In the new ESO image, Barnard's Galaxy1 glows beneath a sea of foreground stars in the direction of the constellation2(星座,星群) of Sagittarius (the Archer). At the relatively3 close distance of about 1.6 million light-years, Barnard's Galaxy is a member of the Local Group (ESO 11/96), the archipelago(群岛) of galaxies4 that includes our home, the Milky5 Way. The nickname of NGC 6822 comes from its discoverer, the American astronomer6 Edward Emerson Barnard, who first spied this visually elusive7(难懂的,难以捉摸的) cosmic islet(小岛) using a 125-millimetre aperture8(孔,穴,缝隙) refractor in 1884. Astronomers9 obtained this latest portrait using the Wide Field Imager (WFI) attached to the 2.2-metre MPG/ESO telescope at ESO's La Silla Observatory10 in northern Chile. Even though Barnard's Galaxy lacks the majestic11(宏伟的,庄严的) spiral arms and glowing, central bulge12(膨胀) that grace its big galactic neighbours, the Milky Way, the Andromeda and the Triangulum galaxies, this dwarf13 galaxy(矮星系) has no shortage of stellar splendour(光彩,显赫) and pyrotechnics(烟火). Reddish nebulae(星云) in this image reveal regions of active star formation, where young, hot stars heat up nearby gas clouds. Also prominent in the upper left of this new image is a striking bubble-shaped nebula14. At the nebula's centre, a clutch of massive, scorching15(灼热的) stars send waves of matter smashing into the surrounding interstellar(星际的) material, generating a glowing structure that appears ring-like from our perspective. Other similar ripples16 of heated matter thrown out by feisty(易怒的,活跃的) young stars are dotted across Barnard's Galaxy.
At only about a tenth of the Milky Way's size, Barnard's Galaxy fits its dwarfish17 classification. All told, it contains about 10 million stars — a far cry from the Milky Way's estimated 400 billion. In the Local Group, as elsewhere in the Universe, however, dwarf galaxies outnumber their larger, shapelier cousins.
Irregular dwarf galaxies like Barnard's Galaxy get their random18, blob-like forms from close encounters with or "digestion19" by other galaxies. Like everything else in the Universe, galaxies are in motion, and they often make close passes or even go through one another. The density20 of stars in galaxies is quite low, meaning that few stars physically21 collide during these cosmic dust-ups. Gravity's fatal attraction, however, can dramatically warp22 and scramble23 the shapes of the passing or crashing galaxies. Whole bunches of stars are pulled or flung from their galactic(星系的) home, in turn forming irregularly shaped dwarf galaxies like NGC 6822.