September Object of the Month: The Witch's Broom Nebula
Each month I chose one of my images and give you some background to what it is and how it was photographed. This month it is the Super nova remnant- The Witch's Broom.
What a great name!
A few thousand years BC a star more massive than our sun exploded violently, giving out enough light to have been visible for a few days from the Earth during daylight. This was a Super Nova explosion and ever since the remains have continued to travel at many thousands of miles per second across interstellar space. This is what is known as a Super Nova remnant. The colossal energy lights up its path as it collides with interstellar dust, creating a beautiful and stunning sight
The Witch’s Broom is estimated to be 1,400 light years away so the light has taken that time to travel across our galaxy to my camera. To place the object, it is outside of our Solar System, i.e. beyond all the planets that orbit the Sun, but inside our Galaxy, which is known as The Milky Way.
The Witch’s Broom is just one section of a large Super Nova Remnant with the entire structure being known as ‘The Veil Nebula’. The Witch’s Broom is the western section and also has a less interesting catalogue number of NGC 6960. It was first identified in the late 18th century by a British astronomer William Herschel, working from Bristol.
Although this is the death of a star it is also the beginning of life as contained within Super Novae is what goes to form Stars, Planets, you and me.
By the way, the bright star you see in the middle is unrelated to the nebula: It is in the foreground and catalogued as 52 Cygni.
Imaging The Witch’s Broom
This object is extremely faint from Earth and not much light is reaching the telescope and camera. In addition it emits light at specific wavelengths associated with certain ionized states of gases.
I use specialist filters which capture certain emissions from these gases, in this case Hydrogen Alpha (Ha), Oxygen III (OIII) and Sulphur II (SII). Using my telescope and cameras I captured 10’s of hours of data through these three filters over many nights. Each exposure was 20 minutes and at the end of each night I discard the sub optimal images, such as when the seeing conditions were not perfect or a satellite crossed the field of view. Over time I build up the data for each filter and eventually have enough to start the long process of calibration and processing.
During this process I want to extract the beautiful detail that exists buried within the raw data and at the same time make it look stunning for the Galaxy on Glass range.
In this section you can see some of the fine detail of the nebula.
In this section you can see the beautiful colours and how they accentuate the beauty within the nebula.
I use a convention to assign the colours developed for the Hubble Space telescope. This means that I assign the SII to the red channel, Ha to the green and OIII to the blue channel. You will see in this picture that there is a lot of blue, meaning the object is emitting a lot of light associated with the Oxygen. Using this convention shows rich blues and golds and the wispy details of the nebulosity.
I hope this gives you some insight into the beauty of this dramatic object. If you are interested in having this as a piece of wall art- either Framed Backlit, Frameless Acrylic or as a Fine art Print, then simply pop along to The Witch's Broom in Shop Images and you can purchase a limited edition piece right there.