A dwarf galaxy discovered close to the famous Sculptor Galaxy (NGC 253) by Australian astrophotographer Michael Sidonio has been studied in detail by the 8-metre Subaru Telescope in Hawaii. This fruitful collaboration between amateur and professional astronomers has revealed that the dwarf galaxy, now known as NGC 253-dw2, is being disrupted by the nearby giant spiral.
An international team of researchers have used the W. M. Keck Observatory to confirm the existence of the most diffuse class of galaxies known in the universe. These Ultra Diffuse Galaxies (UDGs) are nearly as wide as our own Milky Way galaxy — about 60,000 light-years — yet harbour only one percent as many stars.
A new study finds that elliptical galaxies maintain a remarkably constant circular speed out to large distances from their centres, in the same way that spiral galaxies do. In these very different types of galaxies, stars and dark matter somehow conspire to redistribute themselves to produce this effect, or does modified Newtonian dynamics offer an explanation?