Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published 2011 | Published
Book Section - Chapter Open

Rotational Velocities of Very Low Mass Binaries


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.

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.

Attached Files

Published - Konopacky_2011p147.pdf


Files (143.9 kB)
Name Size Download all
143.9 kB Preview Download

Additional details

August 19, 2023
January 13, 2024