Volume 518, July-August 2010Herschel: the first science highlights
|Number of page(s)||15|
|Section||Planets and planetary systems|
|Published online||31 August 2010|
Kuiper belts around nearby stars*
Department of Astronomy, Stockholm University, AlbaNova University Center, Roslagstullsbacken 21, 106 91 Stockholm, Sweden e-mail: [ricky;alexis;olofsson]@astro.su.se
2 Onsala Space Observatory, Chalmers University of Technology, SE-439 92 Onsala, Sweden e-mail: [rene.liseau;per.bergman]@chalmers.se
3 ESA Astrophysics Missions Division, ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands e-mail: firstname.lastname@example.org; email@example.com
4 SRON, Postbus 800, 9700 AV Groningen, The Netherlands e-mail: firstname.lastname@example.org
5 ESA/ESTEC Space Environment and Effects Section, PO Box 299, 2200 AG Noordwijk, The Netherlands e-mail: email@example.com
6 Université Joseph Fourier/CNRS, Laboratoire d'Astrophysique de Grenoble, UMR 5571, Grenoble, France e-mail: firstname.lastname@example.org
7 Dpto. Física Teórica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain e-mail: email@example.com
8 Observatoire de Paris, Section de Meudon, 92195 Meudon Principal Cedex, France e-mail: firstname.lastname@example.org
9 Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA, UK e-mail: email@example.com
10 Science and Technology Facilities Council, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
Accepted: 18 May 2010
Context. The existence of dusty debris disks around a large fraction of solar type main-sequence stars, inferred from excess far-IR and submillimetre emission compared to that expected from stellar photospheres, suggests that leftover planetesimal belts analogous to the asteroid- and comet reservoirs of the solar system are common.
Aims. Sensitive submillimetre observations are essential to detect and characterise cold extended dust originating from collisions of small bodies in disks, belts, or rings at Kuiper-belt distances (30–50 AU or beyond). Measurements of the flux densities at these wavelengths will extend existing IR photometry and permit more detailed modelling of the Rayleigh-Jeans tail of the disks spectral energy distribution (SED), effectively constraining dust properties and disk extensions. By observing stars spanning from a few up to several hundred Myr, the evolution of debris disks during crucial phases of planet formation can be studied.
Methods. We observed 22 exo-Kuiper-belt candidates at 870 μm, as part of a large programme with the LABOCA bolometer at the APEX telescope. Dust masses (or upper limits) were calculated from integrated 870 μm fluxes, and fits to the SED of detected sources revealed the fractional dust luminosities , dust temperatures , and power-law exponents β of the opacity law.
Results. A total of 10 detections with at least 3σ significance were made, out of which five (HD 95086, HD 131835, HD 161868, HD 170773, and HD 207129) have previously never been detected at submillimetre wavelengths. Three additional sources are marginally detected with > 2.5σ significance. The best-fit β parameters all lie between 0.1 and 0.8, in agreement with previous results indicating the presence of significantly larger grains than those in the ISM. From our relatively small sample we estimate , with α ~ 0.8–2.0, and identify an evolution of the characteristic radial dust distance that is consistent with the increase predicted from models of self-stirred collisions in debris disks.
Key words: circumstellar matter / planetary systems / planets and satellites: formation / Kuiper belt: general / submillimeter: planetary systems
© ESO, 2010
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