A Planetary Nebula (N66) in the Large Magellanic Cloud
The NASA Hubble Space Telescope (HST) has imaged N66, a planetary nebula in the Large Magellanic Cloud (a satellite galaxy of our own Milky Way galaxy). The image was obtained at 10:41 p.m. EDT on June 26, 1991, using the European Space Agency's Faint Object Camera. This HST image is being presented on Thursday, January 16 at the 179th meeting of the American Astronomical Society in Atlanta, Georgia. This is the first time a planetary nebula has ever been seen so clearly in a galaxy beyond our own Milky Way. The nebula N66 is located 169,000 light-years away. The FOC image reveals complex structures and details as small as 0.08 light-years across (0.1 arcsecond resolution). None of these structures had ever been seen with ground-based telescopes. Although such an asymmetric structure had been anticipated based upon spectroscopic data taken with ground-based telescopes, the observed patterns are unprecedented. The FOC exposure lasted for just 540 seconds and was made through a filter which isolated the light of doubly ionized oxygen (5007 Angstroms). The image has been sharpened by computer image reconstruction, though all the structures are clearly evident in the raw image. The brightest part of the nebula has an angular diameter of about 2.4 arcseconds, which corresponds to a size of 1.9 light-years. The nebula was ejected by a luminous red giant star, which subsequently contracted to form a blue remnant star. Located at the center of the image, this remnant star ionizes the nebula, causing it to glow at visible and ultraviolet wavelengths. The star is destined to become a white dwarf. Individual lobes of the nebulosity are expanding from the center with velocities of up to one quarter million miles per hour (100 kilometers per second).