An article published in “The Astrophysical Journal Letters” describes a research about the dwarf galaxy DDO 68. An international team of researchers led by Francesca Annibali of the National Institute for Astrophysics (INAF), Italy, used the Large Binocular Telescope (LBT) to make observations that allowed to find evidence that even a very small galaxy can capture smaller galaxies.

The dwarf galaxy DDO 68, also known as UGC 5340, is about 39 million light years away from Earth. Its total mass is around 100 million solar masses, very little if you think that the Milky Way is about a thousand times more massive and it’s not a particularly big galaxy. It’s a dwarf galaxy with an irregular shape, one of the characteristics that have intrigued astronomers.

DDO 68 is also one of the three galaxies poorest of chemical elements other than hydrogen and helium, a composition not very different from its original one that makes it seem this galaxy younger than it really is. The investigations of the reasons of the lack of heavier elements have been going on for some time and it’s possible that they were dispersed into space because the energy of the supernovae is stronger than this dwarf galaxy’s gravity.

The irregular shape of DDO 68 with a kind of tail consisting of stars and gas suggested that there are gravitational interactions with other celestial bodies. The researchers looked at the photographs of this dwarf galaxy taken by the Hubble Space Telescope and decided to ask to be able to use LBT to make specific observations. DDO 68 was considered an isolated galaxy, in the area of space where it was surrounded only by the cosmic void, but the researchers wanted to check this hypothesis.

With LBT the researchers were able to discover that DDO 68 has some satellites, galaxies even smaller than this dwarf galaxy and DDO 68 is slowly cannibalizing them. For this reason, the researchers used the metaphor of the flea with smaller fleas that on him prey inspired by the writer Jonathan Swift. This discovery proves that even very small galaxies can grow by merging with others, a process that was hitherto known in medium to large galaxies.

Francesca Annibali pointed out that DDO 68 doesn’t seem to be abel to retain the elements ejected by supernovas but still manages to attract other dwarf galaxies. Understanding the dynamics of the various events is the next step in the studies with specific investigations that demonstrate how seemingly uninteresting dwarf galaxies may instead be useful in scientific research.