Multi-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR1415

TL;DR

This study uses advanced adaptive optics imaging to analyze a distant, old open cluster in the Milky Way, providing detailed properties such as distance, age, metallicity, and mass function.

Contribution

First application of MAD adaptive optics to characterize a distant old open cluster, achieving high-resolution imaging and detailed astrophysical parameters.

Findings

Distance of ~8.6 kpc determined

Age estimated at ~2.5 Gyr

Mass function indicates a relatively massive cluster

Abstract

We employ the recently installed near infrared Multi-Conjugate Adaptive optics demonstrator (MAD) to determine basic properties of a newly identified, old and distant, Galactic open cluster (FSR1415). 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% 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 allow us to reconstruct (completeness-corrected) mass functions indicating a relatively massive cluster, with a flat core MF. The VLT/MAD capabilities will therefore provide fundamental data in identifying/analyzing other faint and distant open clusters in the Galaxy III and IV quadrants.