UGC 12591: The Fastest Rotating Galaxy Known
From NASA’s Astronomy Picture of the Week
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 light years ago, when trees were first developing on Earth.
