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In this case, the speedster star is known as
Kappa Cassiopeiae, or HD 2905 to astronomers.
It is a massive, hot supergiant moving at around
2.5 million mph relative to its neighbors (1,100
kilometers per second).
But what really makes the star stand out in
this image is the surrounding, streaky red glow
of material in its path. Such structures are called
bow shocks, and they can often be seen in front
of the fastest, most massive stars in the galaxy.
Bow shocks form where the magnetic fields and
wind of particles flowing off a star collide with
the diffuse, and usually invisible, gas and dust
that fill the space between stars. How these shocks
light up tells astronomers about the conditions
around the star and in space. Slow-moving stars
like our sun have bow shocks that are nearly invisible
at all wavelengths of light, but fast stars like
Kappa Cassiopeiae create shocks that can be seen
by Spitzer’s infrared detectors.
(Courtesy: NASA)
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