Carina Nebula

The Carina Nebula is a bright, large emission nebula surrounding the star Eta Carinae, located in the southern constellation Carina.

It is also sometimes called the Eta Carinae Nebula, the Grand Nebula, or the Great Nebula in Carina. The nebula’s designation in the New General Catalogue is NGC 3372. It is one of the largest diffuse nebulae known, one that contains several open star clusters.

The Carina Nebula is home to several notable objects: the Mystic Mountain, the Homunculus Nebula, and the Keyhole Nebula.

The Carina Nebula lies in the Carina-Sagittarius Arm of the Milky Way, at a distance between 6,500 and 10,000 light years from Earth. The estimated distance of the nebula is 7,500 light years.

NGC 3372 is exceptionally large, about four times the size of the Orion Nebula (Messier 42). It can easily be seen without binoculars even though it is about five times more distant than the famous nebula in Orion constellation.

Eta Carinae Nebula is not quite as well known as the Orion Nebula because it lies in the southern sky and can only be observed from equatorial and southern latitudes.
The nebula spans about 460 light years in diameter, covering an area of three degrees of the sky. It is one of the largest known star forming regions in the Milky Way.

X-ray images of the region reveal that the nebula has also been a site of multiple supernova explosions.

ETA CARINAE

Eta Carinae, the central star in the nebula, is a luminous supergiant, about four million times more luminous than the Sun, with 100 to 150 times the Sun’s mass. It is the most massive star that can be observed and studied in great detail thanks to its size and location. Eta Carinae is believed to be only 2 to 3 million years old.

The stellar wind inside the nebula surrounding the star blows off a mass equivalent to that of Jupiter every year, which means that Eta Carinae loses 100 billion times more mass than the Sun.

The star is currently in its final stages of life and will soon explode as a gigantic supernova or hypernova. This could happen within days or a million years from now, and it will likely result in the devastation of planets and starfields lying within a few thousand light years of the star.

Eta Carinae is believed to be part of a binary star system, which it shares with another supergiant. The other star is thought to be between 30 and 60 times more massive than the Sun. Every 5.5 years, the two massive stars make a closest approach, coming within 2 to 3 astronomical units of each other. As a result, their stellar winds collide and there is a huge outflow of radiation and light.

MYSTIC MOUNTAIN

The Mystic Mountain is a pillar of gas and dust located inside the Carina Nebula. It was photographed by the Hubble Space Telescope in February 2010, on the 20th anniversary of its launch. The images show a region with a shape resembling that of a mountain top surrounded by clouds.

The Mystic Mountain region is three light years in height and contains nascent stars which fire off jets of gas which can be seen streaming from the mountain peaks. The gas pillar is being slowly eroded by the light of the enormously large, massive young stars located above the pillar.

HOMUNCULUS NEBULA

The Homunculus Nebula is a much smaller region of nebulosity within NGC 3372, directly surrounding the star Eta Carinae.

The name of the smaller nebula means Little Man in Latin.

The Homunculus Nebula is believed to have been formed in the 1840s, when a powerful outburst briefly made the massive central star the second brightest star in the sky.

The event is known as Nova Carinae 1843, or the Great Eruption.

The outburst was also responsible for producing the two lobes the nebula is known for and a large, thin disk, all expanding at an approximate speed of 1 million kilometres per hour.

Prior to the outburst, Eta Carinae appeared as any other naked eye star, but then began to brighten and, by 1848, the star’s apparent magnitude reached its peak.

The star’s brightness then gradually faded again and, by 1880, Eta Carinae could no longer be seen without binoculars.

It is currently at the limit of naked eye visibility, but would appear much brighter if it were not surrounded by clouds of dust.

KEYHOLE NEBULA

The Keyhole Nebula is a dark nebula about seven light years in diameter.

It was named for its keyhole shape, for which it is known.

It lies silhouetted against the bright Carina Nebula in the background.

The Keyhole Nebula was named by the English mathematician and astronomer John Herschel in the 19th century.

It has its own designation in the New General Catalogue, NGC 3324.

CARINA NEBULA: FACTS AND LOCATION

The Carina Nebula was discovered by the French astronomer Nicolas Louis de Lacaille in 1751-52, who observed the southern constellations from the Cape of Good Hope in South Africa.

Astronomers John Herschel and James Dunlop, who also observed the southern skies, called the nebula the Eta Carinae Nebula or Eta Argus Nebula, referring to the former constellation Argo Navis, representing the ship of Jason and the Argonauts, which was split into several smaller constellations. Carina constellation represents the keel of the ship, while Vela represents the sails and Puppis constellation marks the stern. Herschel described the object as “The star η Argus, with the Great nebula about it.”

The Carina Nebula is home to several exceptionally bright and massive stars, including Eta Carinae and HD 93129A, and multiple O-type stars. It is known to contain at least a dozen stars with a mass at least 50 to 100 times than of the Sun.

NGC 3372 contains eight open clusters, including Collider 228, Trumpler 16 and Trumpler 14. Trumpler 14 is the youngest and most populated cluster in the group.

The first generation of newly formed stars in the nebula are believed to have condensed some three million years ago, igniting in the middle of a large hydrogen cloud. Radiation from these young stars shaped a bubble of hot gas, which has kept expanding ever since. The stellar winds and ultraviolet radiation within the region are compressing cold hydrogen, resulting in more new stars being formed inside the nebula.

The pillars of dust and gas within the Eta Carinae Nebula will be destroyed by the young stars over the next 100,000 years and all that will remain will be a new open star cluster.

Carina Nebula – NGC 3372
Type: Emission Nebula
Location: 10h 45m 08.5s (right ascension), -59°52’04” (declination)
Constellation: Carina
Visual magnitude: +1.0
Absolute magnitude: ~10.8
Distance: 6,500 – 10,000 light years
Radius: ~100 pc
Mass: 900,000 solar masses
Designations: Carina Nebula, Eta Carinae Nebula, Grand Nebula, Great Nebula in Carina, NGC 3372, Caldwell 92, GC 2197, ESO 128-EN013