Journal Article

Multi-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR 1415

Y. Momany, S. Ortolani, C. Bonatto, E. Bica and B. Barbuy

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 391, issue 4, pages 1650-1658
Published in print December 2008 | ISSN: 0035-8711
Published online December 2008 | e-ISSN: 1365-2966 | DOI:

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We employ the recently installed near-infrared Multi-Conjugate Adaptive Optics demonstrator (MAD) to determine the basic properties of a newly identified, old and distant, Galactic open cluster (FSR 1415). The MAD facility remarkably approaches the diffraction limit, reaching a resolution of 0.07 arcsec (in K), that is also uniform in a field of ∼1.8 arcmin in diameter. The MAD facility provides photometry that is 50 per cent complete at K∼ 19. This corresponds to about 2.5 mag below the cluster main-sequence turn-off. This high-quality data set allows us to derive an accurate heliocentric distance of 8.6 kpc, a metallicity close to solar and an age of ∼2.5 Gyr. On the other hand, the deepness of the data allows us to reconstruct (completeness-corrected) mass functions (MFs) indicating a relatively massive cluster, with a flat core MF. The Very Large Telescope/MAD capabilities will therefore provide fundamental data for identifying/analysing other faint and distant open clusters in the Galaxy III and IV quadrants.

Keywords: instrumentation: adaptive optics; techniques: photometric; stars: Population II; open clusters and associations: individual: FSR 1415; infrared: stars

Journal Article.  5939 words.  Illustrated.

Subjects: Astronomy and Astrophysics