How to View the Invisible Star CW Leonis

This article is going to discuss how you the amateur astronomer can view objects that are not giving off significant visible light, from your back garden.

CW Leonis, also known as IRC +10216, is one of these objects. At magnitude 18, it emits some faint visible light. But if you look at it in the infrared it shines roughly 10,000 times more brightly. 

This is because CW Leonis mostly emits its energy in the infrared wavelengths. This is likely due to the fact that CW Leonis is in the early stages of becoming a planetary nebula with most of its carbon-rich shell already blown off, forming a nebulous cloud.

It has been reported that the nebulous bubble around the star is just visible to some people with telescopes larger than 22 inches. However, no one has yet been able to see the star itself. The radiated energy is mainly released in the form of infrared radiation, so this would be expected.

So, in this article I am going to show you how to see such objects using near infrared astronomy. I did a general introduction into near infrared astronomy in this article.

Click to enlarge the CW Leonis star chart

At 310 light years away, CW Leonis is the closest carbon-rich star found so far. Carbon rich stars have more carbon content in their atmosphere as opposed to oxygen. As a result, the carbon atoms form carbon monoxide and absorb the remaining oxygen to form other carbon compounds that produce the ruby red colour of the star.

While CW Leonis was discovered using a 62-inch telescope back in the 1960s you can capture it through a telescope in your backyard.

It takes at least a four-inch telescope to see this, and ideally a monochrome camera because it is three times more sensitive to infrared light. You will also of course need an infrared pass filter. This blocks all other light except for infrared light allowing you to capture an infrared image. 

As CW Leonis is not visible visually, it is best to align your telescope and use GOTO functionality to move to the star. However, to do this visually you want to start at Regulus in the constellation Leo and then work along to nu Leonis then carry along in the same direction.

To see the difference between the infrared and visible shots of the star please watch the episode below, it also contains some pictures of the star field to help guide you to the correct location in Leo.

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