- Chris Baker
Object of the month - The Eta Carinae nebula
The Eta Carinae Nebula
About Eta Carinae
The Eta carinae nebula, also known as the grand nebula, is a massive cloud of nebulosity, containing bright and dark nebulae. To put it’s size in perspective, it is over four times the size and considerably brighter than the more well-known Orion nebula.
The nebula is located in the southern hemisphere constellation of Carina and is estimated to be 8,500 light years away.
Contained within the cloud are numerous star forming regions and young stars, some as young as 500,000 years. This makes them some of the youngest stars discovered in the Milky Way.
The star at the centre of the nebula is one of the most luminous stars discovered in the Milky Way
The Eta Carinae nebula was discovered by Nicolas-Louis de Lacaille in 1752 from the Cape of Good Hope.
Also contained within this image is a smaller and less well-known nebula – the Gabriela Mistral nebula. You can see this at the top left of my image.
The Gabriela Mistral nebula is an emission nebula located about 7,200 light-years away at the northwest corner of the Carina Nebula.
Gas and dust is creating new extremely massive and very hot young stars. The intense radiation from these hot young stars causes the gas cloud to glow and has carved out a cavity in the surrounding gas and dust.
The dark patches in the image are regions where veils of dust block out the light from the background glowing gas.
Astronomers often attach nicknames to nebulae based on their shape. The edge of the wall of gas and dust bears some sort of resemblance to a human face in profile, with the bump in the centre corresponding to a nose. Hence it’s name: Gabriela Mistral nebula, after the Nobel Prize-winning poet from Chile.
See the resemblance?
No, nor do I!
Imaging Eta Carinae
This is my first image from the Heaven’s Mirror observatory in Australia. This was established to compliment my equipment in Spain in July 2021. I now have the whole southern hemisphere to view and this had to be the first object to go after!
An image such as this requires many tens of hours of exposure to get the detail you can see here. In this case I imaged through a range of filters for over 20 hours. To build up the data I take what are called ‘sub frames’ or images of a shorter duration, which I can later stack together using astronomy software. The sub frames for Eta carinae were 20 minutes each. After a night of imaging I review the results frame by frame and reject those that are not perfect. (Imperfections are typically caused by poor seeing, aircraft or satellites passing across the frame or software or hardware issues). I ended up with 20 hours of perfect sub frames for the nebula.
I used three filters, each designed to capture the emissions of certain ionized gasses. These are Sulphur II, Oxygen III and Hydrogen Alpha.
The next stage is a calibration routine which eliminates the unwanted artefacts caused by long duration exposures. Finally, I spend a long time processing the data to bring out the beauty and detail.
In this case it is one of the most beautiful images I have captured and created.
If you would like to see all the options for Eta Carinae simply click HERE