A benchmark for multiconjugated adaptive optics: VLT–MAD observations of the young massive cluster Trumpler 14

The Multi-conjugate Adaptive optics Demonstrator (MAD) is the first multiconjugated adaptive optics system at the Very Large Telescope (VLT). We present H and KS observations of the young massive cluster Trumpler 14 revealing the power of MCAO systems by providing a homogeneous Strehl ratio over a large field of view. Mean Strehl ratios of 6.0 and 5.9 per cent with maximum Strehl ratios of 9.8 and 12.6 per cent in H and KS, respectively, show significant improvement of the spatial point spread function (PSF) stability compared to single-conjugated adaptive optics systems. Photometry of our observations cover a dynamic range of ∼10 mag including 2–3 times greater number of sources than comparable seeing-limited observations. The colour–magnitude diagram reveals that the massive cluster originated in a recent starburst-like event 1 ± 0.5 Myr ago. We tentatively detect hints for an older population of 3 Myr suggesting that low intensity star formation might have been going on in the Hii region for a few Myr. We derive the luminosity function and mass function between 0.1 and 3.2 M⊙ and identify a change in the power-law slope of the mass function at mc∼ 0.53+0.12− 0.10 M⊙. The MF appears shallow with power-law slopes of Γ1=−0.50 ± 0.11 above mc and Γ2= 0.63 ± 0.32 below mc.