A Method for Selecting M dwarfs with an Increased Likelihood of Unresolved
Ultra-cool Companionship
Neil Cook
University of Hertfordshire
Locating ultra-cool companions to M dwarfs is important for constraining
low-mass formation models, the measurement of sub-stellar dynamical masses
and radii, and for testing ultra-cool evolutionary models. We present an
optimised method for identifying M dwarfs which may have unresolved
ultra-cool companions. We construct a catalogue of 440,694 M dwarf
candidates, from WISE, 2MASS and SDSS, based on optical and near-infrared
colours and reduced proper motion. With strict reddening, photometric and
quality constraints we isolate a sub-sample of 36,898 M dwarfs and search
for possible mid-infrared M dwarf + ultra-cool dwarf candidates by
comparing M dwarfs which have similar optical/near-infrared colours (chosen
for their sensitivity to effective temperature and metallicity). We present
1,082 M dwarf + ultra-cool dwarf candidates for follow-up. Using simulated
ultra-cool dwarf companions to M dwarfs, we estimate that the occurrence of
unresolved ultra-cool companions amongst our M dwarf + ultra-cool dwarf
candidates should be at least four times the average for our full M dwarf
catalogue. We discuss possible contamination and bias and predict yields of
candidates based on our simulations.
Date: | Thursday, 17 December 2015 |
Time: | 11:30 |
Where: | Université de Montréal |
| Pavillon Roger-Gaudry, local D-460 |
Contact: | Julie Hlavacek-Larrondo |
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