Nebulae
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The Heart of the Lobster: Pismis 24 and NGC 6357
This image is a high resolution narrowband close-up on Pismis 24 in the centre of the large nebula NGC 6357, also known as the 'Lobster' or 'War and Peace' nebula. The cluster and nebula lies 8000 light years away towards the constellation Scorpius.
In traditional RGB images this nebula appears intensely red with little colour variation (likely reddened by interstellar dust). But with data gathered in the specific emission bands of H-Alpha and Oxygen III the nebula takes on a much more colourful appearance. In addition, the image has been enhanced with broadband LRGB data to bring out more stars and their colours.
At the very centre of the nebula is a somewhat hollow cavity, home to the star cluster Pismis 24 containing some of the heaviest stars known. The intense ultraviolet radiation from these stars is slowly eroding the surrounding gas and dust away and shaping the delicate structures visible throughout the region. The heaviest of these stars, designated Pismis 24-1, was long thought to weigh some 200 to 300 solar masses, well in excess of the theoretical upper mass limit of about 150 solar masses for an individual star. But in 2006 high-resolution images taken with the Hubble Space Telescope showed that Pismis 24-1 is really two stars orbiting one another. Further to this, ground-based spectroscopic studies have revealed one of the stars to be yet a further tight binary. Still, these three stars are among the heaviest known in the Universe.
Link: High-resolution comparison of Pismis 24 with image from the Hubble Space Telescope.
Image details:
Date: May-July 2021
Exposure: H-Alpha OIII L R G B: 405:405:255:100:95:85, total 22 hours 25 mins @ -25C
Telescope: Homebuilt 12.5" f/4 Serrurier Truss Newtonian
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon 3nm Ha/OIII, LRGB E-Series Gen 2
Taken from my observatory in Auckland, New Zealand
