OF HORSEHEADS AND UNICORNS

See some of the most massive stars ever discovered, a gorgeous horse head nebula formed by stellar winds and radiation and a light show deserving of Christmas in these pictures from NASA’s archive.

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NGC 6357: Stellar Wonderland


For reasons unknown, NGC 6357 is forming some of the most massive stars ever discovered. This complex wonderland of star formation consists of numerous filaments of dust and gas surrounding huge cavities of massive star clusters. The intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. The featured image includes not only visible light taken by the UKIRT Telescope in Hawaii (blue) as part of the SuperCosmos Sky Surveys, but infrared light from NASA's orbiting Spitzer Space Telescope (orange) and X-ray light from NASA's orbiting Chandra X-ray Observatory (pink). NGC 6357 spans about 100 light years and lies about 5,500 light years away toward the constellation of the Scorpion. Within 10 million years, the most massive stars currently seen in NGC 6357 will have exploded.

Photography: X-ray: NASA/CXC/PSU/L. Townsley et al; Optical: UKIRT; Infrared: NASA/JPL-Caltech

The Lagoon Nebula in High Definition


Stars are battling gas and dust in the Lagoon Nebula but the photographers are winning. Also known as M8, this photogenic nebula is visible even without binoculars towards the constellation of Sagittarius. The energetic processes of star formation create not only the colors but the chaos. The red-glowing gas results from high-energy starlight striking interstellar hydrogen gas. The dark dust filaments that lace M8 were created in the atmospheres of cool giant stars and in the debris from supernovae explosions. The light from M8 we see today left about 5,000 years ago. Light takes about 50 years to cross this section of M8. Data used to compose this image was taken with the wide-field camera OmegaCam of the ESO's VLT Survey Telescope (VST).

Photography: Data - ESO/INAF/R. Colombari/E. Recurt; Assembling & Processing: R. Colombari

Shell Game in the LMC


An alluring sight in southern skies, the Large Magellanic Cloud (LMC) is seen here through narrowband filters. The filters are designed to transmit only light emitted by ionized sulfur, hydrogen, and oxygen atoms. Ionized by energetic starlight, the atoms emit their characteristic light as electrons are recaptured and the atom transitions to a lower energy state. As a result, this false color image of the LMC seems covered with shell-shaped clouds of ionized gas surrounding massive, young stars. Sculpted by the strong stellar winds and ultraviolet radiation, the glowing clouds, dominated by emission from hydrogen, are known as H II (ionized hydrogen) regions. Itself composed of many overlapping shells, the Tarantula Nebula is the large star forming region at top center. A satellite of our Milky Way Galaxy, the LMC is about 15,000 light-years across and lies a mere 180,000 light-years away in the constellation Dorado.

Photography: John Gleason

The Magnificent Horsehead Nebula


Sculpted by stellar winds and radiation, a magnificent interstellar dust cloud by chance has assumed this recognizable shape. Fittingly named the Horsehead Nebula, it is some 1,500 light-years distant, embedded in the vast Orion cloud complex. About five light-years "tall", the dark cloud is cataloged as Barnard 33 and is visible only because its obscuring dust is silhouetted against the glowing red emission nebula IC 434. Stars are forming within the dark cloud. Contrasting blue reflection nebula NGC 2023, surrounding a hot, young star, is at the lower left. The gorgeous color image combines both narrowband and broadband images recorded using three different telescopes.

Photography: Marco Burali, Tiziano Capecchi, Marco Mancini (Osservatorio MTM)

Fox Fur, Unicorn, and Christmas Tree


Clouds of glowing hydrogen gas fill this colorful skyscape in the faint but fanciful constellation Monoceros, the Unicorn. A star forming region cataloged as NGC 2264, the complex jumble of cosmic gas and dust is about 2,700 light-years distant and mixes reddish emission nebulae excited by energetic light from newborn stars with dark interstellar dust clouds. Where the otherwise obscuring dust clouds lie close to the hot, young stars they also reflect starlight, forming blue reflection nebulae. The tall, telescopic mosaic image stands up about 3/4 degree or nearly 1.5 full moons, covering 40 light-years at the distance of NGC 2264. Its cast of cosmic characters includes the the Fox Fur Nebula, whose dusty, convoluted pelt lies just left of center, bright variable star S Monocerotis immersed in the blue-tinted haze right of the Fox Fur, and the Cone Nebula pointing down from the top of the frame. Of course, the stars of NGC 2264 are also known as the Christmas Tree star cluster. The triangular tree shape traced by the stars has its apex at the Cone Nebula. The tree's broader base is centered near S Monocerotis.

Photography: Michael Miller, Jimmy Walker