银河系的邻居——微小却强硬

In the new ESO image, Barnard's Galaxy glows beneath a sea of foreground stars in the direction of the constellation（星座，星群） of Sagittarius (the Archer). At the relatively 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 galaxies that includes our home, the Milky Way. The nickname of NGC 6822 comes from its discoverer, the American astronomer Edward Emerson Barnard, who first spied this visually elusive（难懂的，难以捉摸的） cosmic islet（小岛） using a 125-millimetre aperture（孔，穴，缝隙） refractor in 1884. Astronomers obtained this latest portrait using the Wide Field Imager (WFI) attached to the 2.2-metre MPG/ESO telescope at ESO's La Silla Observatory in northern Chile. Even though Barnard's Galaxy lacks the majestic（宏伟的，庄严的） spiral arms and glowing, central bulge（膨胀） that grace its big galactic neighbours, the Milky Way, the Andromeda and the Triangulum galaxies, this dwarf 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 nebula. At the nebula's centre, a clutch of massive, scorching（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 ripples 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 dwarfish 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 random, blob-like forms from close encounters with or "digestion" 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 density of stars in galaxies is quite low, meaning that few stars physically collide during these cosmic dust-ups. Gravity's fatal attraction, however, can dramatically warp and scramble 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.