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Discovery of two young brown dwarfs in an eclipsing binary system

Nature volume 440, pages 311–314 (2006)Cite this article

Abstract

Brown dwarfs are considered to be ‘failed stars’ in the sense that they are born with masses between the least massive stars (0.072 solar masses, M⊙)1 and the most massive planets (∼0.013M⊙)2; they therefore serve as a critical link in our understanding of the formation of both stars and planets3. Even the most fundamental physical properties of brown dwarfs remain, however, largely unconstrained by direct measurement. Here we report the discovery of a brown-dwarf eclipsing binary system, in the Orion Nebula star-forming region, from which we obtain direct measurements of mass and radius for these newly formed brown dwarfs. Our mass measurements establish both objects as brown dwarfs, with masses of 0.054 ± 0.005M⊙ and 0.034 ± 0.003M⊙. At the same time, with radii relative to the Sun's of 0.669 ± 0.034R⊙ and 0.511 ± 0.026R⊙, these brown dwarfs are more akin to low-mass stars in size. Such large radii are generally consistent with theoretical predictions for young brown dwarfs in the earliest stages of gravitational contraction4,5. Surprisingly, however, we find that the less-massive brown dwarf is the hotter of the pair; this result is contrary to the predictions of all current theoretical models of coeval brown dwarfs.

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Figure 1: Light curve of 2MASS J05352184–0546085 at 0.8 µm.
Figure 2: Radial velocity measurements and orbit solution.
Figure 3: Near-infrared spectrum and colours of 2MASS J05352184–0546085.

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References

  1. Chabrier, G. & Baraffe, I. Theory of low-mass stars and substellar objects. Annu. Rev. Astron. Astrophys. 38, 337–377 (2000)

    Article  ADS  CAS  Google Scholar 

  2. Burrows, A., Hubbard, W. B., Lunine, J. I. & Liebert, J. The theory of brown dwarfs and extrasolar giant planets. Rev. Mod. Phys. 73, 719–765 (2001)

    Article  ADS  CAS  Google Scholar 

  3. Basri, G. Observations of brown dwarfs. Annu. Rev. Astron. Astrophys. 38, 485–519 (2000)

    Article  ADS  CAS  Google Scholar 

  4. Baraffe, I., Chabrier, G., Allard, F. & Hauschildt, P. H. Evolutionary models for solar metallicity low-mass stars: mass-magnitude relationships and colour-magnitude diagrams. Astron. Astrophys. 337, 403–412 (1998)

    ADS  Google Scholar 

  5. D'Antona, F. & Mazzitelli, I. Evolution of low mass stars. Mem. Soc. Astron. It. 68, 807–822 (1997)

    ADS  CAS  Google Scholar 

  6. Zapatero Osorio, M. R. et al. Dynamical masses of the binary brown dwarf GJ 569 Bab. Astrophys. J. 615, 958–971 (2004)

    Article  ADS  Google Scholar 

  7. Andersen, J. Accurate masses and radii of normal stars. Astron. Astrophys. Rev. 3, 91–126 (1991)

    Article  ADS  Google Scholar 

  8. Wilson, R. E. & Devinney, E. J. Realization of accurate close-binary light curves: application to MR Cygni. Astrophys. J. 166, 605–620 (1971)

    Article  ADS  Google Scholar 

  9. Prsa, A. & Zwitter, T. A computational guide to physics of eclipsing binaries. I. Demonstrations and perspectives. Astrophys. J. 628, 426–438 (2005)

    Article  ADS  Google Scholar 

  10. Chabrier, G., Baraffe, I., Allard, F. & Hauschildt, P. Evolutionary models for very low-mass stars and brown dwarfs with dusty atmospheres. Astrophys. J. 542, 464–472 (2000)

    Article  ADS  CAS  Google Scholar 

  11. Scholz, A. & Eisloffel, J. Rotation and variability of very low mass stars and brown dwarfs near epsilon Ori. Astron. Astrophys. 429, 1007–1023 (2005)

    Article  ADS  Google Scholar 

  12. Mohanty, S. & Basri, G. Rotation and activity in mid-M to L field dwarfs. Astrophys. J. 583, 451–472 (2003)

    Article  ADS  Google Scholar 

  13. Stassun, K. G., Mathieu, R. D., Vaz, L. P. R., Stroud, N. & Vrba, F. J. Dynamical mass constraints on low-mass pre-main-sequence stellar evolutionary tracks: an eclipsing binary in Orion with a 1.0 M⊙ primary and a 0.7 M⊙ secondary. Astrophys. J. Suppl. 151, 357–385 (2004)

    Article  ADS  CAS  Google Scholar 

  14. Bessell, M. S. The late-M dwarfs. Astron. J. 101, 662–676 (1991)

    Article  ADS  CAS  Google Scholar 

  15. Slesnick, C. L., Hillenbrand, L. A. & Carpenter, J. M. The spectroscopically determined substellar mass function of the Orion Nebula cluster. Astrophys. J. 610, 1045–1063 (2004)

