Skip to main content

Thank you for visiting 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.

An early extrasolar planetary system revealed by planetesimal belts in β Pictoris


β Pictoris (β Pic) is a main-sequence star with an edge-on dust disk1,2,3 that might represent a state of the early Solar System. The dust does not seem to be a remnant from the original protoplanetary disk, but rather is thought to have been generated from large bodies like planetesimals and/or comets4,5. The history and composition of the parent bodies can therefore be revealed by determining the spatial distribution, grain size, composition and crystallinity of the dust through high-resolution mid-infrared observations. Here we report that the sub-micrometre amorphous silicate grains around β Pic have peaks in their distribution around 6, 16 and 30 au (1 au is the Sun–Earth distance), whereas the crystalline and micrometre-sized amorphous silicate grains are concentrated in the disk centre. As sub-micrometre grains are blown quickly out from the system by radiation pressure from the central star, the peaks indicate the locations of ongoing dust replenishment, which originates from ring-like distributions of planetesimals or ‘planetesimal belts’.

Your institute does not have access to this article

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Spectra of β Pic after subtraction of the photospheric emission.
Figure 2: Distribution of each dust emission.
Figure 3: Conceptual view of the discovered planetesimal belts.


  1. Gillett, F. C. in Light on Dark Matter (ed. Israel, F. P.) 61–69 (Reidel, Dordrecht, 1986)

    Book  Google Scholar 

  2. Smith, B. A. & Terrile, R. J. A circumstellar disk around Beta Pictoris. Science 226, 1421–1424 (1984)

    ADS  CAS  Article  Google Scholar 

  3. Pantin, E., Lagage, P. O. & Artymowicz, P. Mid-infrared images and models of the beta Pictoris dust disk. Astron. Astrophys. 327, 1123–1136 (1997)

    ADS  Google Scholar 

  4. Backman, D. E. & Paresce, F. in Protostars and Planets III (eds Levy, E. H. & Lunine, J. I.) 1253–1304 (Univ. Arizona Press, Tucson, 1993)

    Google Scholar 

  5. Lecavelier des Etangs, A., Vidal-Madjar, A. & Ferlet, R. Dust distribution in disks supplied by small bodies: is the β Pictoris disk a gigantic multi-cometary tail? Astron. Astrophys. 307, 542–550 (1996)

    ADS  CAS  Google Scholar 

  6. Crifo, F., Vidal-Madjar, A., Lallement, R., Ferlet, R. & Gerbaldi, M. β Pictoris revisited by Hipparcos. Star properties. Astron. Astrophys. 320, L29–L32 (1997)

    ADS  Google Scholar 

  7. Barrado y Navascues, D., Stauffer, J. R., Song, I. & Caillault, J.-P. The age of beta Pictoris. Astrophys. J. 520, L123–L126 (1999)

    ADS  Article  Google Scholar 

  8. Wahhaj, Z. et al. The inner rings of β Pictoris. Astrophys. J. 584, L27–L31 (2003)

    ADS  Article  Google Scholar 

  9. Malfait, K. et al. The spectrum of the young star HD100546 observed with the Infrared Space Observatory. Astron. Astrophys. 332, L25–L28 (1998)

    ADS  Google Scholar 

  10. Honda, M. et al. Detection of crystalline silicates around T Tauri star Hen3–600A. Astrophys. J. 585, L59–L63 (2003)

    ADS  CAS  Article  Google Scholar 

  11. Campins, H. & Ryan, E. V. The identification of crystalline olivine in cometary silicates. Astrophys. J. 341, 1059–1066 (1989)

    ADS  CAS  Article  Google Scholar 

  12. Knacke, R. F. et al. The silicates in the disk of beta Pictoris. Astrophys. J. 418, 440–450 (1993)

    ADS  CAS  Article  Google Scholar 

  13. Hallenbeck, S. L., Nuth, J. A. III & Nelson, R. N. Evolving optical properties of annealing silicate grains: from amorphous condensate to crystalline mineral. Astrophys. J. 535, 247–255 (2000)

    ADS  CAS  Article  Google Scholar 

  14. Kataza, H. et al. COMICS: the cooled mid-infrared camera and spectrometer for the Subaru telescope. Proc. SPIE 4008, 1144–1152 (2000)

    ADS  Article  Google Scholar 

  15. Okamoto, Y. K. et al. Improved performances and capabilities of the Cooled Mid-Infrared Camera and Spectrometer (COMICS) for the Subaru Telescope. Proc. SPIE 4841, 169–180 (2003)

    ADS  Article  Google Scholar 

  16. Sako, S. et al. Improvements in operating the Raytheon 320x240 pixel Si:As impurity band conduction mid-infrared array. Publ. Astron. Soc. Pacif. 115, 1407–1418 (2003)

    ADS  Article  Google Scholar 

  17. Koike, C. et al. Compositional dependence of infrared absorption spectra of crystalline silicate II. Natural and synthetic olivines. Astron. Astrophys. 399, 1101–1107 (2003)

    ADS  CAS  Article  Google Scholar 

  18. Dorschner, J., Begemann, B., Henning, Th., Jäger, C. & Mutschke, H. Steps toward interstellar silicate mineralogy. II. Study of Mg-Fe-silicate glasses of variable composition. Astron. Astrophys. 300, 503–520 (1995)

    ADS  CAS  Google Scholar 

  19. Artymowicz, P. Radiation pressure forces on particles in the Beta Pictoris system. Astrophys. J. 335, L79–L82 (1988)

    ADS  CAS  Article  Google Scholar 

  20. Mukai, T. & Giese, R. H. Modification of the spatial distribution of interplanetary dust grains by Lorentz forces. Astron. Astrophys. 131, 355–363 (1984)

    ADS  Google Scholar 

  21. Fabian, D., Jäger, C., Henning, Th., Dorschner, J. & Mutschke, H. Steps toward interstellar silicate mineralogy V. Thermal evolution of amorphous magnesium silicates and silica. Astron. Astrophys. 364, 282–292 (2000)

    ADS  CAS  Google Scholar 

  22. Pantin, E., Waelkens, C. & Malfait, K. The Universe as Seen by ISO (eds Cox, P. & Kessler, M. F.) 385–388 (ESA SP 427, ESA Publications Division, Noordwijk, 1999)

    Google Scholar 

  23. Fixsen, D. J. & Dwek, E. The zodiacal emission spectrum as determined by COBE and its implications. Astrophys. J. 578, 1009–1014 (2002)

    ADS  Article  Google Scholar 

  24. Backman, D. E., Witteborn, F. C. & Gillett, F. C. Infrared observations and thermal models of the Beta Pictoris disk. Astrophys. J. 385, 670–679 (1992)

    ADS  Article  Google Scholar 

  25. Weinberger, A. J., Becklin, E. E. & Zuckerman, B. The first spatially resolved mid-infrared spectroscopy of β Pictoris. Astrophys. J. 584, L33–L37 (2003)

    ADS  CAS  Article  Google Scholar 

Download references


This Letter is based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. We thank C. Koike, I. Yamamura, F. Usui, S. Hasegawa, T. Ootsubo, H. Chihara, T. Nakamoto, H. Tanaka and T. Takeuchi for comments and discussions.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Yoshiko Kataza Okamoto.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Okamoto, Y., Kataza, H., Honda, M. et al. An early extrasolar planetary system revealed by planetesimal belts in β Pictoris. Nature 431, 660–663 (2004).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


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.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing