One of the true ‘bucket list’ objects for astrophotographers is the Eta Carina Nebula in the Southern Hemishpere. You really can’t see it from the U.S., certainly not well enough to think about taking a photo of it anyway.

So the very first item on my list of astrophoto targets for this trip was Carina, both because of it’s importance in the list, but also because it’s getting pretty low on the horizon in the west and you don’t have much more than two hours before it’s too low, and telescope guiding just turns to crap.

So that meant as soon as I had a stable working rig, I needed to get right to it. It ended up taking five consecutive night’s shooting sessions to get two hours of Hydrogen shots, and an hour each of red, green, and blue filtered shots resulting in five hours total exposure time.

Once I had what I needed I started processing while the telescope was shooting the next thing. It came together really quickly and I think this turned out extremely well!

The Eta Carina Nebula is the size of eight full moons, shoulder to shoulder in the sky. You can double-click on any image to see a larger version.

As I was in there de-noising, blurXterminating and all that I was really pleased at the amount and variety of detail in this object which is why it’s at the top of everyone’s list. Here are a couple closeups:

The upper left of the full frame image; that’s the Gem Cluster photobombing at the edge of the frame

So many cool dark structures throughout this object. The actual star Eta Carinae is in the upper left corner, blazing away near what white patch. Details on that star to follow.

In my earlier blog post about the Lagoon Nebula where I detail some of the processing steps you do with these images, I mentioned that sometimes you have to do things to minimize the visual impact of all those stars and that they can distract from your focusing on the nebula itself.

So here’s a version of it with no stars which also looks really cool!

Eta Carinae’s History

This star and it’s associated nebula are not without some drama. At one point in 1843 this star underwent a huge “Nova” event that temporarily made it the brightest object in the sky for a brief period of time as is considered to be one of the top supernova candidates for the near future, along with the bright star Betelgeuse in Orion.

The Carina Nebula lies 8,500 light-years away and is one of the largest diffuse nebulae known. It occupies a region of space 460 light years in diameter and is more than six times more distant than the famous Orion Nebula, but nevertheless appears both brighter and larger than the more famous M42.

Right now the Nebula is a hotbed of new star formation; as you can see there is plenty of raw gas and dust around to make new stars and solar systems. Gradually all of that will be depleted and over the next few million years all that will be left is a massive open cluster of new stars, with all the unconsumed loose gas getting blown away but the massive outpouring of energy from all these stars.

But in the meantime there are some notable things about the nebula and it’s various inhabitants.

• Eta Carina the star itself, is also a very rare type of star called a luminous hypergiant. It is estimated to be 400 million times brighter than the Sun.

• This nebula contains the brightest star we know of in the Milky Way, a Wolf-Rayet star, “WR 25” as a member of the star cluster Trumpler 16.

• Every year, stellar wind gusts blow away enough of the Carina Nebula’s mass to be equivalent to the size and mass of the planet Jupiter

• The Carina Nebula is one of the largest nebula in its class (which is “large, diffuse nebulae”) and one of the best to study for aspiring and established astronomers due to its brightness, location and diversity.

Now that I’ve bagged this, it’s back to the list to see what’s well-placed and interesting, I still have two months left here!

Bill Gwynne
aka Bill the Sky Guy