In a recent study, astronomers reported the discovery of a giant tidal tail of stars associated with F8D1, the closest known example of an ultradiffuse galaxy (UDG). A member of the M81 group, this galaxy is located 12 million light-years away on the border between the constellations Ursa Major and Camelopardalis.

Astronomers using the Subaru Telescope and the Canada-France-Hawaii Telescope discovered a giant diffuse tail of a star, stretching 200,000 light-years away from a galaxy F8D1.

The presence of a tail means that the galaxy has recently interacted with another galaxy. This is crucial information for understanding how so-called “ultra-diffuse” galaxies are created. It is also compelling evidence that the galaxy has been heavily shaped by events over the past billion years.

This is the first time such a stellar stream has been found in a UDG. The research team hypothesizes that F8D1 was disrupted by a recent encounter with the giant spiral M81, which dominates the group in which F8D1 is found.

Since F8D1 is on the edge of the study area, only one tidal arm can be seen extending to the northeast. The team will now look for a countercurrent in the southwest.

Magazine reference:

  1. Rokas ┼Żemaitis, Annette MN Ferguson et al. A tale of a tail: a tidally disrupted ultradiffuse galaxy in the M81 group. Monthly communications from the Royal Astronomical Society. DOI: 10.1093/mnras/stac3133