UGC 12591: The Fastest Rotating Galaxy Known
Image Credit: NASA, ESA, Hubble
Explanation: 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.
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