Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A global cloud map of the nearest known brown dwarf

Abstract

Brown dwarfs—substellar bodies more massive than planets but not massive enough to initiate the sustained hydrogen fusion that powers self-luminous stars1,2—are born hot and slowly cool as they age. As they cool below about 2,300 kelvin, liquid or crystalline particles composed of calcium aluminates, silicates and iron condense into atmospheric ‘dust’3,4, which disappears at still cooler temperatures (around 1,300 kelvin)5,6. Models to explain this dust dispersal include both an abrupt sinking of the entire cloud deck into the deep, unobservable atmosphere5,7 and breakup of the cloud into scattered patches6,8 (as seen on Jupiter and Saturn9). However, hitherto observations of brown dwarfs have been limited to globally integrated measurements10, which can reveal surface inhomogeneities but cannot unambiguously resolve surface features11. Here we report a two-dimensional map of a brown dwarf’s surface that allows identification of large-scale bright and dark features, indicative of patchy clouds. Monitoring suggests that the characteristic timescale for the evolution of global weather patterns is approximately one day.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: High-resolution, near-infrared spectra of the Luhman 16AB brown dwarfs (black curves).
Figure 2: Surface map of brown dwarf Luhman 16B.

References

  1. 1

    Kumar, S. S. The structure of stars of very low mass. Astrophys. J. 137, 1121–1125 (1963)

    ADS  Article  Google Scholar 

  2. 2

    Becklin, E. E. & Zuckerman, B. A low-temperature companion to a white dwarf star. Nature 336, 656–658 (1988)

    ADS  Article  Google Scholar 

  3. 3

    Lunine, J. I., Hubbard, W. B. & Marley, M. S. Evolution and infrared spectra of brown dwarfs. Astrophys. J. 310, 238–260 (1986)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Kirkpatrick, J. D. et al. Dwarfs cooler than “M”: the definition of spectral type “L” using discoveries from the 2 Micron All-Sky Survey (2MASS). Astrophys. J. 519, 802–833 (1999)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Stephens, D. C. et al. The 0.8–14.5 μm spectra of mid-L to mid-T dwarfs: diagnostics of effective temperature, grain sedimentation, gas transport, and surface gravity. Astrophys. J. 702, 154–170 (2009)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Burgasser, A. J. et al. Evidence of cloud disruption in the L/T dwarf transition. Astrophys. J. 571, L151–L154 (2002)

    ADS  Article  Google Scholar 

  7. 7

    Tsuji, T., Nakajima, T. & Yanagisawa, K. Dust in the photospheric environment. II. Effect on the near-infrared spectra of L and T dwarfs. Astrophys. J. 607, 511–529 (2004)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Ackerman, A. S. & Marley, M. S. Precipitating condensation clouds in substellar atmospheres. Astrophys. J. 556, 872–884 (2001)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Fletcher, L. N. et al. Retrievals of atmospheric variables on the gas giants from ground-based mid-infrared imaging. Icarus 200, 154–175 (2009)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Buenzli, E. et al. Vertical atmospheric structure in a variable brown dwarf: pressure-dependent phase shifts in simultaneous Hubble Space Telescope-Spitzer light curves. Astrophys. J. 760, L31–L36 (2012)

    ADS  Article  Google Scholar 

  11. 11

    Apai, D. et al. HST spectral mapping of L/T transition brown dwarfs reveals cloud thickness variations. Astrophys. J. 768, 121–136 (2013)

    ADS  Article  Google Scholar 

  12. 12

    Luhman, K. L. Discovery of a binary brown dwarf at 2 pc from the Sun. Astrophys. J. 767, L1–L6 (2013)

    ADS  Article  Google Scholar 

  13. 13

    Kniazev, A. Y. et al. Characterization of the nearby L/T binary brown dwarf WISE J104915.57–531906.1 at 2 pc from the Sun. Astrophys. J. 770, 124–128 (2013)

