The Carina Nebula or Eta Carinae Nebula (catalogued as NGC 3372) is a large, complex area of bright and dark nebulosity in the constellation Carina, and is located in the Carina–Sagittarius Arm. The nebula is approximately 8,500 light-years (2,600 pc) from Earth. The nebula has within its boundaries the large Carina OB1 association and several related open clusters, including numerous O-type stars and several Wolf–Rayet stars. Carina OB1 encompasses the star clusters Trumpler 14 and Trumpler 16. Trumpler 14 is one of the youngest known star clusters at half a million years old. Trumpler 16 is the home of WR 25, currently the most luminous star known in our Milky Way galaxy, together with the less luminous but more massive and famous Eta Carinae star system and the O2 supergiant HD 93129A. Trumpler 15, Collinder 228, Collinder 232, NGC 3324, and NGC 3293 are also considered members of the association. NGC 3293 is the oldest and furthest from Trumpler 14, indicating sequential and ongoing star formation. The nebula is one of the largest diffuse nebulae in our skies. Although it is four times as large as and even brighter than the famous Orion Nebula, the Carina Nebula is much less well known due to its location in the southern sky. It was discovered by Nicolas-Louis de Lacaille in 1752 from the Cape of Good Hope. Eta Carinae is a highly luminous hypergiant star. Estimates of its mass range from 100 to 150 times the mass of the Sun, and its luminosity is about four million times that of the Sun. This object is currently the most massive star that can be studied in great detail, because of its location and size. Several other known stars may be more luminous and more massive, but data on them is far less robust. (Caveat: Since examples such as the Pistol Star have been demoted by improved data, one should be skeptical of most available lists of “most massive stars”. In 2006, Eta Carinae still had the highest confirmed luminosity, based on data across a broad range of wavelengths.) Stars with more than 80 times the mass of the Sun produce more than a million times as much light as the Sun. They are quite rare—only a few dozen in a galaxy as big as ours—and they flirt with disaster near the Eddington limit, i.e., the outward pressure of their radiation is almost strong enough to counteract gravity. Stars that are more than 120 solar masses exceed the theoretical Eddington limit, and their gravity is barely strong enough to hold in its radiation and gas, resulting in a possible supernova or hypernova in the near future. Eta Carinae’s effects on the nebula can be seen directly. Dark globules and some other less visible objects have tails pointing directly away from the massive star. The entire nebula would have looked very different before the Great Eruption in the 1840s surrounded Eta Carinae with dust, drastically reducing the amount of ultraviolet light it put into the nebula.

Telescope: Astro Physics 155EDF (TCC) f5.4
Mount: Astro Physics 1600GTO
Camera: FLI PL29050 / CFW2-7
Guider: Agena Starguide II / SBIG STi
Filters: Astrodon II 50mm 5nm Narrowband

H-alpha: 86×10 mins = 860 mins, OIII: 60×10 mins = 600 mins, SII: 60×10 mins = 600 mins

Total Imaging Time: 34h 20m

Data Imaged remotely over 9 nights during January, February, May & June 2021.
Imaged from Observatorio El Sauce, Chile, in partnership with Fred Espenak.
Data acquisition & Processing by David Churchill.

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