TWO PLANES OF SATELLITES IN THE CENTAURUS A GROUP

Abstract

Tip of the red giant branch measurements based on Hubble Space Telescope and\nground-based imaging have resulted in accurate distances to 29 galaxies in the\nnearby Centaurus A Group. All but two of the 29 galaxies lie in either of two\nthin planes roughly parallel with the supergalactic equator. The planes are\nonly slightly tilted from the line-of-sight, leaving little ambiguity regarding\nthe morphology of the structure. The planes have characteristic r.m.s. long\naxis dimensions of ~300 kpc and short axis dimensions of ~60 kpc, hence axial\nratios ~0.2, and are separated in the short axis direction by 303 kpc.\n