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Fast spin of the young extrasolar planet β Pictoris b



The spin of a planet arises from the accretion of angular momentum during its formation1,2,3, but the details of this process are still unclear. In the Solar System, the equatorial rotation velocities and, consequently, spin angular momenta of most of the planets increase with planetary mass4; the exceptions to this trend are Mercury and Venus, which, since formation, have significantly spun down because of tidal interactions5,6. Here we report near-infrared spectroscopic observations, at a resolving power of 100,000, of the young extrasolar gas giant planet β Pictoris b (refs 7, 8). The absorption signal from carbon monoxide in the planet’s thermal spectrum is found to be blueshifted with respect to that from the parent star by approximately 15 kilometres per second, consistent with a circular orbit9. The combined line profile exhibits a rotational broadening of about 25 kilometres per second, meaning that β Pictoris b spins significantly faster than any planet in the Solar System, in line with the extrapolation of the known trend in spin velocity with planet mass.

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Figure 1: Broadened cross-correlation signal of β Pictoris b.
Figure 2: Spin of β Pictoris b.

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  1. Lissauer, J. J. & Kary, D. M. The origin of the systematic component of planetary rotation: I. Planet on a circular orbit. Icarus 94, 126–159 (1991)

    Article  ADS  Google Scholar 

  2. Dones, L. & Tremaine, S. On the origin of planetary spins. Icarus 103, 67–92 (1993)

    Article  ADS  Google Scholar 

  3. Johansen, A. & Lacerda, P. Prograde rotation of protoplanets by accretion of pebbles in a gaseous environment. Mon. Not. R. Astron. Soc. 404, 475–485 (2010)

    ADS  Google Scholar 

  4. Hughes, D. W. Planetary spin. Planet. Space Sci. 51, 517–523 (2003)

    Article  ADS  Google Scholar 

  5. Pettengill, G. H. & Dyce, R. B. A Radar determination of the rotation of the planet Mercury. Nature 206, 1240 (1965)

    Article  ADS  Google Scholar 

  6. Correia, A. C. M. & Laskar, J. The four final rotation states of Venus. Nature 411, 767–770 (2001)

    Article  CAS  ADS  Google Scholar 

  7. Lagrange, A.-M. et al. A probable giant planet imaged in the β Pictoris disk. Astron. Astrophys. 493, L21–L25 (2009)

    Article  ADS  Google Scholar 

  8. Lagrange, A.-M. et al. A giant planet imaged in the disk of the young star Pictoris. Science 329, 57–59 (2010)

    Article  CAS  ADS  Google Scholar 

  9. Chauvin, G. et al. Orbital characterization of the β Pictoris b giant planet. Astron. Astrophys. 542, A41 (2012)

    Article  Google Scholar 

  10. Brogi, M. et al. The signature of orbital motion from the dayside of the planet τ Bootis b. Nature 486, 502–504 (2012)

    Article  CAS  ADS  Google Scholar 

  11. de Kok, R. et al. Detection of carbon monoxide in the high-resolution day-side spectrum of the exoplanet HD 189733b. Astron. Astrophys. 554, A82 (2013)

    Article  Google Scholar 

  12. Sparks, W. B. & Ford, H. C. Imaging spectroscopy for extrasolar planet detection. Astrophys. J. 578, 543 (2002)

    Article  ADS  Google Scholar 

  13. Konopacky, Q. M., Barman, T. S., Macintosh, B. A. & Marois, C. Detection of carbon monoxide and water absorption lines in an exoplanet atmosphere. Science 339, 1398–1401 (2013)

    Article  CAS  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  15. Gontcharov, G. A. Pulkovo compilation of radial velocities for 35495 Hipparcos stars in a common system. Astron. Lett. 32, 759–771 (2006)

    Article  ADS  Google Scholar 

  16. Lecavelier Des Etangs, A. et al. β Pictoris: evidence of light variations. Astron. Astrophys. 299, 557 (1995)

    CAS  ADS  Google Scholar 

  17. Lecavelier Des Etangs, A. et al. Beta Pictoris light variations. I. The planetary hypothesis. Astron. Astrophys. 328, 311–320 (1997)

    ADS  Google Scholar 

  18. Cuk, M. & Stewart, S. Making the Moon from a fast-spinning Earth: a giant impact followed by resonant despinning. Science 338, 1047–1052 (2012)

    Article  CAS  ADS  Google Scholar 

  19. Currie, T. et al. A combined Very Large Telescope and Gemini study of the atmosphere of the directly imaged planet, β Pictoris b. Astrophys. J. 776, 15 (2013)

    Article  ADS  Google Scholar 

  20. Bonnefoy, M. et al. The near-infrared spectral energy distribution of β Pictoris b. Astron. Astrophys. 555, A107 (2013)

    Article  Google Scholar 

  21. Binks, A. S. & Jeffries, R. D. A lithium depletion boundary age of 21 Myr for the Beta Pictoris moving group. Mon. Not. R. Astron. Soc. 438, L11–L15 (2014)

    Article  CAS  ADS  Google Scholar 

  22. Konopacky, Q. M. et al. Rotational velocities of individual components in very low mass binaries. Astrophys. J. 750, 79–93 (2012)

    Article  ADS  Google Scholar 

  23. Crossfield, I. et al. A global cloud map of the nearest known brown dwarf. Nature 505, 654–656 (2014)

    Article  CAS  ADS  Google Scholar 

  24. Baraffe, I., Chabrier, G., Barman, T. S., Allard, F. & Hauschildt, P. H. Evolutionary models for cool brown dwarfs and extrasolar giant planets. Astron. Astrophys. 402, 701–712 (2003)

