Study of the interacting system NGC 6845

Abstract

We present optical spectroscopy, B, V , R, and I CCD photometry, and VLA neutral hydrogen observations of the interacting quartet NGC 6845, also know as Klemola 30. NGC 6845 A, the dominant component, sports a broad and bright tidal bridge and a faint tidal tail, which bifurcates. The tidal bridge has a B[I color bluer than that of the inner disk of NGC 6845 A. Five strong condensations, identified as H II regions brighter than the brightest one known in our Galaxy, are found along the tidal bridge, with the two most luminous located at the bridge tip. Two giant H II regions, comparable to 30 Dor, are located where the tidal bridge and the tidal tail join the disk of NGC 6845 A.