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RMC 136a1 (usually abbreviated to R136a1) is a Wolf-Rayet star located at the center of R136, the central condensation of stars of the large NGC 2070 open cluster in the Tarantula Nebula. It lies at a distance of about 50 kiloparsecs (163,000 light-years) in the Large Magellanic Cloud. It has the highest mass and luminosity of any known star, at 265 and 8.7 million , and also one of the hottest at over 50,000 K. ==Discovery== In 1960, a group of astronomers working at the Radcliffe Observatory in Pretoria made systematic measurements of the brightness and spectra of bright stars in the Large Magellanic Cloud. Among the objects cataloged was RMC 136, (Radcliffe observatory Magellanic Cloud catalog number 136) the central "star" of the Tarantula Nebula. Subsequent observations showed that R136 was located in the center of a giant H II region that was a center of intense star formation in the immediate vicinity of the observed stars. In 1979, ESO's 3.6 meter telescope was used to resolve R136 into three components; R136a, R136b, and R136c. The exact nature of R136a was unclear and a subject of intense discussion. Estimates that the brightness of the central region would require as many as 100 hot O class stars within half a parsec at the centre of the cluster led to speculation that a star 3,000 times the mass of the sun was the more likely explanation. The first demonstration that R136a was a star cluster was provided by Weigelt and Beier in 1985. Using the speckle interferometry technique, R136a was shown to be made up of 8 stars within 1 arcsecond at the centre of the cluster, with R136a1 being the brightest. Final confirmation of the nature of R136a came after the launch of the Hubble Space Telescope. Its WFPC resolved R136a into at least 12 components and showed that R136 contained over 200 highly luminous stars.〔 The more advanced WFPC2 allowed the study of 46 massive luminous stars within half a parsec of R136a and over 3,000 stars within a 4.7 pc radius. It was only in 2010 that the star was recognized as the most massive and luminous star known. Previous estimates had placed the luminosity as low as . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「R136a1」の詳細全文を読む スポンサード リンク
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