    ADS  Article  Google Scholar 

  14. 14

    Burgasser, A. J., Sheppard, S. S. & Luhman, K. L. Resolved near-infrared spectroscopy of WISE J104915.57–531906.1AB: a flux-reversal binary at the L dwarf/T dwarf transition. Astrophys. J. 772, 129–135 (2013)

    ADS  Article  CAS  Google Scholar 

  15. 15

    Gillon, M. et al. Fast-evolving weather for the coolest of our two new substellar neighbours. Astron. Astrophys. 555, L5–L8 (2013)

    ADS  Article  Google Scholar 

  16. 16

    Käufl, H.-U. et al. CRIRES: a high-resolution infrared spectrograph for ESO's VLT. Proc. SPIE 5492, 1218–1227 (2004)

    ADS  Article  Google Scholar 

  17. 17

    Burrows, A., Heng, K. & Nampaisarn, T. The dependence of brown dwarf radii on atmospheric metallicity and clouds: theory and comparison with observations. Astrophys. J. 736, 47–60 (2011)

    ADS  Article  CAS  Google Scholar 

  18. 18

    Biller, B. A. et al. Weather on the nearest brown dwarfs: resolved simultaneous multi-wavelength variability monitoring of WISE J104915.57–531906.1AB. Astrophys. J. 778, L10–L16 (2013)

    ADS  Article  Google Scholar 

  19. 19

    Wheelwright, H. E., Vink, J. S., Oudmaijer, R. D. & Drew, J. E. On the alignment between the circumstellar disks and orbital planes of Herbig Ae/Be binary systems. Astron. Astrophys. 532, A28 (2011)

    ADS  Article  Google Scholar 

  20. 20

    Vogt, S. S., Penrod, G. D. & Hatzes, A. P. Doppler images of rotating stars using maximum entropy image reconstruction. Astrophys. J. 321, 496–515 (1987)

    ADS  Article  Google Scholar 

  21. 21

    Rice, J. B., Wehlau, W. H. & Khokhlova, V. L. Mapping stellar surfaces by Doppler imaging—technique and application. Astron. Astrophys. 208, 179–188 (1989)

    ADS  CAS  Google Scholar 

  22. 22

    Agúndez, M. et al. The impact of atmospheric circulation on the chemistry of the hot Jupiter HD 209458b. Astron. Astrophys. 548, A73 (2012)

    Article  CAS  Google Scholar 

  23. 23

    Cho, J. Y.-K., Menou, K., Hansen, B. M. S. & Seager, S. The changing face of the extrasolar giant planet HD 209458b. Astrophys. J. 587, L117–L120 (2003)

    ADS  Article  Google Scholar 

  24. 24

    Showman, A. P. & Kaspi, Y. Atmospheric dynamics of brown dwarfs and directly imaged giant planets. Astrophys. J. 776, 85–103 (2013)

    ADS  Article  CAS  Google Scholar 

  25. 25

    Vasavada, A. R. & Showman, A. P. Jovian atmospheric dynamics: an update after Galileo and Cassini. Rep. Prog. Phys. 68, 1935–1996 (2005)

    ADS  MathSciNet  Article  Google Scholar 

  26. 26

    Freytag, B., Allard, F., Ludwig, H.-G., Homeier, D. & Steffen, M. Radiation-hydrodynamics simulations of cool stellar and substellar atmospheres. ASP Conf. Ser. 448, 855–862 (2011)

    ADS  Google Scholar 

  27. 27

    Collier Cameron, A. & Unruh, Y. C. Doppler Images of AB Doradus. Mon. Not. R. Astron. Soc. 269, 814–836 (1995)

    ADS  Article  Google Scholar 

  28. 28

    Artigau, É., Donati, J.-F. & Delfosse, X. Planet detection, magnetic field of protostars and brown dwarfs meteorology with SPIRou. ASP Conf. Ser. 448, 771–778 (2011)

