Census of HII regions in NGC 6754 derived with MUSE: Constraints on the metal mixing scale

TL;DR

This study uses high-resolution MUSE integral field spectroscopy to catalog nearly 400 HII regions in NGC 6754, deriving metallicity gradients and mixing scales to understand metal distribution mechanisms in galaxy disks.

Contribution

It provides one of the largest spectroscopic catalogs of HII regions in a single galaxy and constrains metal mixing scales and azimuthal abundance variations.

Findings

Negative radial abundance gradient consistent with disk galaxy trends.

Estimated metal mixing scale-length of approximately 0.4 effective radii.

Evidence of azimuthal oxygen abundance variations linked to radial migration.

Abstract

We present a study of the HII regions in the galaxy NGC 6754 from a two pointing mosaic comprising 197,637 individual spectra, using Integral Field Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science Verification program. The data cover the entire galaxy out to ~2 effective radii (re ), sampling its morphological structures with unprecedented spatial resolution for a wide-field IFU. A complete census of the H ii regions limited by the atmospheric seeing conditions was derived, comprising 396 individual ionized sources. This is one of the largest and most complete catalogue of H ii regions with spectroscopic information in a single galaxy. We use this catalogue to derive the radial abundance gradient in this SBb galaxy, finding a negative gradient with a slope consistent with the characteristic value for disk galaxies recently reported. The large number of H ii regions allow us to estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong constraints on the proposed mechanisms for metal mixing in disk galaxies, like radial movements associated with bars and spiral arms, when comparing with simulations. We found evidence for an azimuthal variation of the oxygen abundance, that may be related with the radial migration. These results illustrate the unique capabilities of MUSE for the study of the enrichment mechanisms in Local Universe galaxies.