Taking advantage of a little unscheduled observing time on one of their telescopes, researchers at the European Southern Observatory turned the instrument on a ghostly green cloud in the Southern Hemisphere constellation Scutum ("The Shield"). The image that they gleaned is the best view yet of this little-known celestial bauble, the researchers report online today. The mysterious object, dubbed IC 1295, is a planetary nebula, an expanding cloud of debris cast off by a dying star. IC 1295 lies about 3300 light-years from Earth and consists of several shells of material, each belched from the central star as it entered the final phases of its life. The shells glow green because of the predominance of ionized oxygen, whose electrons have been stripped from the fluorescing atoms by the intense ultraviolet radiation now streaming from the remnant of the parent star (blue-white dot denoted by arrow). Over the next few billion years, the central star will cool down to become a faint white dwarf, just as all stars between one and eight times the size of our sun eventually do. Planetary nebulae, which typically last about 10,000 years, have nothing to do with planets in our solar system: They only gained that name because the first few to be discovered, late in the 18th century, were fuzzy blobs that looked similar to the gas giant Uranus—at least to the telescopes of the day.
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