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Published online by Cambridge University Press: 04 August 2017
R136a is the luminous object in the core of the 30 Dor nebula in the LMC, embedded in the extremely young star cluster NGC 2070 with the most recent star forming event less 106 yr ago. R136a-1 (V = 11.08) lies in the center of this cluster. The companion or foreground star R136a-2 (ca. 1.2m fainter than R 136a-1) 0′.5 apart does not impair the dominating role of R136a-1. The light distribution is strongly peaked to the center of R136a and disagrees completely with Moffat and Seggewiss's (1983) description and their interpretation as a dense core of a cluster (Chu and Wolfire, 1983). This is strenghtened by the UV observations (Cassinelli et al. 1981, Feitzinger et al. 1983, Savage et al. 1983): the spatial spread function of the IUE satellite is dominated by an object of extremely small ultraviolet extent, less than that of a gaussian with 1′.5. Speckle observations (Meaburn, 1982; Weigelt, 1981), are discordant in the interpretation of the faint background, but concordant in revealing the existence of a small bright component, with an upper limit of the diameter < 0.02 pc. This is also found, with somewhat lower resolution, by Chu (1934).