Also known as the Great Nebula in Carina, the Eta Carinae Nebula, or NGC 3372, it is one of the largest diffuse nebulae that has within its boundaries several related open clusters of stars. The Chandra X-Ray Observatory has detected more than 14,000 stars in the region. Although it is some four times as large and even brighter than the famous Orion Nebula, the Carina Nebula is much less well known, due to its location in the southern sky.
The nebula lies at an estimated 8,800 light years from Earth in the constellation of Carina, and is located in the Carina–Sagittarius Arm. Nicolas Louis de Lacaille discovered it in 1752 from the Cape of Good Hope.
It contains two of the most massive and luminous stars in our Milky Way galaxy, Eta Carinae and HD 93129A. The nebula itself spans some 460 light years across, about 7 times the size of the Orion Nebula. Eta Carinae (the brightest star in this image) is the most luminous star known in the Galaxy, and has most likely a mass over 100 times that of the Sun. Its luminosity is about four million times that of the Sun. It is the closest example of a luminous blue variable – the last phase in the life of a very massive star before it explodes in a fiery supernova.
Eta Carinae’s effects on the nebula can be seen directly; the dark globules in the image and some other less visible objects have tails pointing directly away from the massive star. Eta Carinae is surrounded by an expanding bipolar cloud of dust and gas known as the Homunculus (little man in Latin), which astronomers believe was expelled from the star during a great outburst seen in 1843. The explosion produced two lobes and a large, thin equatorial disk, all moving outward at about 1 million kilometers per hour.
A portion of the Carina Nebula is known as the Keyhole (left of centre in the shape of an ear with a hole in it), a name introduced by John Herschel in the 19th century. The Keyhole Nebula is a much smaller and darker cloud of cold molecules and dust within the Carina Nebula, containing bright filaments of hot, fluorescing gas, silhouetted against the much brighter background nebula. The diameter of the Keyhole structure is approximately 7 light years. The Keyhole does not have its own NGC designation.
The “Mystic Mountain” is an image of a dust–gas pillar in the Carina Nebula taken by the Hubble Space Telescope. The pillar measures three light years in height, consisting of nascent stars inside the pillar fire of gas jets, that stream from towering peaks. The top of the pillar of cool hydrogen is being worn away by the radiation of nearby stars, while stars within the pillar unleash jets of gas that stream from the peaks.
The Chandra’s X-ray vision provides strong evidence that massive stars have self-destructed in this nearby star-forming region. Firstly, there is an observed deficit of bright X-ray sources in the area known as Trumpler 15, suggesting that some of the massive stars in this cluster were already destroyed in supernova explosions. Trumpler 15 is located in the northern part of the image and is one of ten star clusters in the Carina complex. The bright star groupings close to the center of the picture are the two youngest clusters of stars called Trumpler 14 and Trumpler 16.
Sources: Hubble, NASA, Space, Wikipedia.