SpeX Spectroscopy of Unresolved Very Low-Mass Binaries. I. Identification of Seventeen Candidate Binaries Straddling the L Dwarf/T Dwarf Transition

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Burgasser, Adam J. ; Cruz, Kelle L. ; Cushing, Michael C. ; Gelino, Christopher R. ; Looper, Dagny L. ; Faherty, Jacqueline K. ; Kirkpatrick, J. Davy ; Reid, I. Neill (2009)
  • Publisher: American Astronomical Society
  • Related identifiers: doi: 10.1088/0004-637X/710/2/1142
  • Subject: Astrophysics - Solar and Stellar Astrophysics
    arxiv: Astrophysics::Galaxy Astrophysics | Astrophysics::Cosmology and Extragalactic Astrophysics | Astrophysics::Earth and Planetary Astrophysics | Astrophysics::Solar and Stellar Astrophysics

We report the identification of 17 candidate brown dwarf binaries whose components straddle the L dwarf/T dwarf transition. These sources were culled from a large near-infrared spectral sample of L and T dwarfs observed with the Infrared Telescope Facility SpeX spectrograph. Candidates were selected on the basis of spectral ratios which segregate known (resolved) L dwarf/T dwarf pairs from presumably single sources. Composite templates, constructed by combining 13581 pairs of absolute flux-calibrated spectra, are shown to provide statistically superior fits to the spectra of our seventeen candidates as compared to single templates. Ten of these candidates appear to have secondary components that are significantly brighter than their primaries over the 1.0-1.3 micron band, indicative of rapid condensate depletion at the L dwarf/T dwarf transition. Our results support prior indications of enhanced multiplicity amongst early-type T dwarfs; 53+/-7% of the T0-T4 dwarfs in our spectral sample are found to be either resolved or unresolved (candidate) pairs, although this is consistent with an intrinsic (volume complete) brown dwarf binary fraction of only 15%. If verified, this sample of spectral binaries more than doubles the number of known L dwarf/T dwarf transition pairs, enabling a broader exploration of this poorly-understood phase of brown dwarf atmospheric evolution.
  • References (10)

    Ackerman, A. S., & Marley, M. S. 2001, ApJ, 556, 872 Burgasser, A. J., McElwain, M. W., & Kirkpatrick, J. D. 2003d, AJ, 126, 2487 Burgasser, A. J., McElwain, M. W., Kirkpatrick, J. D., Cruz, K. L., Tinney, C. G., & Reid, I. N. 2004, AJ, 127, 2856

    Burgasser, A. J., Reid, I. N., Leggett, S. K., Kirkpatrick, J. D., Liebert, J., & Burrows, A. 2005b, ApJ, 634, L177

    Burgasser, A. J., Reid, I. N., Siegler, N., Close, L., Allen, P., Lowrance, P., & Gizis, J. 2007b, Protostars and Planets V, 427

    Burgasser, A. J., et al. 1999, ApJ, 522, L65 Dupuy, T. J., Liu, M. C., & Ireland, M. J. 2009, ApJ, 692, 729 Duquennoy, A., & Mayor, M. 1991, A&A, 248, 485 Ellis, S. C., Tinney, C. G., Burgasser, A. J., Kirkpatrick, J. D., & McElwain, M. W. 2005, AJ, 130, 2347

    Epchtein, N., et al. 1997, The Messenger, 87, 27 Faherty, J. K., Burgasser, A. J., Cruz, K. L., Shara, M. M., Walter, F. M., & Gelino, C. R. 2009, AJ, 137, 1

    Kirkpatrick, J. D., Reid, I. N., Liebert, J., Gizis, J. E., Burgasser, A. J., Monet, D. G., Dahn, C. C., Nelson, B., & Williams, R. J. 2000, AJ, 120, 447

    Kirkpatrick, J. D., et al. 1999, ApJ, 519, 802 Martin, E. L., Brandner, W., & Basri, G. 1999, Science, 283, 1718 McCaughrean, M. J., Close, L. M., Scholz, R.-D., Lenzen, R., Biller, B., Brandner, W., Hartung, M., & Lodieu, N. 2004, A&A, 413, 1029

    McElwain, M. W., & Burgasser, A. J. 2006, AJ, 132, 2074 McLean, I. S., McGovern, M. R., Burgasser, A. J., Kirkpatrick, J. D., Prato, L., & Kim, S. S. 2003, ApJ, 596, 561

    Simons, D. A., & Tokunaga, A. 2002, PASP, 114, 169 Skrutskie, M. F., et al. 2006, AJ, 131, 1163 Stassun, K. G., Mathieu, R. D., & Valenti, J. A. 2006, Nature, 440, 311 Stephens, D. C., et al. 2009, ApJ, 702, 154 Strauss, M. A., et al. 1999, ApJ, 522, L61 Stumpf, M. B., Brandner, W., Henning, T., Bouy, H., Koehler, R., Hormuth, F., Joergens, V., & Kasper, M. 2008, ArXiv e-prints

    Testi, L., et al. 2001, ApJ, 552, L147 Tinney, C. G., Burgasser, A. J., & Kirkpatrick, J. D. 2003, AJ, 126, 975 Tinney, C. G., Burgasser, A. J., Kirkpatrick, J. D., & McElwain, M. W. 2005, AJ, 130, 2326 Tokunaga, A. T., Simons, D. A., & Vacca, W. D. 2002, PASP, 114, 180

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