Floating serenely against the colourful, epic backdrop of IC 2944 in Centaurus are Thackeray’s globules, named after the British astronomer who first described them in this object 1950. Globules of this type are more generally known as Bok globules after Bart Bok and Edith Reilly who published on them in 1947 [Bok, B.J. & Reilly, E.F. (1947). Small Dark Nebulae. Astrophysical journal, 105, 255-257]. On this basis, perhaps they should be more correctly termed Bok-Reilly globules. Their paper described these clouds as being "similar to insect's cocoons" that were undergoing gravitational collapse to form new stars and star clusters.
Bok-Reilly globules are small isolated dark interstellar clouds of very cold gas and dust that are sufficiently thick to be nearly totally opaque to visible light, and although star formation within their interiors was hypothesised by Bok and Reilly, it has only been through relatively recent use of infrared, submillimeter, and millimeter imaging techniques that this has been verified.
This deep image of IC 2944 represents almost 25 hrs of total exposure using hydrogen alpha, OIII and SII filters and reveals lots of fine scale structure in the heart of the nebula behind the tiny Bok globules. Also captured in this image is the very cute - but unrelated to IC 2944 - planetary nebula PK294-0.1 shown in the top right.
600s exposures, OIII x 49, H-a x 54, SII x 45 = 24hrs 40mins. Takahashi TOA130 with 67 flattener giving f7.6 at 1000mm focal length, ASI6200 MM Pro, Chroma filters, AP1200GTO CP4. Images made over multiple nights in April 2024 from my solar-powered observatory at Star Field, S. Wairarapa, NZ