    Article  ADS  Google Scholar 

  25. Arsenault, R. et al. MACAO-VLTI: an adaptive optics system for the ESO VLT interferometer. Adapt. Opt. Syst. Technol. II 4839, 174–185 (2003)

    Article  ADS  Google Scholar 

  26. Vogt, S. & Penrod, G. Doppler imaging of spotted stars: application to the RS Canum Venaticorum star HR 1099. Publ. Astron. Soc. Pacif. 95, 565–576 (1983)

    Article  CAS  ADS  Google Scholar 

  27. Vogt, S., Hatzes, A., Misch, A. & Kurster, M. Doppler imagery of the spotted RS Canum Venaticorum star HR 1099 (V711 Tauri) from 1981 to 1992. Astrophys. J. 121 (suppl.). 547–589 (1999)

    Article  CAS  ADS  Google Scholar 

  28. Barnes, J., Collier Cameron, A., James, D. & Donati, J.-F. Doppler images from dual-site observations of southern rapidly rotating stars – I. Differential rotation on PZ Tel. Mon. Not. R. Astron. Soc. 314, 162–174 (2000)

    Article  CAS  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  30. European. Southern Observatory. CRIRES data reduction pipeline (2011)

  31. Rucinski, S. in Precise Stellar Radial Velocities, IAU Colloquium. 170. (eds Hearnshaw, J. B. & Scarfe, C. D. ) 82–190 (Astronomical Society of the Pacific, 1999)

    Google Scholar 

  32. Brogi, M. et al. Detection of molecular absorption in the dayside of exoplanet 51 Pegasi b? Astrophys. J. 767, 27 (2013)

    Article  ADS  Google Scholar 

  33. Birkby, J. L. et al. Detection of water absorption in the day side atmosphere of HD 189733b using ground-based high-resolution spectroscopy at 3.2 μm. Mon. Not. R. Astron. Soc. 436, L35–L39 (2013)

    Article  CAS  ADS  Google Scholar 

  34. Borysow, A., Jorgensen, U. G. & Fu, Y. High-temperature (1000–7000 K) collision-induced absorption of H2 pairs computed from the first principles, with application to cool and dense stellar atmospheres. J. Quant. Spectrosc. Radiat. Transf. 68, 235–255 (2001)

    Article  CAS  ADS  Google Scholar 

  35. Borysow, A. Collision-induced absorption coefficients of H2 pairs at temperatures from 60 K to 1000 K. Astron. Astrophys. 390, 779 (2002)

    Article  ADS  Google Scholar 

  36. Madhusudhan, N. C/O ratio as a dimension for characterizing exoplanetary atmospheres. Astrophys. J. 758, 36 (2012)

    Article  ADS  Google Scholar 

  37. Moses, J. I., Madhusudhan, N., Visscher, C. & Freedman, R. S. Chemical consequences of the C/O ratio on hot Jupiters: examples from WASP-12b, CoRoT-2b, XO-1b, and HD 189733b. Astrophys. J. 763, 25 (2013)

    Article  ADS  Google Scholar 

  38. Rothman, L. S. et al. HITEMP, the high-temperature spectroscopic database. J. Quant. Spectrosc. Radiat. Transf. 111, 2139–2150 (2010)

    Article  CAS  ADS  Google Scholar 

  39. Rothman, L. S. et al. The HITRAN 2008 molecular spectroscopic database. J. Quant. Spectrosc. Radiat. Transf. 110, 533–572 (2009)

    Article  CAS  ADS  Google Scholar 

  40. Brandl, B. et al. METIS: the thermal infrared instrument for the E-ELT. Proc. SPIE 8446, 84461M (2012)

    Article  Google Scholar 

  41. Maiolino, R. et al. A community science case for E-ELT HIRES. Preprint at (2013)

  42. Lee, S. et al. GMTNIRS (Giant Magellan Telescope near-infrared spectrograph): design concept. Proc. SPIE 7735, 77352K (2010)

    Article  Google Scholar 

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We thank T. de Zeeuw for granting Director’s Discretionary Time on the VLT to perform these observations (292.C-5017(A)). I.A.G.S. acknowledges support from an NWO VICI grant. R.J.d.K. acknowledges the NWO PEPSci programme.

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Authors and Affiliations



I.A.G.S. designed the project with help from B.R.B., R.J.d.K., M.B. and J.B. The analysis was led by I.A.G.S. and he wrote the first version of the manuscript. I.A.G.S. and B.R.B. made the connection with the European Extremely Large Telescope. R.J.d.K. constructed the planet atmosphere models. B.J.B., R.J.d.K., M.B., J.B. and H.S. discussed the analyses and results, and commented on the manuscript.

Corresponding author

Correspondence to Ignas A. G. Snellen.

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The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Model spectra and cross-correlation signals.

The model spectral templates (left panels) and the resulting cross-correlation signals (right panels) for (from top to bottom) a high-VMR CO model, a low-VMR CO model, the previous model with an added high VMR of H2O, an H2O-only mode and a CH4 model. Atmospheric pressures are in units of bars.

Extended Data Figure 2 Simulated E-ELT observations.

We simulated observations of a rotating spot on β Pictoris b as would be made by the future 39-m European Extremely Large Telescope. Such observations could be conducted with the planned METIS40. The three panels on the left show the position of the spot at times approximately 1 h apart. The spot was given a surface brightness twice that of the rest of the planet’s atmosphere. The right-hand panel shows the difference between three cross-correlation signals with respect to the average cross-correlation profile as indicated by the dashed curve (scaled down by a factor of 25), with the spot signature moving from −15 to +5 km s−1.

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Snellen, I., Brandl, B., de Kok, R. et al. Fast spin of the young extrasolar planet β Pictoris b. Nature 509, 63–65 (2014).

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