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NGC 1232: A Colossal Cosmic Crash
(April Hobart, CXC): If the majestic pinwheel structure of this galaxy wasn't beautiful
enough, the pink halo gives this photograph a magical finish. Yet, what we're actually
seeing here is pretty violent. In this picture, a galactic collision is taking place between
the grand spiral galaxy and the tiny dwarf galaxy that you can see to its left. The pink
mist is actually a huge cloud of gas, burning at millions of degrees Celsius, which forms
when these galaxies clash! This cloud is mostly invisible to our eyes but the gas shines brightly
with high-energy X-ray light at extremely high temperatures.
Near the "head" of this comet-shaped fog, you can see an area with a group of very bright
stars. The energy of the crash may have caused a boom of star formation here. Powerful explosions
from dying stars and cosmic gale-force winds coming from hot, bright stars help keep the
cloud shining brightly with X-rays.
As for how big this cloud is, it's difficult to measure. We struggle to determine the shape
of distant cosmic objects. We only have flat, 2-dimensional images to work with and it's
not like we can fly behind them to take a look! Is this pink mist thin and shaped like
a pancake? Or is it thicker, like a fat rain cloud? Until we know the shape, we can't be
sure just how big it is. If it is thin like a pancake then it will have 40,000 times the
mass of our Sun. If it is more spherical, it would be more like 3 million times as massive
as our Sun!