NOAO >   Observing Info >   Approved Programs >   2009A-0178

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Proposal Information for 2009A-0178


PI: Sergio Dieterich, Georgia State University, dieterich@chara.gsu.edu
Address: Department of Physics and Astronomy, Atlanta, GA, 30302, USA

CoI: Todd Henry, Gerogia State University
CoI: David Golimowski, Space Telescope Science Institute

Title: GJ 433: Resolving a Suspected Binary Near the Stellar/Substellar Boundary

Abstract: We propose to obtain high resolution images of the suspected very low mass binary GJ 433 AB using NIRI+ALTAIR on Gemini North. The duplicity of GJ 433 was first indicated by a perturbation in Hipparcos data, and later by speckle observations (Bernstein, 1997). Our own HST/NICMOS observations revealed the companion but the 75 mas pixels do not allow us to measure an accurate separation or position angle. The combination of Hipparcos astrometry, the single IR speckle measurement, and tentative NICMOS photometry indicate that the B component has a mass very near the hydrogen burning mass limit, between 0.122 and 0.088 solar masses. Although much work has been done in the field of brown dwarfs during the past decade, the fundamental question of where the exact boundary between stellar and substellar object lies is still largely not addressed due to the lack of reliable observational tests that discriminate between the most massive brown dwarfs and the least massive stars. Characterizing objects near this boundary is a fundamental aspect of the PI's doctoral thesis. Here we propose to observe GJ 433 twice to obtain J, H, and K photometry and begin mapping the orbit, which has a period of about 1.5 years from the Hipparcos data, to provide a crucial point in the Mass-Luminosity Relation near the end of the stellar main sequence.


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