Astronomers using data from the Euclid space telescope have discovered an exceptionally faint stellar system near the Fornax dwarf galaxy. Called Fornax-7, it appears to contain only about 170 times the mass of the sun in stars. The discovery paper was posted to the arXiv preprint server on Sept. 13.

The lambda cold dark matter model of the universe predicts that dark matter halos of any mass should host their own smaller subhalos. This is well established for galaxies with masses similar to the Milky Way’s, which have many dwarf satellites, but it has never been confirmed for hosts much less massive than the Milky Way.

The current record-holder is the Large Magellanic Cloud (LMC), which has candidate ultra-faint companions. Finding a satellite around something as small as the Fornax dwarf spheroidal galaxy (Fornax dSph), roughly 100 times less massive than the LMC, would extend “the observed hierarchical formation of satellite systems nearly two orders of magnitude below the LMC,” researchers write in the paper.