Journal Article

Lopsided galaxies: the case of NGC 891

M. Mapelli, B. Moore and J. Bland-Hawthorn

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 388, issue 2, pages 697-708
Published in print August 2008 | ISSN: 0035-8711
Published online July 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13421.x
Lopsided galaxies: the case of NGC 891

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It has been known for a long time that a large fraction of disc galaxies are lopsided. We simulate three different mechanisms that can induce lopsidedness: flyby interactions, gas accretion from cosmological filaments and ram pressure from the intergalactic medium. Comparing the morphologies, H i spectrum, kinematics and m= 1 Fourier components, we find that all of these mechanisms can induce lopsidedness in galaxies, although in different degrees and with observable consequences. The time-scale over which lopsidedness persists suggests that flybys can contribute to ∼20 per cent of lopsided galaxies. We focus our detailed comparison on the case of NGC 891, a lopsided, edge-on galaxy with a nearby companion (UGC 1807). We find that the main properties of NGC 891 (morphology, H i spectrum, rotation curve, existence of a gaseous filament pointing towards UGC 1807) favour a flyby event for the origin of lopsidedness in this galaxy.

Keywords: methods: N-body simulations; galaxies: individual: NGC 891; galaxies: interactions; galaxies: kinematics and dynamics

Journal Article.  8169 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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