Astronomy Picture of the Day

Bright Spiral Galaxy M81 in Ultraviolet from Galex

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Bright Spiral Galaxy M81 in Ultraviolet from Galex

Where are the hot stars in M81, one of the closest major spiral galaxies?

To help find out, astronomers took a deep image in
ultraviolet light
of the sprawling spiral with the Earth-orbiting
Galex telescope.

Hot stars emit more ultraviolet than cool stars, and are frequently associated with young
open clusters of stars and energetic
star forming regions.

spiral galaxy M81, slightly smaller in size to our own
Milky Way Galaxy,
shows off its young stars in its winding spiral arms in the
above image.

Less than 100 million years old, the young stars are blue in the
above false-color Galex image and seen to be well separated from the
older yellowish stars of the galactic core.

Visible above
M81 is a satellite galaxy dubbed
Holmberg IX.

Studying the unexpectedly bright ultraviolet glow of this small
irregular galaxy
may help astronomers understand how the
many satellites
of our own Milky Way Galaxy developed.

visible through a small telescope, spans about 70,000
light years
and lies about 12 million light years away toward the
constellation of the Great Bear
(Ursa Major).

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