    ADS  Google Scholar 

  29. 29

    Majeau, C., Agol, E. & Cowan, N. B. A two-dimensional infrared map of the extrasolar planet HD 189733b. Astrophys. J. 747, L20–L24 (2012)

    ADS  Article  Google Scholar 

  30. 30

    de Wit, J., Gillon, M., Demory, B.-O. & Seager, S. Towards consistent mapping of distant worlds: secondary-eclipse scanning of the exoplanet HD 189733b. Astron. Astrophys. 548, A128 (2012)

    Article  Google Scholar 

  31. 31

    Blake, C. H., Charbonneau, D., White, R. J., Marley, M. S. & Saumon, D. Multiepoch radial velocity observations of L dwarfs. Astrophys. J. 666, 1198–1204 (2007)

    ADS  CAS  Article  Google Scholar 

  32. 32

    Bean, J. L. et al. The CRIRES search for planets around the lowest-mass stars. I. High-precision near-infrared radial velocities with an ammonia gas cell. Astrophys. J. 713, 410–422 (2010)

    ADS  CAS  Article  Google Scholar 

  33. 33

    Hinkle, K. H., Wallace, L. & Livingston, W. Atmospheric transmission above Kitt Peak, 0.5 to 5.5 microns. Bull. Am. Astron. Soc. 35, 1260 (2003) </cit-tl>

    Google Scholar 

  34. 34

    Allard, F., Homeier, D., Freytag, B., Schaffenberger, W. & Rajpurohit, A. S. Progress in modeling very low mass stars, brown dwarfs, and planetary mass objects. Mem. Soc. Astron. Ital. 24, (Suppl.), 128–139 2013)

    ADS  Google Scholar 

  35. 35

    Grey, D. F. The Observation and Analysis of Stellar Photospheres 3rd edn, Ch. 18 (Cambridge Univ. Press, 2005)

    Book  Google Scholar 

  36. 36

    Jones, H. R. A. et al. Carbon monoxide in low-mass dwarf stars. Mon. Not. R. Astron. Soc. 358, 105–112 (2005)

    ADS  CAS  Article  Google Scholar 

  37. 37

    Schweitzer, A. et al. Effective temperatures of late L dwarfs and the onset of methane signatures. Astrophys. J. 566, 435–441 (2002)

    ADS  CAS  Article  Google Scholar 

  38. 38

    Konopacky, Q. M. et al. High-precision dynamical masses of very low mass binaries. Astrophys. J. 711, 1087–1122 (2010)

    ADS  Article  Google Scholar 

  39. 39

    Dupuy, T. J. & Liu, M. C. On the distribution of orbital eccentricities for very low-mass binaries. Astrophys. J. 733, 122–135 (2011)

    ADS  Article  Google Scholar 

  40. 40

    Donati, J.-F., Semel, M., Carter, B. D., Rees, D. E. & Collier Cameron, A. Spectropolarimetric observations of active stars. Mon. Not. R. Astron. Soc. 291, 658–682 (1997)

    ADS  Article  Google Scholar 

  41. 41

    Foreman-Mackey, D., Hogg, D. W., Lang, D. & Goodman, J. emcee: The MCMC hammer. Publ. Astron. Soc. Pacif. 125, 306–312 (2013)

    ADS  Article  Google Scholar 

  42. 42

    Vogt, S. S. Doppler images of spotted late-type stars. In The Impact of Very High S/N Spectroscopy on Stellar Physics 253–272 (Proc. 132nd Symp. Int. Astron. Union, 1988).

