A peculiar class of debris disks from Herschel/DUNES - A steep fall off in the far infrared
Artikel i vetenskaplig tidskrift, 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.

effective

main-sequence stars

circumstellar disk

bolometric corrections

circumstellar matter

infrared: planetary systems

stars: individual: HIP

sun-like stars

spitzer

temperatures

stars: individual: HIP 103389

stars

dust

nearby

solar neighborhood

geneva-copenhagen survey

Författare

S. Ertel

Verimag

Christian-Albrechts-Universität zu Kiel

S. Wolf

Christian-Albrechts-Universität zu Kiel

J. P. Marshall

Universidad Autonoma de Madrid (UAM)

C. Eiroa

Universidad Autonoma de Madrid (UAM)

J. C. Augereau

Verimag

A. Krivov

Friedrich-Schiller-Universität Jena

T. Lohne

Friedrich-Schiller-Universität Jena

O. Absil

Universite de Liège

D. R. Ardila

CalTech

M. Arevalo

European Space Astronomy Centre (ESA)

A. Bayo

European Space Observatory

G. Bryden

Jet Propulsion Laboratory, California Institute of Technology

C. del Burgo

UNINOVA-CA3

J. S. Greaves

University of St Andrews

G. Kennedy

University of Cambridge Institute of Astronomy

J. Lebreton

Verimag

René Liseau

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

J. Maldonado

Universidad Autonoma de Madrid (UAM)

B. Montesinos

European Space Observatory

A. Mora

European Space Astronomy Centre (ESA)

G.L. Pilbratt

ESTEC/SRE-SA

J. Sanz-Forcada

European Space Observatory

K. R. Stapelfeldt

NASA Goddard Space Flight Center

G. J. White

Open University

Rutherford Appleton Laboratory

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 541 A148

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201118077

Mer information

Senast uppdaterat

2018-04-13