A striking and beautiful Wolf-Rayet bubble

16″ at 228x: N57C = NGC 2020 lies approximately 100 light-years to the east of its neighbouring superbubble N57A, and it is without doubt the quintessential Wolf-Rayet bubble! Indeed, it is absolutely dumbfounding with and without a filter (best seen when the transparency is supreme). Without the filter, it is a fairly bright, distinctly glowing roundish bubble, slightly elongated SW-NE, 3’ x 2.5’, with a brighter inner filamentary ring surrounding a relatively large dark centre… with its mag 13 Wolf-Rayet star, Brey 48, lying in the dark centre. Brey 48 appears to lie in the centre in the entire bubble, although it lies north of the dark inner ring’s centre. A mag 12 star that lies on the southern edge of the bubble adds to the beauty of the scene. What a treat it is to see the stunning little glint of stellar light that has blown this glorious bubble! (In fact, when I observe a Wolf-Rayet bubble I can never decide which astounds me more – the sight of a bubble blown by a Wolf-Rayet star, or the Wolf-Rayet star that blew the bubble!)

The bubble responds fantastically to the UHC filter and shows some superb detail; the inner filamentary ring is very prominent, appearing sharply defined both against the dark centre and the fainter outer nebulosity. The outer nebulosity is beautifully uneven, full of very subtle and very delicate gradations of softly glowing light. The bubble’s edges gradually grow both fainter and more diffuse until disappearing into the dark sky. Truly gorgeous!! (And if we think this region of space is spectacular now, wait until Brey 48 goes supernova in a million years or less!)