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

© ESO 2014. SFS thanks the director of CEFCA, M. Moles, for his sincere support. We thank the referee for his/her comments that have improved this manuscript. Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 60.A-9329. Support for L.G. and H.K. is provided by the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC12009, awarded to The Millennium Institute of Astrophysics, MAS. L.G. and H.K. acknowledge support by CONICYT through FONDECYT grants 3140566 and 3140563, respectively. S.F.S. acknowledges the Mexican National Council for Science and Technology (CONACYT) for financial support under the program Proyectos de Ciencia Básica. E.P. acknowledges funding from the Spanish MINECO grant AYA2010-15081. RA Marino was also funded by the Spanish programme of International Campus of Excellence Moncloa (CEI).
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 spectroscopy recently acquired with the MUSE instrument during its Science Verification program. The data cover the entire galaxy out to similar to 2 effective radii (r(e)), sampling its morphological structures with unprecedented spatial resolution for a wide-field Integral Field Unit. A complete census of the HII regions limited by the atmospheric seeing conditions was derived, comprising 396 individual ionized sources. This is one of the largest and most complete catalogues of HII 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 HII regions allows us to estimate the typical mixing scale length (r(mix) similar to 0.4 r(e)), which sets strong constraints on the proposed mechanisms for metal mixing in disk galaxies, like radial movements associated with bars and spiral arms. We found evidence of an azimuthal variation in the oxygen abundance that may be connected with the radial migration. These results illustrate the unique capabilities of MUSE for the study of the enrichment mechanisms in Local Universe galaxies.
Ministry of Economy, Development, and Tourism's Millennium Science Initiative
CONICYT through FONDECYT
Mexican National Council for Science and Technology (CONACYT)
Spanish MINECO
Spanish programme of International Campus of Excellence Moncloa (CEI)
ESO Telescopes at the Paranal Observatory
Depto. de Física de la Tierra y Astrofísica
Fac. de Ciencias Físicas
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