R136a1 is the most and massive star, which is 300 times as massive as our sun.
The most massive known star in the sky is R136a1, a star more than 300 times as massive as our sun. And it's not alone in dwarfing Earth's dominant star.
RMC 136a1, usually abbreviated as R136a1, lies about 163,000 light-years from Earth in the Tarantula Nebula. This massive star lies outside our galaxy; it's part of the Large Magellanic Cloud, one of the Milky Way's satellite galaxies.
Astronomers working at the Radcliffe Observatory in South Africa first identified a star cluster in 1960, naming it RMC 136. When the Hubble Space Telescope examined the system, it found that the cluster was made up of more than 200 extremely bright stars; the most massive one was named RMC 136a1.