The Condor is the largest spiral galaxy yet seen, spanning about two million light-years. The galaxy was stretched out by a closer encounter with a smaller galaxy, which looks like a small disk just above the Condor's core. The smaller galaxy swept past the Condor, pulling out great streamers of stars and triggering the birth of millions more stars. The galaxy eventually punched through the Condor's disk, and is looping around for another pass. The two galaxies probably will merge in a few hundred million years. [ESO]
A pair of galaxies that’s more than 200 million light-years away is undergoing the galactic equivalent of a multi-car pile-up. Instead of destruction, though, the encounter produces life — a wave of starbirth that may have created millions of new stars.
The larger of the two galaxies is NGC 6872, also known as the Condor galaxy. It’s the biggest spiral galaxy yet seen, with two outstretched arms that sweep half a million light-years from tip to tip.
One reason the Condor’s wingspan is so large is because of a gravitational encounter with a second galaxy. Although this companion looks tiny compared to the Condor, it’s actually bigger than our own galaxy, the Milky Way.
About 130 million years ago, it began sliding past the Condor. Its gravity stretched out the Condor’s spiral arms. It also squeezed vast clouds of gas and dust in the arms, causing them to collapse and give birth to new stars — the “pile-up” part of their encounter.
The process continues today. The smaller galaxy appears to have punched through one of the long spiral arms, causing it to bend at a funny angle. The encounter created more stellar nurseries — the collapsing clouds where new stars are born.
And the process may continue for a while longer. The smaller galaxy may loop back around, triggering even more starbirth. Eventually, the two galaxies may merge — creating a true galactic supergiant.
Tomorrow: a really old rock from Mars.
Script by Damond Benningfield, Copyright 2014
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