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Physical Properties of Young Brown Dwarfs and Very Low Mass Stars Inferred from High-resolution Model Spectra

Rice, Emily L. and Barman, T. and McLean, Ian S. and Prato, L. and Kirkpatrick, J. Davy (2010) Physical Properties of Young Brown Dwarfs and Very Low Mass Stars Inferred from High-resolution Model Spectra. Astrophysical Journal Supplement Series, 186 (1). pp. 63-84. ISSN 0067-0049.

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By comparing near-infrared spectra with atmospheric models, we infer the effective temperature, surface gravity, projected rotational velocity, and radial velocity for 21 very low mass stars and brown dwarfs. The unique sample consists of two sequences in spectral type from M6-M9, one of 5-10 Myr objects and one of >1 Gyr field objects. A third sequence is comprised of only ~M6 objects with ages ranging from <1 Myr to >1 Gyr. Spectra were obtained in the J band at medium (R ~ 2000) and high (R ~ 20,000) resolutions with NIRSPEC on the Keck II telescope. Synthetic spectra were generated from atmospheric structures calculated with the PHOENIX model atmosphere code. Using multi-dimensional least-squares fitting and Monte Carlo routines we determine the best-fit model parameters for each observed spectrum and note which spectral regions provide consistent results. We identify successes in the reproduction of observed features by atmospheric models, including pressure-broadened K I lines, and investigate deficiencies in the models, particularly missing FeH opacity, that will need to be addressed in order to extend our analysis to cooler objects. The precision that can be obtained for each parameter using medium- and high-resolution near-infrared spectra is estimated and the implications for future studies of very low mass stars and brown dwarfs are discussed.

Item Type:Article
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URLURL TypeDescription
Rice, Emily L.0000-0002-3252-5886
Barman, T.0000-0002-7129-3002
Kirkpatrick, J. Davy0000-0003-4269-260X
Additional Information:© 2010 American Astronomical Society. Print publication: Issue 1 (2010 January); received 2009 March 25; accepted for publication 2009 November 20; published 2009 December 17. The authors thank the staff of the Keck Observatory for their outstanding support, including Joel Aycock, Randy Campbell, Al Conrad, Grant Hill, Jim Lyke, Steven Magee, Julie Renaud- Kim, Barbara Schaefer, Chuck Sorenson, Terry Stickel, and Cynthia Wilburn. Observing assistance from Antonia Hubbard, Quinn M. Konopacky, Gregory Mace, and Erin C. Smith and data reduction by Chalence Safranek-Schrader was greatly appreciated. E.L.R. acknowledges the hospitality of the research and administrative staff at Lowell Observatory. T.B. acknowledges the NASA Origins of Solar System program and the Mount Cuba Astronomical Fund for their generous support. I.S.M. acknowledges the staff of the UCLA Infrared Laboratory and colleagues James Graham (UCB), James Larkin (UCLA), and Eric Becklin (UCLA) for their support throughout the development of the NIRSPEC instrument. This paper benefited greatly from the detailed and thoughtful comments of the anonymous referee. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This publication makes use of data from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center, funded by the National Aeronautics and Space Administration and the National Science Foundation. This research has benefited from the M, L, and T dwarf compendium housed at and maintained by ChrisGelino, Davy Kirkpatrick, and Adam Burgasser. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France and NASA’s Astrophysics Data System. Finally, the authors wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Facilities: Keck:II (NIRSPEC)
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Mt. Cuba Astronomical FoundationUNSPECIFIED
Subject Keywords:infrared: stars; open clusters and associations: individual (Upper Scorpius, TW Hydrae Association); stars: atmospheres; stars: low-mass, brown dwarfs; techniques: spectroscopic
Issue or Number:1
Record Number:CaltechAUTHORS:20100120-105300878
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Official Citation:Physical Properties of Young Brown Dwarfs and Very Low Mass Stars Inferred from High-resolution Model Spectra Emily L. Rice, T. Barman, Ian S. Mclean, L. Prato, and J. Davy Kirkpatrick 2010 ApJS 186 63-84 doi: 10.1088/0067-0049/186/1/63
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17237
Deposited By: Jason Perez
Deposited On:25 Jan 2010 19:14
Last Modified:19 May 2020 22:34

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