Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt
Artikel i vetenskaplig tidskrift, 2012

Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets(1). Collisions between such bodies produce small dust particles(2), the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg2-2xFe2xSiO4) has been done for the protoplanetary disk HD 100546 (refs 3, 4) and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids(5,6) (x approximate to 0.29). In the cold outskirts of the beta Pictoris system, an analogue to the young Solar System, olivine crystals were detected(7) but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets(8,9). Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of beta Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15-45 astronomical units from the star (one astronomical unit is the Sun-Earth distance), determine their magnesium-rich composition (x = 0.01 +/- 0.001) and show that they make up 3.6 +/- 1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System(8-10), even though beta Pictoris is more massive and more luminous and has a different planetary system architecture.





hd 100546

debris disks


protoplanetary disks




B. L. de Vries

KU Leuven

B. Acke

KU Leuven

Jadl Blommaert

KU Leuven

C. Waelkens

KU Leuven

Lbfm Waters

Anton Pannekoek Institute for Astronomy

Netherlands Institute for Space Research (SRON)

B. Vandenbussche

KU Leuven

M. Min

Anton Pannekoek Institute for Astronomy

G. Olofsson

Stockholms universitet

C. Dominik

Radboud Universiteit

Anton Pannekoek Institute for Astronomy

L. Decin

Anton Pannekoek Institute for Astronomy

KU Leuven

M. J. Barlow

University College London (UCL)

A. Brandeker

Stockholms universitet

J. Di Francesco

National Research Council Canada

A. M. Glauser

Royal Observatory

Eidgenössische Technische Hochschule Zürich (ETH)

J. S. Greaves


P. M. Harvey

The University of Texas at Austin

W. S. Holland

University of Edinburgh

Royal Observatory

R. J. Ivison

Royal Observatory

René Liseau

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

E. Pantin

CNRS Centre National de la Recherche Scientifique

G.L. Pilbratt


P. Royer

KU Leuven

B. Sibthorpe

Royal Observatory


0028-0836 (ISSN) 1476-4687 (eISSN)

Vol. 490 74-76


Astronomi, astrofysik och kosmologi