaxies only 200 light years across, like the tiny Segue 2.
However, the fact that a galaxy is tiny does not mean that it is not of scientific interest, as this image of the dwarf galaxy Sextans B shows. The dwarf galaxy is 4.5 million light years away and has a mass 200 million times the mass of the sun. It is only a few thousand light years across. Even so, it is home to a whole host of astronomical phenomena that are compressed into their relatively small size.
The most obvious features are the bright red clouds near the center of the image made of hydrogen. These are the birthplaces of stars where the clouds clump together and eventually create an attraction strong enough to form a new star.
The galaxy contains not only the star nurseries, but also their graveyards in the form of planetary nebulae. Sextans B are among the smallest galaxies with planetary nebulae. These are beautiful ring-shaped structures that arise when a red giant star approaches the end of its life, although they are not visible in the picture. When a star runs out of fuel, it sheds its outer layers, which form elaborate structures in space.
The picture was taken with Nicholas U. Mayall’s 4-meter telescope at Kitt Peak National Observatory and shows, in addition to Sextans B, many other galaxies in the background that appear out of focus, as well as stars in our galaxy that are much closer to us and shine so bright.