Physical properties of circumnuclear ionising clusters. III. Kinematics of gas and stars in NGC 7742

Abstract

In this third paper of a series, we study the kinematics of the ionised gas and stars, calculating the dynamical masses of the circumnuclear star-forming regions in the ring of of the face-on spiral NGC 7742. We have used high spectral resolution data from the MEGARA instrument attached to the Gran Telescopio Canarias (GTC) to measure the kinematical components of the nebular emission lines of selected HII regions and the stellar velocity dispersions from the CaT absorption lines that allow the derivation of the associated cluster virialized masses. The emission line profiles show two different kinematical components: a narrow one with velocity dispersion $\sim$ 10 km/s and a broad one with velocity dispersion similar to those found for the stellar absorption lines. The derived star cluster dynamical masses range from 2.5 $\times$ 10${}^6$ to 10.0 $\times$ 10${}^7$ M${}_{\odot }$. The comparison of gas and stellar velocity dispersions suggests a scenario where the clusters have formed simultaneously in a first star formation episode with a fraction of the stellar evolution feedback remaining trapped in the cluster, subject to the same gravitational potential as the cluster stars. Between 0.15 and 7.07 % of the total dynamical mass of the cluster would have cooled down and formed a new, younger, population of stars, responsible for the ionisation of the gas currently observed.

14 pages, 14 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (13)

• A SINFONI view of Galaxy Centers: Morphology and Kinematics of five Nuclear Star Formation Rings
• A Connection between Star Formation in Nuclear Rings and their Host Galaxies
• The metal abundance of circumnuclear star forming regions in early type spirals. Spectrophotometric observations
• Star formation and stellar populations across nuclear rings in galaxies
• HST/STIS spectroscopy of the environment in the starburst core of M82
• Gemini GMOS/IFU spectroscopy of NGC 1569 - II: Mapping the roots of the galactic outflow
• Kinematics of gas and stars in the circumnuclear starforming ring of NGC 3351
• X-ray Properties of NGC 253's Starburst-Driven Outflow
• The Morpho-Kinematic Architecture of Super Star Clusters in the Center of NGC253
• The resolved chemical composition of the starburst dwarf galaxy CGCG007-025: Direct method versus photoionization model fitting
• MEGARA-GTC Stellar Spectral Library (I)
• Physical properties of circumnuclear ionising clusters. I. NGC 7742
• Physical properties of circumnuclear ionising clusters. II. NGC 7469