R136a1 (short for RMC 136a1) is one of the most massive and bright stars known, with a mass of 196 M and a luminosity of about 4.7 million L☉. It is also one of the hottest, with a temperature of around 46,000 K. It is a huge and very brilliant blue hypergiant star in the Milky Way’s satellite galaxy, the Large Magellanic Cloud (LMC).
It is a Wolf-Rayet star at the heart of R136, the huge NGC 2070 open cluster in the Tarantula Nebula (30 Doradus) of the huge Magellanic Cloud. At magnitude 7.25, the cluster can be viewed with binoculars or a small telescope in the extreme southern celestial hemisphere. R136a1 is 100 times fainter than the cluster and can only be seen with speckle interferometry.
Some key characteristics of R136a1:
- Distance – The distance to R136a1 cannot be determined directly, but is assumed to be at the same distance as the Large Magellanic Cloud at around 50 kiloparsecs or 163,000 light years.
- Mass: It is estimated to have a mass around 315 times that of our Sun, making it one of the most massive stars known. Such massive stars are relatively rare in the universe.
- Luminosity: This star is incredibly luminous, with a luminosity estimated to be over 7 million times that of the Sun. It radiates an immense amount of energy.
- Temperature: It is also extremely hot, with surface temperatures exceeding 50,000 degrees Celsius (90,000 degrees Fahrenheit).
- Size: The exact size of R136a1 is not well-determined, but it is likely to be several times the radius of the Sun due to its massive nature.
- Location: It is part of the R136 star cluster in the Tarantula Nebula (also known as 30 Doradus), which is one of the largest and most active regions of star formation in the Local Group of galaxies.
Discovery
A group of astronomers at Pretoria’s Radcliffe Observatory conducted systematic observations of the brightness and spectra of luminous stars in the Large Magellanic Cloud in 1960. Among the objects cataloged was RMC 136 (Radcliffe Observatory Magellanic Cloud catalog number 136), the central “star” of the Tarantula Nebula, which scientists believed was most likely a multiple-star system. Following studies revealed that R136 was in the middle of a massive region of ionized interstellar hydrogen known as a H II region, which was a hotspot of intense star formation in the neighborhood of the detected stars.
