Search for Slow Bars in Two Barred Galaxies with Nuclear Structures: NGC 6951 and NGC 7716

TL;DR

This study examines two barred galaxies with nuclear structures to determine if they host slow bars, revealing that slow bars are often associated with nuclear features and galaxy interactions, which influence bar evolution.

Contribution

It provides the first detailed analysis of slow bars in galaxies with nuclear structures using spectroscopic and imaging data, highlighting the role of interactions in bar dynamics.

Findings

NGC 6951 hosts a slow, long, and strong bar.

Nuclear disks and rings are present in both galaxies.

Weak primary bars may be linked to nuclear structures and interactions.

Abstract

We investigate two barred galaxies with nuclear structures, NGC 6951 and NGC 7716, to examine whether they host slow bars. Using Gemini/GMOS long-slit spectroscopy, we calculate the bar pattern speed with the Tremaine-Weinberg method and detect kinematically decoupled nuclear disks in both galaxies. We also measure the bar length and strength using Pan-STARRs images and identify a nuclear ring in NGC 6951 and a nuclear bar in NGC 7716 from HST/PC images. Our results indicate that NGC 6951 hosts a slow, long, and strong bar, which likely evolved through interactions with the dark matter halo and contributed to the formation of both the nuclear disk and ring. We also find hints of a rapidly rotating oval structure within the primary bar, although it is not clearly seen in the imaging data. In contrast, the primary bar in NGC 7716 is too weak to be classified as a barred galaxy, while its nuclear disk and nuclear bar are unusually large, possibly due to tidal interactions or the weakness of the primary bar. These findings suggest that slow bars may be more observed in galaxies with nuclear structures and highlight the often underappreciated role of galaxy interactions in bar evolution.