UGC 12591: The Fastest Rotating Galaxy Known
Why does this galaxy spin so fast?
To start, even identifying which type of galaxy
UGC 12591 is difficult -- it has dark dust lanes like a spiral galaxy but a large diffuse bulge of stars like a
lenticular.
Surprisingly observations show that
UGC 12591
spins at about 480 km/sec, almost twice as fast as our
Milky Way, and the fastest rotation rate yet measured.
The mass needed to hold together a galaxy spinning this fast is several times the mass of our
Milky Way Galaxy.
Progenitor scenarios for
UGC 12591
include
slow growth by accreting ambient matter,
or rapid growth through a recent
galaxy collision or
collisions --
future observations may tell.
The light we see today from UGC 12591 left about
400 million years ago, when
trees were first developing on
Earth.