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| NGC 2244, Open Star cluster in the Rosette Nebula located in the constellation Monoceros the Unicorn. Data credit: COAST robotic telescope - SHO filters - blended Sll and Ha for luminance, telescope org. Open Observatories, Open University. Image Credit: Kurt Thrust at the JPO. |
" The Essex based astroimager, Nik Szymanek , has been writing an interesting series of articles in the magazine Astronomy Now, showcasing the ways in which SHO palette images may be processed using the Sll and Ha data as a synthetic luminance layer. I was much intrigued with this idea and and wondered if the Rosette Nebula might respond well to using a blended Sll and Ha synthetic luminance layer. The particular blend I used accentuated Sll (ionised sulphur}over and above the Ha (Hydrogen alpha) content. I believe this image processing method has made for the more dramatic photograph above" - Kurt Thrust current Director of the Jodrell Plank Observatory.
The Rosette Nebula; Seestar S30 with Dual Band nebula filter,
flipped vertically to match orientation with the top detail image
Processed to emphasise the H alpha component of the image.
Image Credit: Pip Stakkert at the JPO
| The Rosette Nebula; Seestar S30 with Dual Band nebula filter, flipped vertically to match orientation with the other images . Processed to emphasise the 3 dimensional nature of the nebula with reduced emphasis on the H alpha component of the image. Image Credit: Pip Stakkert at the JPO |
A Brief Report on the Open Cluster NGC 2244 and Ionised Gas in the Rosette Nebula
The open star cluster NGC 2244 is located at the centre of the Rosette Nebula (Caldwell 49), a large H II region in the constellation Monoceros, at an approximate distance of 1.5–1.6 kiloparsecs (about 5,000 light-years) from the Sun. The cluster has an estimated age of 2–6 million years and is composed primarily of young, massive O- and B-type stars. These hot, luminous members are the principal sources of the nebula’s ionisation and play a dominant role in shaping its morphology through intense ultraviolet radiation and stellar winds.
The energetic radiation field of NGC 2244 drives a strong ionisation front, producing extensive emission in the H α (656.3 nm) recombination line of hydrogen, characteristic of classical H II regions. The nebula’s interior exhibits strong [O III] (495.9 and 500.7 nm) emission, arising from doubly ionised oxygen in regions of higher excitation closer to the cluster core. In contrast, [S II] (671.6 and 673.1 nm) lines are more prevalent along the periphery of the nebula and in dense ionisation fronts, where lower excitation and partially ionised zones are found.
The spatial distribution of these emission lines delineates the stratified ionisation structure typical of massive star-forming regions: [O III] tracing the hottest, most highly ionised gas; H α marking the main ionised hydrogen volume; and [S II] outlining the transition to neutral material. Together, these diagnostics reveal the ongoing interaction between the cluster’s massive stars and their natal molecular cloud, providing a detailed view of stellar feedback processes in early cluster evolution. - Professor G.P.T Chat visiting astrophysicist at the Jodrell Plank Observatory.
