M101: The Pinwheel Galaxy
Explanation:
Why do many galaxies appear as
spirals?
A striking example is
M101,
shown above,
whose relatively close distance of about 27 million
light years allow it to be studied in some detail.
Recent evidence indicates that a
close gravitational interaction with a neighboring galaxy created
waves of high mass and condensed gas which
continue to orbit the galaxy center.
These
waves compress existing gas and cause star formation.
One result is that
M101, also called the
Pinwheel Galaxy, has several extremely
bright star-forming regions
(called
HII regions) spread across its spiral arms.
M101 is so large that its
immense gravity
distorts
smaller nearby galaxies.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
