A peculiar class of debris disks from Herschel/DUNES - A steep fall off in the far infrared
Journal article, 2012
Context. The existence of debris disks around old main sequence stars is usually explained by continuous replenishment of small dust grains through collisions from a reservoir of larger objects. Aims. We present photometric data of debris disks around HIP 103389 (HD199260), HIP 107350 (HNPeg, HD206860), and HIP 114948 (HD219482), obtained in the context of our Herschel open time key program DUNES (DUst around NEarby Stars). Methods. We used Herschel/PACS to detect the thermal emission of the three debris disks with a 3 sigma sensitivity of a few mJy at 100 mu m and 160 mu m. In addition, we obtained Herschel/PACS photometric data at 70 mu m for HIP 103389. These observations are complemented by a large variety of optical to far-infrared photometric data. Two different approaches are applied to reduce the Herschel data to investigate the impact of data reduction on the photometry. We fit analytical models to the available spectral energy distribution (SED) data using the fitting method of simulated thermal annealing as well as a classical grid search method. Results. The SEDs of the three disks potentially exhibit an unusually steep decrease at wavelengths >= 70 mu m. We investigate the significance of the peculiar shape of these SEDs and the impact on models of the disks provided it is real. Using grain compositions that have been applied successfully for modeling of many other debris disks, our modeling reveals that such a steep decrease of the SEDs in the long wavelength regime is inconsistent with a power-law exponent of the grain size distribution -3.5 expected from a standard equilibrium collisional cascade. In contrast, a steep grain size distribution or, alternatively an upper grain size in the range of few tens of micrometers are implied. This suggests that a very distinct range of grain sizes would dominate the thermal emission of such disks. However, we demonstrate that the understanding of the data of faint sources obtained with Herschel is still incomplete and that the significance of our results depends on the version of the data reduction pipeline used. Conclusions. A new mechanism to produce the dust in the presented debris disks, deviations from the conditions required for a standard equilibrium collisional cascade (grain size exponent of -3.5), and/or significantly different dust properties would be necessary to explain the potentially steep SED shape of the three debris disks presented.
infrared: planetary systems
bolometric corrections
spitzer
main-sequence stars
circumstellar disk
nearby
effective
stars: individual: HIP 103389
solar neighborhood
circumstellar matter
geneva-copenhagen survey
stars: individual: HIP
stars
dust
temperatures
sun-like stars
Author
S. Ertel
Grenoble Alpes University
University of Kiel
S. Wolf
University of Kiel
J. P. Marshall
Universidad Autonoma de Madrid (UAM)
C. Eiroa
Universidad Autonoma de Madrid (UAM)
J. C. Augereau
Grenoble Alpes University
A. Krivov
Friedrich Schiller University Jena
T. Lohne
Friedrich Schiller University Jena
O. Absil
University of Liège
D. R. Ardila
California Institute of Technology (Caltech)
M. Arevalo
European Space Agency (ESA)
A. Bayo
European Space Observatory
G. Bryden
California Institute of Technology (Caltech)
C. del Burgo
UNINOVA-CA3
J. S. Greaves
University of St Andrews
G. Kennedy
University of Cambridge
J. Lebreton
Grenoble Alpes University
René Liseau
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
J. Maldonado
Universidad Autonoma de Madrid (UAM)
B. Montesinos
European Space Observatory
A. Mora
European Space Agency (ESA)
G.L. Pilbratt
European Space Agency (ESA)
J. Sanz-Forcada
European Space Observatory
K. R. Stapelfeldt
National Aeronautics and Space Administration (NASA)
G. J. White
Open University
STFC Rutherford Appleton Laboratory
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 541 A148Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201118077