the biggest star WOH G64

2007 measurements using the Very Large Telescope (VLT) gave the star a bolometric luminosity of 282,000+40,000 −30,000 L☉ based on radiative transfer modelling of the surrounding torus, suggesting an initial mass of 25±5 M☉ and a radius around 1,730 R☉ based on the assumption of an effective temperature of 3,200 K. In 2009, Levesque calculated an effective temperature of 3,400±25 K by spectral fitting of the optical and near-UV SED. Adopting the Ohnaka luminosity with this new temperature gives a radius of 1,540 R☉ but with a margin of error of 5% or 77 R☉. Those physical parameters are consistent with the largest galactic red supergiants and hypergiants found elsewhere such as VY Canis Majoris and with theoretical models of the coolest, most luminous and largest possible cool supergiants (e.g. the Hayashi limit or the Humphreys–Davidson limit). Ignoring the effect of the dusty torus in redirecting infrared radiation, estimates of 1,970 - 1,990 R☉ based on a luminosity of 450,000+150,000 −120,000 L☉ and an effective temperature of 3,372 - 3,400 K have also been derived. Spectral features WOH G64 was discovered to be a prominent source of OH, H 2O, and SiO masers emission, which is typical of an OH/IR supergiant star. It shows an unusual spectrum of nebular emission; the hot gas is rich in nitrogen and has a radial velocity considerably more positive than that of the star. The stellar atmosphere is producing a strong silicate absorption band in mid-infrared wavelengths, accompanied a line emission due to highly excited carbon monoxide. Possible companion WOH G64 has a possible late O-type main-sequence star companion of a bolometric magnitude of −7. 5 or a luminosity of 100,000 L☉, which would make WOH G64 a binary star although there has been no confirmation of this observation and the intervening dust clouds makes the study of the star very difficult. See also B90, another red supergiant in the Large Magellanic Cloud VY Canis Majoris