NOAO >   Observing Info >   Approved Programs >   2011A-0285

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Proposal Information for 2011A-0285


PI: Ray Jayawardhana, University of Toronto, rayjay@astro.utoronto.ca
Address: Department of Astronomy, 50 St. George Street, Toronto, ON M5S 3H8, Canada

CoI: Markus Janson, University of Toronto
CoI: Mariangela Bonavita, Univ. of Toronto
CoI: David Lafreniere, University of Montreal
CoI: John Gizis, University of Delaware
CoI: Kristen Menou, Columbia University

Title: Supermassive Planets or Ultralight Brown Dwarfs? A New Population of Wide Substellar Companions

Abstract: Numerous radial velocity and direct imaging studies have noted a deficit of brown dwarf companions to (solar-type) stars at a range of orbital separations. Yet, recent higher-contrast observations have revealed a number of substellar companions in orbits as wide as 300-900 AU, including some with masses near and below 15Mjup. These exciting discoveries hint at a population of substellar companions, with mass ratios as low as 0.01, particularly around >1 Msun stars. These objects may represent the bottom end of the stellar companion mass function or the top end of the planet population, though both scenarios pose challenges to conventional formation models. Here we propose to determine the frequency and characteristics of ultra-low-mass companions to stars of solar mass and above, by targeting a sample of 141 members of the nearby ( 118-145 pc), young ( 5-13 Myr) Sco-Cen association, with GeminiSouth/NICI. These stars have never been observed with AO before, and are prime targets for future GPI and JWST campaigns. The multiplicity information that an AO survey like this provides is a vital target selection criterion for such surveys.


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NOAO >   Observing Info >   Approved Programs >   2011A-0285

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