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1. Debris disks with Herschel:an overview of the DUNES modeling activities

   Jean-Charles Augereau, Steve Ertel, Alexander Krivov, Jérémy Lebreton, Torsten Löhne, Sebastian Müller, Philippe Thébault, SebastianWolf & the DUNES team:O. Absil, D. Ardila, M. Arévalo, A. Bayo, D. Barrado, C. Beichmann, G. Bryden, W. Danchi,C. delBurgo, 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 disks Another expression for planetary systems Kalas et al. 2008 Towards getting a complete picture of planetary systems
3. DUNES project Our own solar system is a debris disk (M. Wyatt’s talk).Kuiper Belt (A. Krivov’s talk) Low luminosity extra-solar Kuiper Belt remained elusiveto previous space missions (A. Moro-Martin’s talk) Two Herschel Open Time Key projects : DEBRIS (B. Matthews’s talk) DUNES (C. Eiroa’s talk) + GTO programs (B. Vandenbussche’s talk) This talk : No statistics Imaging capabilities of Herschel and howit breaks degeneracy between models Overview of the modeling approaches in the DUNES team
4. The q1Eri planetary systempre-Herschel understanding The Star Spectral type: F8 Distance : 17.4 pc Age : ~ 2 Gyr A Jupiter-mass planet A Kuiper-like belt IRAS, ISO and Spitzer: cold dust, with a luminosity a few 100 times that of the Kuiper Belt(Ldisk/Lstar ~4x10-4) Sub-mm APEX/LABOCA images: disk extent is up to several tens of arcsec (Liseau et al. 2008) M sin i: 0.93 MJupiter Semi-major axis: 2.03 AU Eccentricity : 0.1 Mayor et al. 2003, Butler et al. 2006
5. Pre-Herschel photometryof q1Eri
6. Post-Herschel photometryof q1Eri 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 (rpeak) Donhanyi grain size distribution :1 main parameter = minimum grain size (smin) Silicate grains
8. SED fitting: degeneracy between dust properties and disk structure HST images suggest a peak at 83AU (4.8”, Stapelfeldt et al., in prep.)
9. PACS observations of q1Eri See A&A Letter by Liseau et al. 2010 Disk spatially resolved at all PACS wavelengths Disk marginally resolved along the minor axis: inclination > 55 deg
10. PACS image fitting
11. Breaking 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 suite Two modeling approaches, Three fitting strategies, Five codes Classical: Radiative transfer, assuming analytic functions for the surface density and size distribution Two radiative transfer codes, with different fitting strategies: GRaTer (Grenoble) : bayesian statistical analysis SAnD (Kiel) : 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 (Jena)
13. Advantages & limitations of the codes GRaTer[Grenoble, J.-C. Augereau & J.Lebreton] Fastexploration of large parameter spaces Stored grid for subsequent statistical analysis (24 million models for q1Eri) Post-processing easy(e.g. re-computation of c2 with different weights) Simplistic description of the disk properties & no direct link to parent bodies SAnD[Kiel, S. Ertel & S. Wolf] Fast: finds fit among ~1011 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. Krivov, T. Löhne, S. Müller] 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 ~ 71o
15. Classical Approach (GRaTer & SAnD codes) Grain properties: Close to 50-50 silicate-ice mixture Minimum grain size ~ 1.5 mm Size distribution: -3.5 power law index Fit to the SED Fit to the PACS Radial Profiles Best fit (cr2 = 1.5, dof=100): Dust disk : Mass : 0.04 MEarth Surface density: r-2 Belt peak position: 75-80AU
16. Collisional Approach (ACE+SUBITO+SEDUCE codes) See poster by S. Müller Parent belt: Location: 75-125 AU Eccentricities: 0.0…0.1 Mass :~1000 Mearth(if 2 Gyr),but ~ 100 Mearth(if 0.5Gyr) Delayed stirring ? Best fit: Dust disk & grain properties: Mass : 0.02 Mearth 50-50 silicate-ice mixture Coupled radial-size distribution
17. Summary of model results Our unconvolved view of the q1Eri Kuiper Beltat PACS wavelengths Consistent results between the three codes: Dust mass Grain size distribution Dust composition (ice likely) Parent belt position at ~ 75AU Dust surface density consistentwith a collisionally active debris disk Open questions: Lacking inner (<5”) 70mm emission
18. Deconvolved images 70 µm 100 µm 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
19. The HD 207129 planetary systempre-Herschel understanding The Star Spectral type: G2 Distance : 15.6 pc Age : ~ 5 Gyr A Kuiper-like belt IRAS, ISO, Spitzer APEX/LABOCA: cold dust, with a fractional IR luminosity Ldisk/Lstar of ~1.4x10-4(Jourdain et al. 1999, Nilsson et al. 2010, Krist et al. 2010)
20. PACS images Disk resolved at all PACS wavelengths Inclined, ring-like disk Poster by Löhne 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 Mearthplanetesimal belt at 120 – 160 AU, and dust massof 6 x 10-3Mearth Lack of emission in the inner regions
23. Conclusions More about q1Eri:poster byMüller More about HD 207129 : poster by Löhne More about OTKP DUNES: talk by Eiroa More about Cold Debris Disks : talk by A. Krivov Observations Images of extra-solar Kuiper belts with unprecedented resolutionand sensitivity Inner gaps seen in thermal emission at <100mm for the first time The belts show some degree of asymmetry Models: 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 q1Eri c, or even by q1Eri b) DUNES modeling “toolbox” works fine, we are ready for more data
24. Additional slides
25. Coll approach: dust distributions