Hidden ‘tail’ found behind the spiral galaxy, M61- Here is what study says

Hidden ‘tail’ found behind the spiral galaxy M61 (Image: NSF–DOE Vera C. Rubin Observatory/NOIRLab)

Astronomers have made a striking discovery reshaping our view of galaxies. A faint stellar “tail” has been found behind the spiral galaxy M61. The feature suggests a long-forgotten collision with a smaller companion galaxy. This breakthrough offers new insight into how galaxies evolve and merge.

Astronomers have uncovered a faint stellar stream behind galaxy M61. This hidden “tail” was spotted using the Vera C. Rubin Telescope. It marks the first stellar stream ever detected by the telescope. The finding offers new clues about the galaxy’s mysterious formation history.

The research was conducted by a team led by Aaron J. Romanowsky of San José State University (USA), together with co-authors including David Martínez‑Delgado (Spain) and Giuseppe Donatiello (Italy).

They analysed deep-field images captured during the telescope’s early survey phase. The Rubin team noticed a faint, elongated structure trailing behind M61. Further analysis revealed it was debris from an ancient galactic collision.

The galaxy M61 lies about 52 million light-years away. It sits within the Virgo Cluster of galaxies in space. The scientists used imaging data from the Vera C. Rubin Observatory (Chile) during its “First Look” commissioning survey. The Rubin Telescope, based in Chile, captured these remarkable new images.

The Rubin Telescope’s powerful sensors can capture extremely dim structures. Its wide-field imaging allowed astronomers to map faint stellar trails. The stream’s brightness was just above the telescope’s detection threshold. The future observations will confirm its age, motion and composition accurately.

This faint tail could change our understanding of M61’s evolution. Scientists believe it formed when M61 absorbed a smaller galaxy. This violent merger likely shaped M61’s spiral arms and inner stars. It also shows how galactic interactions drive long-term cosmic transformation.

This research opens a new era for studying galactic evolution deeply. Rubin’s future surveys may uncover many more hidden stellar streams. Such data will reveal how galaxies grow through cosmic collisions. Each faint trace helps decode the long, violent story of the universe.