Ertel, S. and Wolf, S. and Marshall, J. P. and Eiroa, C. and Augereau, J.-C. and Krivov, A. V. and Löhne, T. and Absil, O. and Ardila, D. and Arévalo, M. and Bayo, A. and Bryden, G. and del Burgo, C. and Greaves, J. and Kennedy, G. and Lebreton, J. and Liseau, R. and Maldonado, J. and Montesinos, B. and Mora, A. and Pilbratt, G. L. and Sanz-Forcada, J. and Stapelfeldt, K. and White, G. J. (2012) A peculiar class of debris disks from Herschel/DUNES - A steep fall off in the far infrared. Astronomy and Astrophysics, 541 . Art. No. A148. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20120625-151524849
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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 3σ sensitivity of a few mJy at 100 μm and 160 μm. In addition, we obtained Herschel/PACS photometric data at 70 μm 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 μm. 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.
|Additional Information:||© 2012 ESO. Received 12 September 2011; Accepted 19 March 2012; Published online 22 May 2012. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. We thank Kate Su for the re-reduction of the Spitzer/MIPS photometry used in this work. Furthermore, we thank the whole DUNES team for valuable discussion. S. Ertel thanks for financial support from DFG under contract WO857/7-1 and for general support from K. Ertel. C. Eiroa, J. Maldonado, J. P. Marshall, and B. Montesinos are partially supported by Spanish grant AYA 2008/01727. J.-C. Augereau and J. Lebreton thank financial support through PNP-CNES. A. V. Krivov ans T. Löhne thank for financial support from DFG under contracts KR2164/9-1 and LO1715/1-1. O. Absil is supported by an F.R.S.-FNRS Postdoctoral Fellowship. S. Ertel, J.-C. Augereau and J. Lebreton thank the French National Research Agency (ANR) for financial support through contract ANR-2010 BLAN-0505-01 (EXOZODI). This work was partly funded by the Fundação para a Ciência e a Tecnologia (FCT) through the project PEst-OE/EEI/UI0066/2011.|
|Subject Keywords:||circumstellar matter; stars: individual: HIP 103389; infrared: planetary systems; stars: individual: HIP 107350; infrared: stars; stars: individual: HIP 114948|
|Official Citation:||A peculiar class of debris disks from Herschel/DUNES - A steep fall off in the far infrared S. Ertel, S. Wolf, J. P. Marshall, C. Eiroa, J.-C. Augereau, A. V. Krivov, T. Löhne, O. Absil, D. Ardila, M. Arévalo, A. Bayo, G. Bryden, C. del Burgo, J. Greaves, G. Kennedy, J. Lebreton, R. Liseau, J. Maldonado, B. Montesinos, A. Mora, G. L. Pilbratt, J. Sanz-Forcada, K. Stapelfeldt and G. J. White A&A 541 A148 (2012) DOI: http://dx.doi.org/10.1051/0004-6361/201118077|
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|Deposited By:||Aucoeur Ngo|
|Deposited On:||25 Jun 2012 23:11|
|Last Modified:||26 Dec 2012 15:23|
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