The central object of the → 30 Doradus nebula in the → Large Magellanic Cloud. Also known as HD 38268, it was thought to be a single star of several thousands → solar masses until → speckle interferometry techniques resolved it into a rich and compact star cluster. Recent high-resolution studies have shown that R136 contains 39 known O3 stars, which is more than known to be contained in the rest of the → Milky Way, → LMC, and → SMC combined. R136 is a prototype "super star cluster," with an estimated mass of 105 solar masses. Its most massive stars are less than 1-2 million yeas old, while its lower-mass stars formed 4-5 millions years ago.
The Radcliffe serial number 136 (Feast et al. 1960, MNRAS 121, 25).