    ADS  Article  Google Scholar 

  43. 43

    Narayan, R. & Nityananda, R. Maximum entropy image restoration in astronomy. Annu. Rev. Astron. Astrophys. 24, 127–170 (1986)

    ADS  Article  Google Scholar 

  44. 44

    Rice, J. B. Doppler imaging of stellar surfaces—techniques and issues. Astron. Nachr. 323, 220–235 (2002)

    ADS  CAS  Article  Google Scholar 

  45. 45

    Rice, J. B. & Strassmeier, K. G. Doppler imaging from artificial data. Testing the temperature inversion from spectral-line profiles. Astron. Astrophys. 147 (Suppl.). 151–168 (2000)

    ADS  Google Scholar 

  46. 46

    Unruh, Y. C. & Collier Cameron, A. The sensitivity of Doppler imaging to line profile models. Mon. Not. R. Astron. Soc. 273, 1–16 (1995)

    ADS  Article  Google Scholar 

  47. 47

    Freytag, B., Allard, F., Ludwig, H.-G., Homeier, D. & Steffen, M. The role of convection, overshoot, and gravity waves for the transport of dust in M dwarf and brown dwarf atmospheres. Astron. Astrophys. 513, A19 (2010)

    Article  Google Scholar 

  48. 48

    Draegert, D. A. & Williams, D. Collisional broadening of CO absorption lines by foreign gases. J. Opt. Soc. Am. 58, 1399–1403 (1968)

    ADS  CAS  Article  Google Scholar 

  49. 49

    Bouanich, J. Détermination expérimentale des largeurs et des déplacements des raies de la bande 0 → 2 de co pertubé par les gaz rares (He, Ne, Ar, Kr, Xe). J. Quant. Spec. Radiat. Transf. 12, 1609–1615 (1972)

    ADS  CAS  Article  Google Scholar 

  50. 50

    Malathy Devi, V. et al. Spectral line parameters including temperature dependences of self- and air-broadening in the 2 → 0 band of CO at 2.3 micron. J. Quant. Spec. Radiat. Transf. 113, 1013–1033 (2012)

    ADS  CAS  Article  Google Scholar 

  51. 51

    Faure, A., Wiesenfeld, L., Drouin, B. J. & Tennyson, J. Pressure broadening of water and carbon monoxide transitions by molecular hydrogen at high temperatures. J. Quant. Spec. Radiat. Transf. 116, 79–86 (2013)

    ADS  CAS  Article  Google Scholar 

  52. 52

    Predoi-Cross, A., Bouanich, J. P., Benner, D. C., May, A. D. & Drummond, J. R. Broadening, shifting, and line asymmetries in the 2 ← 0 band of CO and CO–N2: experimental results and theoretical calculations. J. Chem. Phys. 113, 158–168 (2000)

    ADS  CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank A. Hatzes for advice on Doppler imaging analysis, J. Smoker for helping to plan and execute our observations and E. Mills for help in designing figures. This work is based on Director’s Discretionary observations made with the European Southern Observatory Telescopes at the Paranal Observatory under programme ID 291.C-5006(A); data are available in the European Southern Observatory Data Archive at http://archive.eso.org/. D.H. received support from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013 Grant Agreement number 247060). M.B., D.H. and F.A. acknowledge support from the French National Research Agency (ANR) through project grant ANR10-BLANC0504-01. E.B. is supported by the Swiss National Science Foundation (SNSF). Atmosphere models have been computed on the Pôle Scientifique de Modélisation Numérique at the Ecole Normale Supérieure (ENS) de Lyon, and at the Gesellschaft für Wissenschaftliche Datenverarbeitung Göttingen in co-operation with the Institut für Astrophysik Göttingen. IRAF (the Image Reduction and Analysis Facility) is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. PyRAF (Python-based IRAF) is a product of the Space Telescope Science Institute, which is operated by AURA for NASA. We also thank contributors to SciPy, Matplotlib, AstroPy and the Python programming language.

