Credit: NASA,
ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration,
and A.
Evans (University of Virginia, Charlottesville/NRAO/Stony Brook
University)
Not all galaxies are neatly shaped, as this new NASA/ESA Hubble Space Telescope image of NGC 6240 clearly demonstrates. Hubble previously released an image of this galaxy back in 2008, but the knotted region, shown here in a pinky-red hue at the centre of the galaxies, was only revealed in these new observations from Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys.
NGC
6240 lies 400 million light-years away in the constellation of
Ophiuchus (The Serpent Holder). This galaxy has an elongated shape with
branching wisps, loops and tails. This mess of gas, dust and stars bears
more than a passing resemblance to a butterfly and, though perhaps less
conventionally beautiful, a lobster.
This bizarrely-shaped galaxy
did not begin its life looking like this; its distorted appearance is a
result of a galactic merger that occurred when two galaxies drifted too
close to one another. This merger sparked bursts of new star formation
and triggered many hot young stars to explode as supernovae. A new
supernova was discovered in this galaxy in 2013, named SN 2013dc. It is not visible in this image, but its location is indicated here.
At
the centre of NGC 6240 an even more interesting phenomenon is taking
place. When the two galaxies came together, their central black holes
did so too. There are two supermassive black holes within this jumble,
spiralling closer and closer to one another. They are currently only
some 3000 light-years apart, incredibly close given that the galaxy
itself spans 300 000 light-years. This proximity secures their fate as
they are now too close to escape each other and will soon form a single
immense black hole.
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