NGC 1918 = LMC-N120C = LH 42

05 19 04.5 -69 38 56; Dor
V = 9.8; Size 7’x4′

24″ (4/5/08 – Magellan Observatory, Australia): this is a combination LMC cluster and nebula (contains the embedded SNR B0519-69.6) in the rich LMC central bar. At 200x. a striking double star (TDS 3145 = 11.6/11.8 at 9″) sits within the glow with a third star in a line. The brighter SW component is HD 35517 = Brey 22, a Wolf-Rayet binary. An additional 20 stars are resolved in the cluster (stellar association LH 42).

These stars are immersed in a diffuse nebulous glow that responds well to a UHC filter. The brightest section N120C is a patch just E of the double star, but nebulosity extends throughout the cluster as an elongated glow of ~5′ length. On images the nebulosity appears more like an arc or rim with some filamentary structure.

Notes: John Herschel discovered NGC 1918 between Nov 1836 and Mar 1837 with a 5-inch refractor and recorded it as #369 in his catalogue of “Stars, Nebulae and Clusters in the Nubecula Major.” Corwin notes that Herschel’s position falls between two bright knots near the supernova remnant.

Williamina Fleming classified the Wolf-Rayet star Brey 22 as an O-type star.