Evidence for a Large Stellar Bar in the LSB Galaxy UGC 7321
Abstract
Late-type spiral galaxies are thought to be the dynamically simplest type of disk galaxies and our understanding of their properties plays a key role in the galaxy formation and evolution scenarios. The low surface brightness (LSB) galaxy UGC 7321, a nearby, isolated, ``superthin'' edge-on galaxy, is an ideal object to study those purely disk dominated bulge-less galaxies. Although late type spirals are believed to exhibit the simplest possible structure, even prior observations showed deviations from a pure single component exponential disk in the case of UGC 7321. We present for the first time photometric evidence for peanut-shaped outer isophotes from a deep optical (R-band) image of UGC 7321. Observations and dynamical modeling suggest that boxy/peanut-shaped (b/p) bulges in general form through the buckling instability in bars of the parent galaxy disks. Together with recent HI observations supporting the presence of a stellar bar in UGC 7321 this could be the earliest known case of the buckling process during the evolutionary life of a LSB galaxy, whereby material in the disk-bar has started to be pumped up above the disk, but a genuine bulge has not yet formed.
Cite
@article{arxiv.astro-ph/0307315,
title = {Evidence for a Large Stellar Bar in the LSB Galaxy UGC 7321},
author = {M. Pohlen and M. Balcells and R. Luetticke and R. -J. Dettmar},
journal= {arXiv preprint arXiv:astro-ph/0307315},
year = {2009}
}
Comments
LaTeX, 6 pages, 4 figures, accepted to be published in A&A