    Article  ADS  CAS  Google Scholar 

  16. Hillenbrand, L. A. & White, R. J. An assessment of dynamical mass constraints on pre-main-sequence evolutionary tracks. Astrophys. J. 604, 741–757 (2004)

    Article  ADS  CAS  Google Scholar 

  17. Carpenter, J. M., Hillenbrand, L. A. & Skrutskie, M. F. Near-infrared photometric variability of stars toward the Orion A molecular cloud. Astron. J. 121, 3160–3190 (2001)

    Article  ADS  Google Scholar 

  18. Genzel, R. & Stutzki, J. The Orion molecular cloud and star-forming region. Annu. Rev. Astron. Astrophys. 27, 41–85 (1989)

    Article  ADS  CAS  Google Scholar 

  19. Sicilia-Aguilar, A. et al. Accretion, kinematics, and rotation in the Orion Nebula Cluster: Initial results from Hectochelle. Astron. J. 129, 363–381 (2005)

    Article  ADS  CAS  Google Scholar 

  20. Hillenbrand, L. A. On the stellar population and star-forming history of the Orion Nebula Cluster. Astron. J. 113, 1733–1768 (1997)

    Article  ADS  CAS  Google Scholar 

  21. Palla, F. & Stahler, S. W. Star formation in the Orion Nebula Cluster. Astrophys. J. 525, 772–783 (1999)

    Article  ADS  Google Scholar 

  22. Pont, F. et al. A planet-sized transiting star around OGLE-TR-122. Accurate mass and radius near the hydrogen-burning limit. Astron. Astrophys. 433, L21–L24 (2005)

    Article  ADS  CAS  Google Scholar 

  23. Reipurth, B. & Clarke, C. The formation of brown dwarfs as ejected stellar embryos. Astron. J. 122, 432–439 (2001)

    Article  ADS  Google Scholar 

  24. Bate, M. R. & Bonnell, I. A. The origin of the initial mass function and its dependence on the mean Jeans mass in molecular clouds. Mon. Not. R. Astron. Soc. 356, 1201–1221 (2005)

    Article  ADS  Google Scholar 

  25. Bate, M. R., Bonnell, I. A. & Bromm, V. The formation mechanism of brown dwarfs. Mon. Not. R. Astron. Soc. 332, L65–L68 (2002)

    Article  ADS  Google Scholar 

  26. Maxted, P. F. L. & Jeffries, R. D. On the frequency of close binary systems among very low-mass stars and brown dwarfs. Mon. Not. R. Astron. Soc. 362, L45–L49 (2005)

    Article  ADS  Google Scholar 

  27. Mohanty, S., Jayawardhana, R. & Basri, G. Measuring fundamental parameters of substellar objects. II. Masses and radii. Astrophys. J. 609, 885–905 (2004)

    Article  ADS  Google Scholar 

  28. Mohanty, S. et al. Measuring fundamental parameters of substellar objects. I. Surface gravities. Astrophys. J. 609, 854–884 (2004)

    Article  ADS  CAS  Google Scholar 

  29. Doppmann, G. W. & Jaffe, D. T. A spectroscopic technique for measuring stellar properties of pre-main-sequence stars. Astron. J. 126, 3030–3042 (2003)

    Article  ADS  CAS  Google Scholar 

  30. Doppmann, G. W., Jaffe, D. T. & White, R. J. Stellar properties of pre-main-sequence stars from high-resolution near-infrared spectra. Astron. J. 126, 3043–3057 (2003)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We are grateful to I. Baraffe, G. Basri, D. Golimowski, and D. Weintraub for discussions, and to D. Gudehaus and A. Prsa for software used in our analyses. This work is supported by grants to K.G.S. and R.D.M. from the National Science Foundation. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

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Authors and Affiliations

  1. Department of Physics and Astronomy, Vanderbilt University, Tennessee, 37235, Nashville, USA

    Keivan G. Stassun

  2. Department of Astronomy, University of Wisconsin—Madison, Wisconsin, 53706, Madison, USA

    Robert D. Mathieu

  3. Space Telescope Science Institute, Maryland, 21218, Baltimore, USA

    Jeff A. Valenti

Authors
  1. Keivan G. Stassun
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  2. Robert D. Mathieu
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Correspondence to Keivan G. Stassun.

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Supplementary information

Supplementary Figure 1

The geometry of the orbit is shown both as it appears from Earth and as it would appear if seen from above, at four different times in the orbit. Also shown is the relationship between the orbital geometry and the diminutions of light that occur when the brown dwarfs eclipse one another. (PDF 142 kb)

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Stassun, K., Mathieu, R. & Valenti, J. Discovery of two young brown dwarfs in an eclipsing binary system. Nature 440, 311–314 (2006). https://doi.org/10.1038/nature04570

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