1. D EBRIS DISKS WITH H ERSCHEL : AN OVERVIEW OF THE DUNES MODELING ACTIVITIES Jean-Charles Augereau, Steve Ertel, Alexander Krivov, Jérémy Lebreton, Torsten Löhne, Sebastian Müller, Philippe Thébault, Sebastian Wolf & the DUNES team: O. Absil, D. Ardila, M. Arévalo, A. Bayo, D. Barrado, C. Beichmann, G. Bryden, W. Danchi,C. del Burgo, C. Eiroa, D. Fedele, M. Fridlund, M. Fukagawa, B.M. González-Garcıa, E. Grün, R. Gutiérrez, A. M. Heras, I. Kamp, R. Launhardt, R. Liseau, R. Lorente, J. Maldonado, J. Marshall, R. Martínez-Arnaíz, G. Meeus, D. Montes, B. Montesinos, A. Mora, A. Morbidelli, H. Mutschke, T. Nakagawa, G. Olofsson, G. L. Pilbratt, I. Ribas, A. Roberge, J. Rodmann, J. Sanz-Forcada, E. Solano, K. Stapelfeldt, H. Walker, G. J. White

2. Debris disksDebris disks K ALAS et al. 2008 Another expression for planetary systems Towards getting a complete picture of planetary systems

3. DUNES projectDUNES project Our own solar system is a debris disk (M. Wyatts talk). Kuiper Belt (A. Krivovs talk) Low luminosity extra-solar Kuiper Belt remained elusive to previous space missions (A. Moro-Martins talk) Two Herschel Open Time Key projects : DEBRIS (B. Matthewss talk) DUNES (C. Eiroas talk) + GTO programs (B. Vandenbussches talk) This talk : No statistics Imaging capabilities of Herschel and how it breaks degeneracy between models Overview of the modeling approaches in the DUNES team

4. The q 1 Eri planetary systemThe q 1 Eri planetary system pre-Herschel understanding A J UPITER - MASS PLANET M sin i: 0.93 M Jupiter Semi-major axis: 2.03 AU Eccentricity : 0.1 M AYOR et al. 2003, B UTLER et al. 2006 A K UIPER - LIKE BELT IRAS, ISO and Spitzer: cold dust, with a luminosity a few 100 times that of the Kuiper Belt (L disk /L star ~4x10 -4 ) Sub-mm APEX/LABOCA images: disk extent is up to several tens of arcsec ( L ISEAU et al. 2008 ) T HE S TAR Spectral type: F8 Distance : 17.4 pc Age : ~ 2 Gyr

5. Pre-Herschel photometry of q 1 Eri

6. Post-Herschel photometry of q 1 Eri SED fitting : known degeneracy between dust properties and disk structure

7. SED fitting: degeneracy between dust properties and disk structure Simplest debris disk model : Ring – like geometry (Kuiper Belt, Fomalhaut, HR4796, and many others): 1 main parameter = the peak density position (r peak ) Donhanyi grain size distribution : 1 main parameter = minimum grain size (s min ) Silicate grains

8. SED fitting: degeneracy between dust properties and disk structure HST images suggest a peak at 83AU (4.8, S TAPELFELDT et al., in prep. )

9. PACS observations of q 1 EriPACS observations of q 1 Eri Disk spatially resolved at all PACS wavelengths Disk marginally resolved along the minor axis: inclination > 55 deg See A&A Letter by L ISEAU et al. 2010

10. PACS image fittingPACS image fitting

11. Breaking the degeneracyBreaking the degeneracy Detailed simultaneous modeling of the SED and PACS images required to unveil the disk structure, dust properties and dynamical history

12. The basic DUNES modeling suiteThe basic DUNES modeling suite Classical : Radiative transfer, assuming analytic functions for the surface density and size distribution Two radiative transfer codes, with different fitting strategies: GR A T ER (G RENOBLE ) : bayesian statistical analysis SA N D (K IEL ) : simulated annealing minimization scheme Collisional : Radiative transfer, fed by results from collisional code ACE that generates and evolves the disk from the sources ACE, SEDUCE and SUBITO codes (J ENA ) Two modeling approaches, Three fitting strategies, Five codes

