Updated

Updated · Livescience.com · Jun 12

Small Magellanic Cloud Expands at 38,000 mph as Large Magellanic Cloud Tears It Apart

Updated

Updated · Livescience.com · Jun 12

Small Magellanic Cloud Expands at 38,000 mph as Large Magellanic Cloud Tears It Apart

Q: A neighboring galaxy is being devoured. Is this cosmic cannibalism the ultimate fate of all smaller galaxies?

No. Galactic “cannibalism” is a common fate for many small galaxies, but not an unavoidable end for every one of them. The new Magellanic Clouds study shows how this works in real time. By tracking stellar motions over more than a decade, researchers found the Small Magellanic Cloud is not behaving like a simple rotating disk. Its stars are streaming outward along a specific axis, strong evidence that the Large Magellanic Cloud is tidally pulling it apart. That is a textbook case of tidal stripping: gravity removes stars, gas and dark matter from a smaller satellite. Astronomers already know this is a major engine of galaxy growth. The Milky Way itself was built partly by absorbing smaller systems, leaving behind stellar streams and other debris. Simulations and observations show the same process across the universe: large galaxies accrete small ones, and even dwarf galaxies can consume still smaller companions. But “ultimate fate of all” is too strong. A small galaxy’s future depends on its environment, orbit and mass. Satellites that pass close to a larger galaxy are especially vulnerable to disruption. More isolated dwarfs, or those on wider, less destructive orbits, can survive for billions of years. Some are transformed rather than destroyed, losing gas and outer stars while retaining a bound core. So the broader answer is that cosmic cannibalism is fundamental to galaxy evolution, especially for satellites in dense environments. It is widespread, not universal.

3 articles · Updated · Livescience.com · Jun 12

More than a decade of VISTA observations shows nearly all stars in the Small Magellanic Cloud moving outward at about 38,000 mph, revealing a galaxy-wide tidal disruption rather than localized disturbance.
Their southeast-northwest motion points to the Large Magellanic Cloud as the driver, overturning the long-held view that the smaller galaxy behaves like a rotating disk.
At that pace, stars could shift several thousand light-years within a few hundred million years, enough to significantly distort the Small Magellanic Cloud and possibly split it in two.
The finding strengthens earlier hints of opposing stellar motions and suggests repeated encounters between the two dwarf galaxies have shaped the Magellanic system over billions of years.
Researchers said the result could reshape understanding of the Milky Way's 60-plus dwarf satellites, with a new VISTA-based survey due later this year to map motions toward and away from Earth.

Sources

Livescience.com1d ago

Small Magellanic Cloud Ripped Apart by Large Magellanic Cloud's Gravitational Pull

Yahoo! Voices1d ago

I was really amazed': On the edge of the Milky Way, a dwarf galaxy is being ripped in half by its big sibling

Facebook1d ago

205-minute mosaic of Large Magellanic Cloud from Middlemarch, Otago, New Zealand

4 Sources

Astronomers were wrong about a nearby galaxy's spin. How many other galaxies are we fundamentally misunderstanding?

A galactic collision is revealing primordial secrets. What else will this cosmic brawl uncover before its final act?

A neighboring galaxy is being devoured. Is this cosmic cannibalism the ultimate fate of all smaller galaxies?

The Small Magellanic Cloud’s Demise: Real-Time Evidence of a Galaxy Torn Apart by Tidal Forces from the Large Magellanic Cloud

Overview

The Small Magellanic Cloud (SMC), a close neighbor of the Milky Way, is being dramatically torn apart by the powerful gravitational pull of the Large Magellanic Cloud (LMC). Instead of rotating like a typical galaxy, the SMC’s stars are moving outward in a large-scale expansion, especially along a southeast–northwest axis. This outward motion is a clear sign of tidal stretching caused by repeated encounters with the LMC over billions of years. As a result, the SMC is now in a highly disturbed state, with chaotic and radial stellar motions, showing that it is slowly coming apart.

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