NOAO >   Observing Info >   Approved Programs >   2010B-0467

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Proposal Information for 2010B-0467


PI: Sergio Dieterich, Georgia State University, dieterich@chara.gsu.edu
Address: Department of Physics and Astronomy, Atlanta, GA, 30303, USA

CoI: Todd Henry, Georgia State University

Title: Probing Stellar Physics at the Bottom of the Main Sequence: Calibrating the Effects of Youth, Gravity, and Metallicity on Luminosity

Abstract: We propose to use GMOS-S to obtain medium resolution (R 4500) optical red spectra of 27 field late M and early L dwarfs. All objects have either preliminary or final trigonometric parallaxes placing them within 25 pc of the Sun. The spectral region from 6500 A to 9000 A is rich with well known absorption features useful in measuring the relative effects of gravity, youth, and metallicity in these ultracool dwarfs. All targets are members of a larger sample of 116 objects around the stellar/substellar transition for which we are obtaining optical (VRI) photometry, trigonometric parallaxes, and refined spectral typing. By correlating the equivalent widths of gravity, youth, and metallicity indicators to an object's precise position in a parallax calibrated color-magnitude diagram, we will for the first time gain an empirical quantitative idea of how these parameters affect overall luminosity. Gravity and age effects play an important role in our understanding of the stellar/substellar transition, as objects in this spectral type range comprise a mixture of very low mass stars and high mass or young brown dwarfs. Characterizing the observational properties of this complex mix of objects is the key goal of the PI's doctoral dissertation.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2010B-0467

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