13. Advantages & limitations of the codesAdvantages & limitations of the codes GR A T ER [Grenoble, J.-C. A UGEREAU & J. L EBRETON ] Fast exploration of large parameter spaces Stored grid for subsequent statistical analysis (24 million models for q 1 Eri) Post-processing easy (e.g. re-computation of 2 with different weights) Simplistic description of the disk properties & no direct link to parent bodies SA N D [Kiel, S. E RTEL & S. W OLF ] Fast: finds fit among ~10 11 models in ~70 hours Large number of free parameters possible Limited initial constraints on disk physics Simplistic description of the disk properties & no direct link to parent bodies ACE + SEDUCE + SUBITO [Jena, A. K RIVOV, T. L ÖHNE, S. M ÜLLER ] Deep physical modeling of the disk from the sources Realistic description of disk properties Mass and dynamical excitation of unseen parent bodies CPU-demanding : 20 models in 3 months

14. Classical approach: statistical (bayesian) analysis 40-50% of ice Surface density goes as r -2 Size distribution: -3.5 power index Minimum grain size: ~ 1 to 2 µm Belt position ~ 75 AU Inclination ~ 71 o

15. Classical Approach (GRaTer & SAnD codes) Best fit ( r 2 = 1.5, dof=100) : D UST DISK : Mass : 0.04 M Earth Surface density: r -2 Belt peak position: 75-80AU Fit to the SED Fit to the PACS Radial Profiles G RAIN PROPERTIES : Close to 50-50 silicate-ice mixture Minimum grain size ~ 1.5 m Size distribution: -3.5 power law index

16. Best fit: D UST DISK & GRAIN PROPERTIES : Mass : 0.02 M earth 50-50 silicate-ice mixture Coupled radial-size distribution Collisional Approach (ACE+SUBITO+SEDUCE codes) P ARENT BELT : Location: 75-125 AU Eccentricities: 0.0…0.1 Mass : ~1000 M earth (if 2 Gyr), but ~ 100 M earth (if 0.5Gyr) Delayed stirring ? See poster by S. Müller

17. Summary of model results Consistent results between the three codes: Dust mass Grain size distribution Dust composition (ice likely) Parent belt position at ~ 75AU Dust surface density consistent with a collisionally active debris disk Open questions: Lacking inner (<5) 70 m emission Our unconvolved view of the q 1 Eri Kuiper Belt at PACS wavelengths

18. Deconvolved imagesDeconvolved images Deconvolution with the MCS algorithm (Magain, Courbin & Sohy 1998, ApJ 494, 472) Two blobs, suggestive of an inclined ring Possible asymmetry between the two sides 70 µm100 µm

19. The HD 207129 planetary systemThe HD 207129 planetary system pre-Herschel understanding A K UIPER - LIKE BELT IRAS, ISO, Spitzer APEX/LABOCA: cold dust, with a fractional IR luminosity L disk /L star of ~1.4x10 -4 ( J OURDAIN ET AL. 1999, N ILSSON ET AL. 2010, K RIST ET AL. 2010 ) T HE S TAR Spectral type: G2 Distance : 15.6 pc Age : ~ 5 Gyr

20. PACS images Disk resolved at all PACS wavelengths Inclined, ring-like disk Poster by L ÖHNE ET AL.

21. Deconvolved PACS images Brightness peak at around 130-140 AU One of the most extended debris ring Faint brightness asymmetry between the two ansae

22. Collisional Approach: preliminary results Steady-state dust production from a 85 M earth planetesimal belt at 120 – 160 AU, and dust mass of 6 x 10 -3 M earth Lack of emission in the inner regions

23. Conclusions O BSERVATIONS Images of extra-solar Kuiper belts with unprecedented resolution and sensitivity Inner gaps seen in thermal emission at < 100 m for the first time The belts show some degree of asymmetry M ODELS : Degeneracy between dust properties and disk structure broken thanks to the PACS images Probing dust composition Probing collisional history: support to delayed stirring in the case of q1 Eri (self-stirring by Plutos, or stirring by q 1 Eri c, or even by q 1 Eri b) DUNES modeling toolbox works fine, we are ready for more data More about q 1 Eri: poster by M ÜLLER More about HD 207129 : poster by L ÖHNE More about OTKP DUNES: talk by E IROA More about Cold Debris Disks : talk by A. K RIVOV

24. Additional slidesAdditional slides

25. Coll approach: dust distributionsColl approach: dust distributions