SCYON Abstract

Received on October 12 2004

NGC 6404 and NGC 6503: two intermediate-age open clusters located toward the Galactic center direction

AuthorsGiovanni Carraro (1,2), Rene Mendez (1), Edgardo Costa (1)
Affiliation1 Universidad de Chile
2 Yale University
Accepted byMonthly Notices of the Royal Astronomical Society


We report on VI CCD photometry of two fields centered in the region of the open clusters NGC 6404 and NGC 6583 down to V=22.0. These clusters have never been studied insofar, and we provide for the first time estimates of their fundamental parameters, namely, radial extent, age, distance and reddening. We find that NGC~6404 radius is 2.0 arcmin, as previously proposed, while NGC 6583 radius is 1.0 arcmin, significantly lower than previous estimates.

Both clusters turn out to be of intermediate age (0.5-1.0 Gyr old), and located inside the solar ring, at a Galactocentric distance of about 6.5 kpc. These results make these objects very interesting targets for spectroscopic follow-up to measure their metallicity. In fact they might allow us to enlarge by more than 1 kpc the baseline of the radial abundance gradient in the Galactic disk toward the Galactic Center direction. This baseline is currently rather narrow especially for clusters of this age.