Omega Carinae

Omega Carinae, Latinized from ω Carinae, is a star in the constellation Carina. With a declination greater than 70 degrees south of the celestial equator, it is the most southerly of the bright stars of Carina (third-magnitude or brighter), and it is part of a southern asterism known as the Diamond Cross. This star has an apparent visual magnitude of 3.3 and is located at a distance of about 342 ly from Earth.

Properties
Omega Carinae has a stellar classification of B8 IIIe, which places it in the category of Be stars, that display emission lines of hydrogen their spectrum. Omega Carinae is a shell star, having a circumstellar disk of gas surrounding its equator. The luminosity class of III indicates it has evolved into a giant star, having exhausted the hydrogen at its core and left the main sequence. The effective temperature of $7.2$ in its outer envelope is what gives this star the blue-white hue that is characteristic of B-type stars.

This star is rotating rapidly with a projected rotational velocity of $11,630 K$, which gives a lower limit to the star's azimuthal velocity along the equator. The critical equatorial velocity, at which the star would begin to break up, is 320 km s−1. The star's axis of rotation is inclined by an estimated angle of 70.8° to the line of sight from the Earth.

In the next 7500 years, the south Celestial pole will pass close to this star (AD 5800) and then I Carinae.

In culture
In Chinese, 南船 (Nán Chuán), meaning Southern Boat, refers to an asterism consisting of ω Carinae, V337 Carinae, PP Carinae, θ Carinae and β Carinae. Consequently, ω Carinae itself is known as 南船四 (Nán Chuán sì, the Fourth Star of Southern Boat.)