Know (better) your neighbour: New HI structures in Messier 33 unveiled   by a multiple peak analysis of high-resolution 21-cm data
  In our quest to constrain the dynamical and structural properties of Local Group spirals from high-quality interferometric data, we have performed a neutral hydrogen survey in the direction of Messier 33. Here we present a few preliminary results from the survey and show the benefits of fitting the HI spectra by multiple peaks on constraining the structure of the Messier 33 disk. In particular we report on the discovery of new inner spiral-like and outer annular structures overlaying with the well-known main HI disk of Messier 33. Possible origins of the additional outer annular structure are presented. 
Laurent Chemin (Univ. de Bordeaux, CNRS), Claude Carignan (Univ. of   Cape Town), Tyler Foster (Brandon Univ.), Zacharie Sie...
astro-ph.CO astro-ph.GA