HD 93205, or V560 Carinae, is a binary stellar system, in the

Carina Nebula The Carina Nebula or Eta Carinae Nebula (catalogued as NGC 3372; also known as the Great Carina Nebula) is a large, complex area of bright and dark nebulosity in the constellation Carina, located in the Carina–Sagittarius Arm of the Milky Wa ...

(NGC 3372) in the constellation Carina. It consists of two massive O-stars that revolve around each other in 6

day A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours, 1440 minutes, or 86,400 seconds. In everyday life, the word "day" often refers to a solar day, which is the length between two so ...

s. The more massive member of the pair is an O3.5 main sequence star. The spectrum shows some ionised nitrogen and helium emission lines, indicating some mixing of fusion products to the surface and a strong

stellar wind A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. D ...

. 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 300 km/s and is considered to be a relativistic binary, which causes the apses of the orbit to change in a predictable way. The closeness of the two stars causes them to become deformed, and this means that the observed brightness of the system varies slightly every six days during its orbit. The total amplitude of the variation is only 0.02 magnitudes. It is generally considered as a member of the open cluster Trumpler 16. Among its neighbors are some of the most massive and luminous stars in the galaxy, like Eta Carinae, HD 93250 and the binary

HD 93129 HD 93129 is a triple star system in the Carina Nebula, with all three components being hot O class stars amongst the most luminous stars in the Milky Way. It is the dominant member of the Trumpler 14 star cluster, a young star cluster w ...

. It lies five arc-minutes from Eta Carinae.

References

{{DEFAULTSORT:HD 93205 Carina Nebula O-type main-sequence stars Spectroscopic binaries Carinae, V560 Durchmusterung objects 093205 Carina (constellation) Emission-line stars Rotating ellipsoidal variables