Conference Proceedings

# Galactic recycling: The HI ring around NGC 1533

E Ryan-Weber, R Webster, K Bekki, JL Rosenberg (ed.), ME Putman (ed.)

IGM/GALAXY CONNECTION: THE DISTRIBUTION OF BARYONS AT Z(EQUAL)0 | SPRINGER | Published : 2003

#### Abstract

We report the discovery of a new HI ring around the S0 galaxy NGC 1533. The ring orbits at a radius of 35 kpc, well outside the optical extent of the galaxy. We have conducted N-body/SPH numerical simulations to show this HI ring could be the merger remnant of a tidally destroyed galaxy. We find no optical component associated with the HI ring. However, observations hint at H-alpha emission associated with the SE part of the ring only. The H-alpha is in the form of a few very small isolated emission line regions. The large HI velocity dispersions (up to 30 km/s) and velocity gradients (up to 50 km/s/kpc) in this region indicate the H-alpha emission could be due to star formation triggered by..

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