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Ralf Siebenmorgen Köln 2012 ISM dust model Monte Carlo dust radiative transfer Proto-planetary disks: ring-like structures PAH destruction in proto-planetary.

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Presentation on theme: "Ralf Siebenmorgen Köln 2012 ISM dust model Monte Carlo dust radiative transfer Proto-planetary disks: ring-like structures PAH destruction in proto-planetary."— Presentation transcript:

1 Ralf Siebenmorgen Köln 2012 ISM dust model Monte Carlo dust radiative transfer Proto-planetary disks: ring-like structures PAH destruction in proto-planetary disks Ralf Siebenmorgen, Frank Heymann, Nikolai Voshchinikov, Endrik Krűgel Peter Scicluna (PhD) Shadows, gaps and ring-like structures in proto-planetary disks

2 Ralf Siebenmorgen Köln 2012 Si + aC : 60Å < a < µm ~ a -3.5 Graphite : 5Å < a < 80 Å ~ a -3.5 PAH : 30, 200 C ISM dust solar neighborhood Abundances [X/H in ppm]: 31Si + 150aC + 50gr + 30PAH

3 Ralf Siebenmorgen Köln 2012 PAH absorption cross section bump Malloci et al. (2007) Verstraete et al. 1992

4 Ralf Siebenmorgen Köln 2012 Siebenmorgen et al. (2001,2007) Nucleus of NGC1808 PAH emission cross section starbursts

5 Ralf Siebenmorgen Köln 2012 Linear polarisation Serkowski ~ Voshchinnikov (2012)

6 Ralf Siebenmorgen Köln 2012 Extinction: Prolate/ Sphere

7 Ralf Siebenmorgen Köln 2012 ISM dust Fitzpatrick (99)

8 Ralf Siebenmorgen Köln 2012 NGC2023 HD37903 Dust model : - Extinction - Emission - Polarisation 8μm Peeters et al. 2012

9 Ralf Siebenmorgen Köln 2012 Albedo Extinction

10 Ralf Siebenmorgen Köln 2012 Emission

11 Ralf Siebenmorgen Köln 2012 Polarisation

12 Ralf Siebenmorgen Köln 2012 Circular polarisation of dust: oblate versus prolate ~maximum of linear polarisation x ~Voshchinnikov (2002, 2012)

13 Ralf Siebenmorgen Köln 2012 ISM Krügel&Siebenmorgen (1994) Homogenous versus composite grains

14 Ralf Siebenmorgen Köln 2012 Arbitrary dust distribution Pseudo adaptive mesh 1.geometry 3D Monte Carlo Radiative Transfer

15 Ralf Siebenmorgen Köln geometry 2.source Source emits photon packages of equal energy Monte Carlo

16 Ralf Siebenmorgen Köln geometry 2. source 3. inter-action 4. dust temperature absorption / scattering / no interaction Monte Carlo = - ln( ζ)

17 Ralf Siebenmorgen Köln 2012 Photons escape model cloud Monte Carlo 1. geometry 2. source 3. inter-action 4. temperature 5. detection 6. Lightechos: time as 4 th dimension?

18 Ralf Siebenmorgen Köln 2012 Multiple photons at a time: vectorized MC 100 x faster Challenges: Cell locked when hit by photon Parallel random number generator (Mersene Twister) Graphical Processing Units (CUDA) Heymann & Siebenmorgen (2012)

19 Ralf Siebenmorgen Köln 2012 K06 : Krügel (2006) Dusty : Iveciz et al. (1999 ) Dust sphere: A V = 1000mag, heated by star Comparison of 2 ray tracing codes

20 Ralf Siebenmorgen Köln 2012 Sphere T * = 2500K ρ (r) = const. A V = mag ~5% for 0 MC versus benchmark Heymann & Siebenmorgen (2012)

21 Ralf Siebenmorgen Köln 2012 Method ParallelizationAdvantage Time Benchmark sphere τ~1000) Lucy YES (but floating) Optical thin>1h Bjorkman & Wood Partly (not independent) No iteration5min ourYESGPU<1min MC methods Heymann & Siebenmorgen (2012)

22 Ralf Siebenmorgen Köln D proto-planetary disk + spiral MHD (Fargo) density T * = 5800K L * = L sun A v =10mag 8au 3au

23 Ralf Siebenmorgen Köln 2012 ELT 42m PAH imaging

24 Ralf Siebenmorgen Köln 2012 D = 50pc 50mas at 11.3μm PSF dual band + coronograph ELT 42m PAH imaging

25 Ralf Siebenmorgen Köln 2012 D = 50pc 50mas at 11.3μm MIR imaging gap /px (μJy /px)

26 Ralf Siebenmorgen Köln 2012 Shadows in planet forming disks Gaps and ring-like structures:... are caused by hydrostatic + radiation balance without the need to postulate a companion/planet (Siebenmorgen & Heymann, 2012). PAH emission from disks: Low / high detection statistics of PAH in T Tauri / Herbig Ae stars is consistent with X-ray destruction of PAH (Siebenmorgen & Kr ű gel 2010).

