PI Total time #CoIs, team Fernando Comerón 2n (ELT 42m) Not many people Low-mass brown dwarf formation in the Magellanic Clouds: A population long gone into obscurity in our neighbourhood The Magellanic Clouds are the only nearby place where low- metallicity, very low-mass brown dwarfs are accessible to observation. And the ELT will be the only telescope reaching the depth and resolution needed to reveal them.

Scientific rationale Our Galaxy may have produced huge numbers of low metallicity, very low mass (a few M Jup ) brown dwarfs in its infancy –but they have faded beyond detection long since then: 10 M Jup at 5 Gyr  M K = 30.5, H-K=-7.2 However, we can watch them forming now in the LMC and SMC –if they form at all! At K=28, M lim = 6 M Jup (1 Myr); 15 M Jup (10 Myr); reachable in 2h at S/N>5 with a 42m ELT (similar times and limits for J, H). A low-mass star forming cloud is only ~2’’across at the LMC distance  LTAO can yield nearly diffraction- limited image cores of the whole cluster, reach very deep, and overcome confusion.

Immediate objectives -Observe low-mass SFR in the LMC and SMC. -Identify the lowest-mass objects from their position in color-color-magnitude diagrams. -Spectroscopy of the brightest candidates is possible -Compare mass functions to galactic, solar metallicity counterparts (we will know much more about those thanks to VISTA) -Extrapolate numbers over the history of the Milky Way: how abundant are old, low-metallicity low-mass brown dwarfs? -What if none is found? Is there a minimum mass threshold that depends on metallicity?

RunTargetR.A.Dec.ToTMagNotes ALMC5.4h-69˚5h<29S/N > 3 BSMC0.8h-72˚5h<29S/N > 3 ELT Justification: milliarcsecond-level resolution is needed down to K ~ 28. Legacy Value: Complete stellar and substellar IMFs in a low metallicity environment will be obtained. Data Reduction: Not particularly challenging from this point of view –crowded field photometry? RunMPModeAOT.FOVPixel Notes A-ImagingLTAO1n2’’10JHKZ = 0.3 B-ImagingLTAO1n2’’10JHKZ = 0.1