VISTA Finds 17 km/s Tidal Stretching in Small Magellanic Cloud by Larger Sibling
Updated
Updated · Space.com · Jun 7
VISTA Finds 17 km/s Tidal Stretching in Small Magellanic Cloud by Larger Sibling
3 articles · Updated · Space.com · Jun 7
Summary
11 years of VISTA observations show the Small Magellanic Cloud’s stars are streaming outward rather than rotating, revealing large-scale tidal expansion across the dwarf galaxy.
17 kilometers per second is the average outward stellar speed, and the motion aligns on a southeast-northwest axis that points back to the Large Magellanic Cloud, matching a tidal-pulling scenario.
The result overturns earlier interpretations that treated the Small Magellanic Cloud as a rotating disk and suggests repeated encounters with the Large Magellanic Cloud have distorted it over billions of years.
Older red giant stars also show a bulk northward drift tied to an interaction about 2 billion years ago, hinting the pair’s past was shaped before their current close pass by the Milky Way.
Astronomers say both Magellanic Clouds are now slowing in the Milky Way’s halo and are expected to merge with our galaxy in billions of years, after continuing to evolve together first.