27 Ralf Siebenmorgen Köln 2012 Armitage07 Lagrange et al, β Pic planet detection, Science10: …validates the use of disk structures as fingerprints of embedded planets. Gaps and ring-like structures in hydro-dynamical simulations

28 Ralf Siebenmorgen Köln 2012 Radiative transfer 1D slab geometry ?

29 Ralf Siebenmorgen Köln 2012 Puffed up inner rim Dullemond et al.2001 Kama et al Shadow T mid - lower

30 Ralf Siebenmorgen Köln 2012 Puffed up second rim T mid - warmer Shadow T mid - lower

31 Ralf Siebenmorgen Köln 2012 Puffed up third rim

32 Ralf Siebenmorgen Köln ) II) Hydrostatic and radiation balance I)T(x,y,z) by MC

33 Ralf Siebenmorgen Köln 2012 Proto-planetary disk models

34 Ralf Siebenmorgen Köln 2012 T Tauri disk

35 Ralf Siebenmorgen Köln 2012 Gaps and ring-like structures without planet extinction layer (photosphere) τ (z bot ) :=1

36 Ralf Siebenmorgen Köln 2012 Gaps and ring-like structures in the mid-IR emission

37 Ralf Siebenmorgen Köln 2012 Gaps and ring-like structures in scattered light

38 Ralf Siebenmorgen Köln 2012 PAH detection statistics PAH excitation / destruction PAH emission from disks

39 Ralf Siebenmorgen Köln 2012 PAH in a mono-energetic heating bath if | U f – U i – hν | < ½ ΔU f : A fi = K ν F ν / hν Siebenmorgen & Krűgel (2010) PAH emission from disks

40 Ralf Siebenmorgen Köln 2012 store PAH absorption events of each cell compute PAH emission neglect PAH self absorption Monte Carlo + PAH PAH emission from disks

41 Ralf Siebenmorgen Shadows in planet forming disks PAH emission from disks MC versus benchmark

42 Ralf Siebenmorgen Shadows in planet forming disks EoEo PAH destruction Unimolecular dissociation 1) single hard photon : independent of distance 2) many soft photons : ~AU Arrhenius form: t dis ~ exp(E o /kT) / ν 0 « t cool ~ 1s T min = E o /k ln(ν 0 ) ~2000K; E o ~ 5eV; ν 0 = Hz ΔE = 3N c kT min ~ 0.1 N c. E b => N c < 2 ΔE / [eV] PAH unstable Siebenmorgen & Kr ű gel (2010) T [K] time t cool t abs ~ 1h

43 Ralf Siebenmorgen Shadows in planet forming disks Stationary disk Sufficient X-ray photons? α τ = 1 z I } # C in PAH # hard γ absorption/sec PAH removal time << T Tauri pahse top extinction layer Σ = α/κ = h ν 4 π r 2 /Lκ

44 Ralf Siebenmorgen Shadows in planet forming disks Vertical mixing /v = t exp > t dis Disk lifetime => PAH replenishment Siebenmorgen & Krűgel (2010)

45 Ralf Siebenmorgen Shadows in planet forming disks PAH emission from disks T Tauri PAH emission from disks

46 Ralf Siebenmorgen Shadows in planet forming disks Mid-IR emission from Herbig disks Siebenmorgen & Heymann (2012)

47 Ralf Siebenmorgen Shadows in planet forming disks Shadows in planet forming disks Dust model for: extinction, emission, linear and circular polarisation Gaps and ring-like structures:... are caused by hydrostatic + radiation balance without the need to postulate a companion/planet (Siebenmorgen&Heymann, 2012). PAH emission from disks: Low / high detection statistics of PAH in T Tauri / Herbig Ae stars is consistent with X-ray destruction of PAH (Siebenmorgen & Kr ű gel 2010).

48 Ralf Siebenmorgen Köln 2012 PAH band ratios: ionisation dehydrogenation PAH emission from disks Galiano et al.08


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