Ghostly Remnants of Galaxy Interactions Captured with Telescope

First Posted: Aug 05, 2015 02:11 PM EDT

Astronomers have spotted the ghostly remnants of galaxy interactions in a nearby galaxy group. They've taken a closer look at the nearby spiral galaxy M81 together with its two brightest neighbors, M82 and NGC3077 and have discovered a bit more about their interactions with one another.

The current, favored cosmological galaxy models are based on the idea of hierarchical structure formation. Essentially, structures in the universe such as galaxies develop from small "overdensities" to become large-scale objects. For example, the Milky Way and M81 first formed as part of a local over-density; the earliest accumulations of matter in the young universe accumulated in the form of numerous smaller building blocks that then came together to form the galaxies.

In this latest study, the researchers decided to learn a bit more about galaxy evolution by studying the three galaxies. They used the Hyper-Suprime-Cam (HSC) to look at M81, which is about 11.7 million light-years away and is one of the nearest massive spiral galaxies. In addition to M81, the researchers captured 18 known member galaxies of the M81 group.

The scientists found that the bright stars are mainly located in the inner disk of M81, while most of the young stars in outlying concentrations are fainter and have similar luminosity distributions as that of the stellar stream between M81 and NGC 3077. They are between 30 to 160 million years old. The ages of the stars in these tidal features are actually synchronized to each other, and these systems were actually produced by recent tidal interactions between M81, M82 and NGC 3077.

"Our deep panoramic view of the M81 group demonstrates that the complexity long known to be present in neutral hydrogen (HI) is equally matched in the low surface brightness stellar component," said Sakurako Okamoto, one of the researchers, in a news release. "Together with the Galactic Archaeology study based on the HSC wide-field survey of the Subaru Strategic Program, we hope to establish the presence and nature of satellite galaxies, and determine the large-scale structure and stellar content of halos of spiral galaxies in general."

The findings are published in The Astrophysical Journal.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone

TagsGalaxy, Evolution, Stars, NASA