The galaxy and its halo together contain several hundred billion times the mass of the sun; four times the mass of the Milky Way. It also whirls round extremely quickly, rotating at speeds of up to 1.8 million kilometers (1.1 million miles) per hour.
UGC 1810: Wildly Interacting Galaxy from Hubble : What’s happening to this spiral galaxy? Although details remain uncertain, it surely has to do with an ongoing battle with its smaller galactic neighbor. The featured galaxy is labelled UGC 1810 by itself, but together with its collisional partner is known as Arp 273. The overall shape of the UGC 1810 – in particular its blue outer ring – is likely a result of wild and violent gravitational interactions. This ring’s blue color is caused by massive stars that are blue hot and have formed only in the past few million years. The inner galaxy appears older, redder, and threaded with cool filamentary dust. A few bright stars appear well in the foreground, unrelated to UGC 1810, while several galaxies are visible well in the background. Arp 273 lies about 300 million light years away toward the constellation of Andromeda. Quite likely, UGC 1810 will devour its galactic sidekick over the next billion years and settle into a classic spiral form. via NASA
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. via NASA