Carina Nebula

"We are borne of Carina's cradle. This nebula is our home. And we will defend it to our last."

- Eccclisarch Kanans Uwita

The Carina Nebula, also known as the Grand Nebula, Great Nebula in Carina, and Eta Carinae Nebula is a H II region diffuse-nebula with a diameter between 230 to 460 lightyears across, located within the Carina–Sagittarius Arm of the Milky Way Galaxy. Home to the ankoran homeworld, and the seat of the Ankoran Covenant’s political power, the Carina Nebula is one of the most heavily-defended regions of the Milky Way Galaxy.

The Carina Nebula is home to some of the largest and most luminous stars in the Milky Way, including several O-Class Hypergiant stars, multiple Wolf–Rayet Stars, the Eta Carinae binary system, and the Divine Twins, (known to human astronomers as ‘WR25’), the most luminous star system in the entire Milky Way galaxy, a Wolf–Rayet star and A-Class main-sequence star. The nebula’s youngest star cluster is only half-a-million years old (known to human astronomers as the Trumpler 14 open cluster).

Several of these supermassive stars are expected to go supernova in the somewhat near future, and evacuation plans for several systems have been on standby for centuries, waiting for the signs of the approach of these stars' deaths.

Eta Carinae
Eta Carinae is a major binary star system in the Carina Nebula, home to two hypergiant stars. The primary, larger star in the Eta Carinae system is a peculiar star similar to a luminous blue variable, once weighing over 250 solar masses. It has, however, shrunk by 30 solar masses during a period known as the Great Eruption which occurred in 6393 BC. During this time, it became the second most luminous star in the Milky Way Galaxy, before dimming considerably. A second eruption occurred 36 years later, in 6429 BC, in which the system became the 6th most luminous star system in the galaxy. The primary star is expected to go supernova within the immediate astronomical future, much to the concern of the Ankoran Covenant, who has already prepared evacuation plans for Eta Carinae and surrounding systems.

The secondary star is a hot and also highly luminous O-class hypergiant star, although much less active. It has garnered little scientific interest from the races of the galaxy, overshadowed by its sibling.

The system is heavily obscured by the Homunculus Nebula, material ejected from the primary during the Great Eruption. It is a member of the Trumpler 16 open cluster within the much larger Carina Nebula.

Homunculus Nebula
The Homunculus Nebula is a bipolar emission and reflection nebula surrounding the massive star system Eta Carinae, embedded within, and part of, the much larger Carina Nebula. Ejected in an enormous outburst in 1841 which briefly made Eta Carinae the second-brightest star in the sky, the Homunculus Nebula is a small H II region, with gas shocked into ionised and excited states.

The Ankoran Covenant uses the highly energetic, ionised gasses to hide top-secret military stations, black sites, and other unacknowledged facilities. It is speculated a total of 21 programs are being secretly operated within the nebula, though no actual evidence of such rumours having merit exists; the Covenant denies any and all accusations of hosting black sites in the Homunculus Nebula.

The nebula also absorbs much of the light from the extremely luminous central stellar system and re-radiates it as infrared (IR). It is the brightest object in the sky at mid-IR wavelengths.

Keyhole Nebula
The Keyhole, or Keyhole Nebula, is a small dark cloud of cold molecules and dust within the Carina Nebula, containing bright filaments of hot, fluorescing gas, silhouetted against the much brighter background nebula. Named for its distinctive keyhole shape when viewed from the correct angle, the appearance of the region has changed significantly over the past thousand years, due to changes in the ionising radiation from Eta Carinae.

The Keyhole is home to the Carina Foundation’s headquarters on the planet Sultae.

Trivia
The Carina Nebula is a non-fictional location in the Milky Way Galaxy.