given as O5, O6/7, O4, and O3. It has sometimes been classified as a main sequence star and sometimes as a giant star. The Galactic O-Star Spectroscopic Survey has used it as the standard star for the newly created O4 subgiant spectral type. HD 93205 HD 93205 is a binary system of two large stars. The more massive member of the pair is an O3.5 main sequence star. The spectrum shows some ionized nitrogen and helium emission lines, indicating some mixing of fusion products to the surface and a strong stellar wind. The mass calculated from apsidal motion of the orbits is . This is somewhat lower than expected from evolutionary modelling of a star with its observed parameters. The less massive member is an O8 main sequence star of approximately . It moves in its orbit at a speed of over and is considered to be a relativistic binary, which causes the apses of the orbit to change in a predictable way. Catalogued open clusters in Carina Nebula , there are eight known open clusters in the Carina Nebula: Bochum 10 (Bo 10) Bochum 11 (Bo 11) Collinder 228 (Cr 228) Collinder 232 (Cr 232) Collinder 234 (Cr 234) Trumpler 14 (Tr 14, Cr 230) Trumpler 15 (Tr 15, Cr 231) Trumpler 16 (Tr 16, Cr 233) Annotated map Gallery See also Tarantula Nebula References External links Carina Nebula at SEDS.org Carina Nebula at Atlas of the Universe Carina Nebula at Constellation Guide Carina (constellation) Carina–Sagittarius Arm H II regions 3372 092 Articles containing video clips 17520125 Star-forming regions