A new infrared image of the Helix Nebula in the constellation Aquarius is shedding light on the enigmatic object's structure. Captured by the 4.1-meter VISTA telescope in northern Chile, the image, released online today by the European Southern Observatory, reveals solar-system-sized clumps and strands of hydrogen gas . These features, dubbed cometary knots because they typically point directly away from the star at the center of the nebula, can't be easily seen in visible light (inset). The main ring of the Helix Nebula is about 2 light-years across, about half the distance from our sun to the nearest star. The faint red halo that can be seen across much of the infrared image spans several light-years, the researchers estimate. Material in the nebula, which lies about 700 light-years from Earth, was shed from a sun-type star (blue dot denoted with arrow) during the final stages of its life. Eventually that star, which now shines fiercely in ultraviolet wavelengths, will evolve to become a white dwarf, a dense star about as massive as our sun yet only slightly larger than Earth.
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