HE1327-2326. Image: Subaru Telescope.
HE1327-2326 is the most metal-poor star known; it has a metallicity of -5.6, which means it has an iron content 300,000 times less than that of the Sun and is composed almost purely of hydrogen and helium. On this basis, it is also the oldest known star in the Milky Way Galaxy with an estimated age of more than 12 billion years. HE1327-2326 lies in the constellation Hydra (RA 13h 30m 06s; Dec. -23° 41' 54") at a distance of about 4,000 light-years in the sparsely populated halo region of old objects that surrounds the Galaxy. It has a visual magnitude of 13.5.
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