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Rotational Velocities of Very Low Mass Binaries

Konopacky, Q. M. and Ghez, A. M. and Macintosh, B. A. and White, R. J. and Barman, T. S. and Rice, E. L. and Hallinan, G. (2011) Rotational Velocities of Very Low Mass Binaries. In: The 16th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun. Astronomical Society of the Pacific Conference Series. No.448. San Francisco, CA , Astronomical Society of the Pacific, pp. 147-154. ISBN 978-1-58381-776-6.

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We present rotational velocities for individual components of eleven very low mass (VLM) binaries with spectral types between M7.5 and L4. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the Keck II laser guide star adaptive optics (LGS AO) system. The binaries were targeted as part of a dynamical mass program, and their orbital inclinations are used to translate vsini into a rotational velocity for each component. We find that the observed sources tend to be rapid rotators (vsini > 10 km s^(-1)), consistent with previous measurements for ultracool objects. Five systems have component vsini's that are statistically different, with three binaries having velocity differences greater than 25 km s^(-1). To bring these discrepant rotational velocities into agreement would require their rotational axes to be inclined between 10 to 40° with respect to each other, and that at least one component has a significant inclination with respect to the orbital plane. Alternatively, each component could be rotating at a different rate, even though they have similar spectral types. Both differing rotational velocities and inclinations have interesting implications for binary star formation. Two of the binaries with large differences in rotational velocity are also known radio sources, LP 349-25AB and 2MASS 0746+20AB. LP 349-25B is rotating at ∼95 km s^(-1), within a factor of ∼3 of the break up speed, and is one of the most rapidly rotating VLM objects known.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Konopacky, Q. M.0000-0002-9936-6285
Ghez, A. M.0000-0003-3230-5055
Macintosh, B. A.0000-0003-1212-7538
Barman, T. S.0000-0002-7129-3002
Rice, E. L.0000-0002-3252-5886
Hallinan, G.0000-0002-7083-4049
Additional Information:© 2011 Astronomical Society of the Pacific. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC52- 07NA27344. This work is support by NASA Origins Grant NNX1 OAH39G. The W.M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck foundation.
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC52-07NA27344
W. M. Keck FoundationUNSPECIFIED
Series Name:Astronomical Society of the Pacific Conference Series
Issue or Number:448
Record Number:CaltechAUTHORS:20140204-135110759
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43653
Deposited By: Tony Diaz
Deposited On:25 Feb 2014 00:03
Last Modified:14 Oct 2019 22:00

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