Author information

Affiliations

Authors

Contributions

I.J.M.C. coordinated the project and conducted all analyses. I.J.M.C., B.B., J.E.S., N.R.D., M.B., W.B., B.G. and T.K. assisted in obtaining the spectroscopic observations. I.J.M.C., B.B., J.E.S., N.R.D., M.B., D.H., F.A., E.B., Th.H. and W.B. contributed to the manuscript. J.E.S. provided an independent analysis of the projected rotational velocity and radial velocity of both brown dwarfs. B.B. and N.R.D. provided advice on binary dynamics. D.H. and F.A. provided advice on brown dwarf atmospheric processes and the spectral models used for the data calibration, least squares deconvolution and Doppler imaging.

Corresponding author

Correspondence to I. J. M. Crossfield.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Spectral calibration for Luhman 16A (a and b) and Luhman 16B (c and d).

The red curves (a and c) show the modelled spectra, which mostly overlap the observed spectra (plotted in black). The gaps in the spectra correspond to physical spaces between the four infrared array detectors. The residuals to the fits (b and d) are generally a few per cent, with larger deviations apparent near CO bandheads (for example, at 2.294 µm and 2.323 µm) and strong telluric absorption lines (for example, at 2.290 µm and 2.340 µm).

Extended Data Figure 2 Calibrated spectra of the brown dwarfs, showing the individual calibrated spectra of Luhman 16A (a) and Luhman 16B (b).

The time of each observation is indicated.

Extended Data Figure 3 Luhman 16B shows strong rotationally induced variability (b) whereas Luhman 16A does not (a).

The colour scale indicates the deviations from a uniform line profile as measured relative to the line continuum. Luhman 16B’s variations are dominated by a dark region (diagonal streak, corresponding to a decrease of roughly 4% in equivalent width) that comes into view at 1.5 h heading towards the observer, rotates across the brown dwarf to the receding side, and is again hidden behind the limb at 3 h. Brighter regions are visible at earlier and later times, but are less prominent. No significant spectroscopic variability is apparent for Luhman 16A, and no coherent features are seen beyond Luhman 16B’s projected rotational velocity (enclosed between the vertical dashed lines). All these points indicate that we are detecting intrinsic spectroscopic variability from Luhman 16B.

Extended Data Figure 4 Posterior parameter distributions from our single-spot toy model, showing a large mid-latitude spot.

The inner and outer curves in panels ac indicate the 68.3% and 95.4% confidence regions. The plot shown assumes i = 30 degrees; smaller inclinations result in a slightly more equatorial spot, but the best-fit values remain within the inner 68.3% confidence regions.

Extended Data Figure 5 Simulated brown dwarf with spots, and the map recovered from Doppler imaging.

a, Simulated variable brown dwarf seen at an inclination of i = 30 degrees. The dark and light mid-latitude spots are, respectively, 40% darker and 10% brighter than the photosphere; the dark streak is 10% darker and the polar spot is 20% brighter. b, Surface map recovered from Doppler imaging, assuming noise levels similar to that seen in our observed data, after tuning the hyperparameter a to minimize spurious features. High-contrast features are recovered: the dark spot is in the correct location and the polar spot is only moderately distorted. The equatorial bright spot is visible in the recovered map, but it cannot be reliably distinguished from image artefacts that preferentially cluster near the equator. The dark stripe is not recovered. Thus our analysis can accurately recover strong features, but data quality precludes us from discerning smaller or fainter features.

Extended Data Figure 6 Simulated brown dwarf with spots and bands, and the map recovered from Doppler imaging.

a, Simulated variable brown dwarf with the same surface features as in Extended Data Fig. 5, but now also exhibiting zonal bands with an amplitude of ±20% of the mean photospheric brightness level. b, Surface map recovered from Doppler imaging under the same assumptions as in Extended Data Fig. 5. High-contrast, non-axisymmetric features are recovered as before, but we cannot recover even prominent global bands with the current precision of our data.

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Crossfield, I., Biller, B., Schlieder, J. et al. A global cloud map of the nearest known brown dwarf. Nature 505, 654–656 (2014). https://doi.org/10.1038/nature12955

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links