PI: Kevin Luhman, Pennsylvania State U., email@example.com
Address: 525 Davey Lab, University Park, PA, 16802 USA
CoI: Tara Esplin, U. of Arizona
Title: Toward a Complete Census of Brown Dwarfs in Upper Sco
Abstract: The shape of the substellar mass function and its minimum mass can provide fundamental tests of theories of star formation. The Upper Sco OB association contains the largest stellar population at ages of <10 Myr and distances of <150 pc (~2000 stars). As a result, it offers the best available statistical constraints on the IMF of brown dwarfs. The recent data releases from Gaia, Pan-STARRS1, and the VISTA Hemisphere Survey combined with previous data from 2MASS, UKIDSS and WISE have now made it possible to perform a thorough survey for brown dwarfs in Upper Sco down to 0.005-0.01 solar masses (5-10 Jupiter masses). We have used proper motions and color-magnitude diagrams measured with those databases to identify candidate brown dwarfs in Upper Sco. During Fast Turnaround programs at Gemini in 2017A, we obtained GNIRS spectra of an initial sample of 8 candidates to verify that they are young late-type objects, and hence members of the association. All of those candidates were confirmed as substellar members of Upper Sco, which demonstrates the validity of our selection criteria. We now propose GNIRS spectroscopy for our remaining 70 candidates at K>14 (<0.04 solar masses) to confirm their membership. When combined with spectroscopy on other telescopes that we are proposing for brighter candidates at higher masses, the proposed GNIRS observations will provide a census of substellar members of Upper Sco that has completeness/detection limits of ~0.01/0.005 solar masses. A majority of these targets are bright enough to be observed during poor conditions (IQ=85/CC=70).
Program Type: Standard/Galactic
Run 1 (2018A): GEM-NQ/GNIRS -- 42.4hrs band 2 (GN-2018A-Q-218 )
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360