MAD about the Large Magellanic Cloud: preparing for the era of Extremely Large Telescopes

Abstract

We present J, H, Ks photometry from the the Multi conjugate Adaptive optics Demonstrator (MAD), a visitor instrument at the VLT, of a resolved stellar population in a small crowded field in the bar of the Large Magellanic Cloud near the globular cluster NGC 1928. In a total exposure time of 6, 36 and 20 minutes, magnitude limits were achieved of J \sim 20.5 mag, H \sim 21 mag, and Ks \sim20.5 mag respectively, with S/N> 10. This does not reach the level of the oldest Main Sequence Turnoffs, however the resulting Colour-Magnitude Diagrams are the deepest and most accurate obtained so far in the infrared for the LMC bar. We combined our photometry with deep optical photometry from the Hubble Space Telescope/Advanced Camera for Surveys, which is a good match in spatial resolution. The comparison between synthetic and observed CMDs shows that the stellar population of the field we observed is consistent with the star formation history expected for the LMC bar, and that all combinations of IJHKs filters can, with some care, produce the same results. We used the Red Clump magnitude in Ks to confirm the LMC distance modulus as, μ0=18.50\pm0.06r \pm0.09s mag. We also addressed a number of technical aspects related to performing accurate photometry with adaptive optics images in crowded stellar fields, which has implications for how we should design and use the Extremely Large Telescopes of the future for studies of this kind.

11 pages, 14 figures, accepted on A&A

References in corpus (6)

• Evidence for an Overluminosity of the Variable Star RR Lyr, and a Revised Distance to the LMC
• MCAO near-IR photometry of the Globular Cluster NGC 6388: MAD observations in crowded fields
• Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys - II. The unique LMC cluster ESO 121-SC03
• An E-ELT Case Study: Colour-Magnitude Diagrams of an Old Galaxy in the Virgo Cluster
• Resolving Stellar Populations outside the Local Group: MAD observations of UKS2323-326
• Multi-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR1415

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• The absolute age of the globular cluster M15 using near-infrared adaptive optics images from PISCES/LBT
• Towards Precision Photometry with Extremely Large Telescopes: the Double Subgiant Branch of NGC 1851
• Ultra Long Period Cepheids: a primary standard candle out to the Hubble flow
• Kinematic Structure of the Large Magellanic Cloud Globular Cluster System from Gaia eDR3 and Hubble Space Telescope Proper Motions
• Studying the metallicity gradient in Virgo Ellipticals with E-ELT photometry of resolved stars
• Optimal stellar photometry for multi-conjugate adaptive optics systems using science-based metrics
• Stellar photometry with Multi Conjugate Adaptive Optics
• On the use of asymmetric PSF on NIR images of crowded stellar fields
• Exploration about the origin of galactic and extragalactic star clusters through simulated H-R diagrams