MUSE observations of the counter-rotating nuclear ring in NGC 7742

Abstract

We present results from MUSE observations of the nearly face-on disk galaxy NGC 7742. This galaxy hosts a spectacular nuclear ring of enhanced star formation, which is unusual in that it is hosted by a non-barred galaxy, and also because this star formation is most likely fuelled by externally accreted gas that counter-rotates with respect to its main stellar body. We use the MUSE data to derive the star-formation history (SFH) and accurately measure the stellar and ionized-gas kinematics of NGC7742 in its nuclear, bulge, ring, and disk regions. We map the previously known gas counter-rotation well outside the ring region and deduce the presence of a slightly warped inner disk, which is inclined ~6 degrees compared to the outer disk. The gas-disk inclination is well constrained from the kinematics; the derived inclination 13.7 $\pm$ 0.4 degrees agrees well with that derived from photometry and from what one expects using the inverse Tully-Fisher relation. We find a prolonged SFH in the ring with stellar populations as old as 2-3 Gyr and an indication that the star formation triggered by the minor merger event was delayed in the disk compared to the ring. There are two separate stellar components: an old population that counter-rotates with the gas, and a young one, concentrated to the ring, that co-rotates with the gas. We recover the kinematics of the old stars from a two-component fit, and show that combining the old and young stellar populations results in the erroneous average velocity of nearly zero found from a one-component fit. The superior spatial resolution and large field of view of MUSE allow us to establish the kinematics and SFH of the nuclear ring in NGC 7742. We show further evidence that this ring has its origin in a minor merger event, possibly 2-3 Gyr ago.

arXiv comment9 pages, 10 figures, accepted for publication in A&A

References in corpus (28)

• The Host Galaxies of AGN
• Parametric Recovery of Line-of-Sight Velocity Distributions from Absorption-Line Spectra of Galaxies via Penalized Likelihood
• Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
• Adaptive spatial binning of integral-field spectroscopic data using Voronoi tessellations
• The SAURON project - V. Integral-field emission-line kinematics of 48 elliptical and lenticular galaxies
• An updated MILES stellar library and stellar population models
• Automated data reduction workflows for astronomy
• The SAURON project. II. Sample and early results
• The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies
• The Ursa Major Cluster of Galaxies. V ; HI Rotation Curve Shapes and the Tully-Fisher Relations
• Central Rotation Curves of Spiral Galaxies
• The SAURON project - VII. Integral-field absorption and emission-line kinematics of 24 spiral galaxy bulges
• The Central Region in M100: Observations and Modeling
• AINUR: Atlas of Images of NUclear Rings
• Unequal-mass galaxy mergers and the creation of cluster S0 galaxies
• The DiskMass Survey. VI. Gas and stellar kinematics in spiral galaxies from PPak integral-field spectroscopy
• Structure and star formation in disk galaxies III. Nuclear and circumnuclear H alpha emission
• Ionized gas and stellar kinematics of seventeen nearby spiral galaxies
• The Star Formation History and Evolution of the Circumnuclear Region of M100
• Dating the formation of the counter-rotating stellar disc in the spiral galaxy NGC 5719 by disentangling its stellar populations
• Star formation and stellar populations across nuclear rings in galaxies
• The nuclear ring in the unbarred galaxy NGC 278: result of a minor merger?
• The SAMI Pilot Survey: Stellar Kinematics of Galaxies in Abell 85, 168 and 2399
• Nature of nuclear rings in unbarred galaxies: NGC 7742 and NGC 7217
• Minor Merger Origin for the Circumnuclear Starburst in NGC 7742
• The Formation of S0 Galaxies with Counter-Rotating Neutral and Molecular Hydrogen
• Probing Circumnuclear Environments with the HCN(J = 3-2) and HCO+(J = 3-2) lines: Case of NGC 1097
• Kinematic and stellar population properties of the counter-rotating components in the S0 galaxy NGC 1366

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