Polar Ring Galaxy NGC 4650A
Explanation:
NGC 4650A appears to be two galaxies in one.
A rare type of galaxy known as a
Polar Ring,
NGC 4650A is composed of an
old central group of stars and a
young ring of stars rotating farther out.
Both components are clearly visible in this
featured photograph by the
Hubble Space Telescope.
What creates
Polar Ring Galaxies is still being researched,
but a leading theory is the
collision
of two distinct galaxies in the distant past.
Polar Ring Galaxies
allow astronomers to estimate the amount of
dark matter in galaxies by measuring the
rotation rate of the highly extended ring.
An unknown type of
dark matter is implied because the
ring typically
rotates too fast to be held together by
only the visible stars.
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.
