Wed. Jan 26th, 2022

These streams cannot be resolved into individual stars and thus appear as elongated, diffuse light features with an angular extent of several arcminutes. Detecting them requires long-exposure, wide-field images encompassing the outskirts of the host galaxies. Working with amateur astroimagers over the last decade, we have imaged nearby spiral galaxies as part of the Stellar Tidal Stream Survey.

This observational effort has discovered almost 50 previously undetected tidal streams around our targets. The extraordinary variety of faint structures is compelling evidence that supports the hierarchical nature of galaxy formation predicted by the standard cosmological model.

In addition to circular features similar to the Sagittarius stream surrounding the Milky Way, our data have revealed enormous structures resembling open umbrellas with long, narrow shafts. These terminate in a giant shell of debris extending many thousands of light-years into space, often on both sides of the host galaxy.

We have also found isolated shells, giant clouds of debris floating within halos, jetlike spikes emerging from galactic disks, giant plumes, and large-scale diffuse structures. All of these are possibly related to the remnants of ancient satellites that are now thoroughly disrupted.






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