R Coronae Australis and the Coronet Cluster in Corona Australis
May 2024 - Pictures of the Month
This is not the first time that this region of Corona Australis has featured on Picture of the Month. Martin Pugh provided an amateur view back in June 2018, but this time I've a reason for choosing an image from ESO’s Chilean telescopes, as you'll discover below.
The Coronet cluster in the image above is a young star forming region much like that in the Orion Nebula (Messier 42), visible in northern skies. It's embedded in the Corona Australis molecular cloud complex, and so comes complete the glowing gas and dust I enjoy so much. The Coronet lies about 170pc from us, whereas M 42 is about 412pc away, so due to its proximity it looks fairly sparse. It spans about 30 arc-minutes.
Of particular interest is the fact that it's full of stars that are less than two million years old, some much less, and of varying mass, providing the opportunity to observe stellar evolution in progress. Many of these stars are of course of variable brightness, and I want to draw attention to a couple in particular: the variables T and R Coronae Australis.
These two stars can be see near the centre of the image above, and they're embedded in a variable reflection nebula called NGC 6729. Below I've cropped into this nebula.
You can clearly see the fan-shaped nebula in the optical view above. R Coronae Australis sits at its apex with and T Coronae Australis to the right in the middle of the fan itself. What's interesting though is that ESO have imaged this region in the infrared in order to peek through all the obscuring dust. As you can see, doing so reveals many more young stars and far more internal detail of this reflection nebula.
In addition to valuable data, I think that these multi-wavelength studies provide some exciting new perspectives on well known objects that, so far, amateurs can't match. For those that agree, ESO have a fantastic slider view of the optical and IR versions covering the full field of the main image in this article.
James Whinfrey - Website Administrator.
