R99 [SEP] constellation
R99
R99 (HD 269445) is a star in the Large Magellanic Cloud in the constellation Dorado. It is classified as a possible luminous blue variable and is one of the most luminous stars known.
R99 has a peculiar spectrum that has been described as OBf:pe, "unclassifiable", peculiar WN10, "similar to the unusual LBV HD 5980", "unique", and Ofpe/WN9. The Ofpe/WN9 type remains even though other stars of this type have been reclassified to types between WN9
of R99 may be significantly different to most WR stars and LBVs. The normal temperature-stratified WR wind is accelerated to terminal velocity, causing lines of different ionisation levels of Helium to be created at different distances from the star. This does not seem to apply to R99. Significant polarisation of the spectrum continuum is also seen, suggesting an asymmetric wind. This has not been observed in other WR stars.
R99 shows brightness variations of about 0.3 magnitude over a period of decades, and smaller amplitudes with the strongest periods