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.

LaTeX, 6 pages, 4 figures, accepted to be published in A&A

References in corpus (4)

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• The dark matter halo shape of edge-on disk galaxies - III. Modelling the HI observations: results
• On the 3 dimensional structure of edge-on disk galaxies
• Numerical Modelling of the Vertical Structure and Dark Halo Parameters in Disc Galaxies
• The dark matter halo shape of edge-on disk galaxies - IV. UGC 7321
• The dark matter halo shape of edge-on disk galaxies - I. HI observations
• Linking star formation thresholds and truncations in the thin and thick disks of the low-mass galaxy UGC 7321
• Edge-on Low-surface-brightness Galaxy Candidates Detected from SDSS Images Using YOLO
• Patterns in the Outer Parts of Galactic Disks
• Stellar tidal streams around nearby spiral galaxies with deep imaging from amateur telescopes
• HI 21 cm observation and mass models of the extremely thin galaxy FGC 1440
• Hidden Figures in the Sky: Evolution of low-surface brightness galaxies from a hydro-dynamical perspective