H. R. Jacobson, E. D. Friel, L. Jílková, L. Magrini, A. Bragaglia, A. Vallenari, M. Tosi, S. Randich, P. Donati, T. Cantat-Gaudin, R. Sordo, R. Smiljanic, J. Overbeek, G. Carraro, G. Tautvai¨ienė, I. San Roman, S. Villanova, D. Geisler, C. Muñoz, F. Jiménez-Esteban, B. Tang, G. Gilmore, E. J. Alfaro, T. Bensby, E. Flaccomio, S. Koposov, A. J. Korn, E. Pancino, A. Recio-Blanco, A. Casey, M. T. Costado, E. Franciosini, U. Heiter, V. Hill, A. Hourihane, C. Lardo, P. de Laverny, J. Lewis, L. Monaco, L. Morbidelli, G. G. Sacco, S. G. Sousa, C. Worley, S. Zaggia
Abstract
Context. The nature of the metallicity gradient inside the solar circle (RGC < 8 kpc) is poorly understood, but studies of Cepheids and a small sample of open clusters suggest that it steepens in the inner disk.
Aims: We investigate the metallicity gradient of the inner disk using a sample of inner disk open clusters that is three times larger than has previously been studied in the literature to better characterize the gradient in this part of the disk.
Methods: We used the Gaia-ESO Survey (GES) [Fe/H] values and stellar parameters for stars in 12 open clusters in the inner disk from GES-UVES data. Cluster mean [Fe/H] values were determined based on a membership analysis for each cluster. Where necessary, distances and ages to clusters were determined via comparison to theoretical isochrones.
Results: The GES open clusters exhibit a radial metallicity gradient of -0.10 ± 0.02 dex kpc-1, consistent with the gradient measured by other literature studies of field red giant stars and open clusters in the range RGC ~ 6-12 kpc. We also measure a trend of increasing [Fe/H] with increasing cluster age, as has also been found in the literature.
Conclusions: We find no evidence for a steepening of the inner disk metallicity gradient inside the solar circle as earlier studies indicated. The age-metallicity relation shown by the clusters is consistent with that predicted by chemical evolution models that include the effects of radial migration, but a more detailed comparison between cluster observations and models would be premature.
Keywords
Galaxy: formation, Galaxy: disk, Galaxy: abundances, stars: abundances
Notes Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A37
Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002 and 193.B-0936. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council.
Astronomy & Astrophysics
Volume 591, Article Number A37, Number of pages 8
2016 July
