Explanation:
Gorgeous spiral
galaxy M33 seems to have more than its fair share
of hydrogen.
Its inner 30,000 light-years
are shown here in an image processed
to fully reveal the reddish glow of ionized hydrogen regions
(HII regions)
sprawling along loose
spiral arms as they wind toward the galaxy's core.
Historically of
great interest to astronomers, M33's
giant HII regions are some of the
largest known stellar
nurseries - sites
of the formation of short-lived but very
massive
stars.
Intense ultraviolet radiation from the luminous, massive stars ionizes
the surrounding hydrogen gas and ultimately produces the
characteristic red glow.
A prominent member of the
local group of
galaxies,
M33 is also known as the
Triangulum Galaxy
and lies about 3 million light-years distant.
