HD 93403

HD 93403 is a spectroscopic binary containing two highly luminous hot blue stars. It is 10,000 light years away in the Carina Nebula in the constellation Carina. It appears to have spectral type O5.5III, but this is composed of two spectra from a blue supergiant and blue main sequence star of spectral type O5.5I and O7V respectively. The two stars orbit every 15 days with a separation that varies from to. The binary is shedding mass at the high rate of 0.0005 per year.

HD 93403 exhibits the Struve-Sahade effect, where the strength of the spectral lines of the individual components varies during the orbit. It also has colliding stellar winds that produce variable x-ray and non-thermal radio emission.