Modeling interactions between a debris disc and planet: which initial conditions?

Transcription

1 Modeling interactions between a debris disc and planet: which initial conditions? Elodie Supervisors : Prof Sarah Maddison (Swinburne) Prof Jarrod Hurley (Swinburne) Crédit : NASA/JPL-Caltech

2 outline I. Background about debris discs II. Aims of my project III. About initial conditions in simulations IV. Conclusions and questions

3 outline I. Background about debris discs

4 Story : from molecular cloud to a debris disc Protoplanetary disc Gravitational collapse Molecular clouds Condensation Photoevaporation Radial migration T ~ few Myrs Photoevaporation T > 10 Myrs Debris disc ex : Kuiper Belt (Booth et al. 2009) Transition disc

5 Story : from molecular cloud to a debris disc Protoplanetary disc Gas rich Optically thick Size 1000 AU Grain growth Molecular clouds Gas poor Optically thin Size 100 AU Grain fragmentation Debris disc ex : Kuiper Belt (Booth et al. 2009) Transition disc

6 The birth ring Theory 500 m

7 The birth ring Theory

8 The birth ring Theory µm cm Collisional cascade

9 The birth ring Theory µ m cm 500 m

10 The birth ring Theory µ m cm 500 m

11 Observations of debris discs with planets companions : Wyatt (2006)

12 3 ways how planets can perturbed debris discs : ø resonance interaction (Quillen & Thorndike, 2002), (Ozernoy et al., 2000) ø secular perturbations by eccentric/inclined planets (Wyatt et al., 1999) ø dust scattering Effects of resonance : cause dust migration toward resonance location with planets depends on planet mass and eccentricity (Kuchner & Holman 2003)

13 3 ways how planets can perturbed debris discs : ø resonance interaction (Quillen & Thorndike, 2002), (Ozernoy et al., 2000) ø secular perturbations by eccentric/inclined planets (Wyatt et al., 1999) ø dust scattering Secular perturbations : An inclined/eccentric planet inclined/eccentric debris disc

14 outline I. Background about debris discs II. Aims of my project

15 Question : Detection of perturbed disc new tool for exoplanets hunting? Goal of my PhD : efficiently probe the presence of hidden planets inside debris discs with a toolbox. Method: compare simulations with observations to infer or exclude presence of planets inside the disc

16 Numerical modeling of debris discs 1) Planet-Disc interaction is dynamically modeled by N-Body simulations : Input: Initial conditions (location, mass) Ouput: Orbit evolution at any t _ N-body (grains + planets) SWIFT (Levison & Duncan, 1994) _ include radiation forces for smaller grains implemented by myself 2) Disc emission is modeled by radiative transfer: Input: Dust density distribution, dust properties Output: SEDs, synthetic images at any _ Monte Carlo and ray tracing code MCFOST (Pinte et al. 2006)

17 Modeling HD and HD Rodigas et al predictions : first theoritical formula linking a debris disc width in scattered light to planetary parameters : location, mass. HD , Krist et al. (2012) HD , Krist et al. (2010) Aim of the project : testing the Rodigas predictions with numerical simulations on the HD and HD system see if the predicted planetary parameters can reproduce the discs' features.

18 Method used to test the predictions

19 Results for HD with Rodigas et al. Planetary parameters: <13 HD : HST observation and best fit model < Brightness profile with sharp inner edge GOOD MATCH!

20 Results for HD with Rodigas et al. Planetary parameters: 28 HD : HST observation and best fit model Brightness profile with sharp inner edge Relatively GOOD MATCH!

21 outline I. Background about debris discs II. Aims of my project III. About initial conditions in simulations

22 What about initial conditions in debris disc simulations? Initial conditions to choose: thin or broad parent body belt? Disc eccentricity? Planet-disc alignment? In the literature? Various initial conditions used with few or no justifications.

23 Class I: dynamical cold disc IC: 0<e<0.04, no planet-disc alignment. Class III: dynamical warm disc IC: 0<e<0.3, no planet-disc alignment Class IIa: forced thin disc IC: e~eforced by secular interaction with the planet, planet-disc are apse aligned. Class IIb: forced broad disc IC: e~ 0, planet-disc are apse aligned 0 < e < 2eforced

24 Class I: dynamical cold disc IC: 0<e<0.04, no planet-disc alignment. Origin: low mass planet with e damped by protoplanetary disc, e excited by later process (scattering?) Class III: dynamical warm disc IC: 0<e<0.3, no planet-disc alignment Origin: massive planet opened a gap in protoplanetary disc, e planet excited e disc excited by Lindblad resonance. Class IIa: forced thin disc IC: e~eforced by secular interaction with the planet, planet-disc are apse aligned. Origin: After e planet excited, in a disc with high collisional activity free eccentricity are damped and only the forced component remains, planetesimals aligned with the planet. Class IIb: forced broad disc IC: e~ 0, planet-disc are apse aligned 0 < e < 2eforced

25 Class I: dynamical cold disc IC: 0<e<0.04, no planet-disc alignment. Origin: low mass planet with e damped by protoplanetary disc, e excited by later process (scattering?) Class III: dynamical warm disc IC: 0<e<0.3, no planet-disc alignment Origin: massive planet opened a gap in protoplanetary disc, e planet excited e disc excited by Lindblad resonance. Class IIa: forced thin disc IC: e~eforced by secular interaction with the planet, planet-disc are apse aligned. Origin: After e planet excited, in a disc with high collisional activity free eccentricity are damped and only the forced component remains, planetesimals aligned with the planet. Class IIb: forced broad disc IC: e~ 0, planet-disc are apse aligned 0 < e < 2eforced Do the initial conditions have an impact on the final disc?

26 Impact of initial conditions in simulations of debris discs? Run a set of 12 simulations covering initial conditions from Class I, Class IIa, Class IIb and Class III: see if/how does the resulting disc structure change? Simulation: Disc + a 2 Jupiter mass planet comparison of disc final offset, at 30 AU with ep =0.3 width, peak location, as well as secular and resonance evolution.

27 Disc aligned with the planet within 1 tsec Disc gets broader around 0.5 tsec Class I, IIb and III + broad parent body belt very broad disc

28 Disc aligned with the planet within 1 tsec Disc gets broader around 0.5 tsec Disc eccentricity range is wide: due to secular forcing + free component. Final disc structure: offset= 15 AU Peak = 50 AU } e disc = 0.3 Disc width = Class I, IIb and III + broad parent body belt very broad disc

29 Disc aligned with the planet within 1 tsec Disc gets broader around 0.5 tsec Class I, IIb and III + thin parent body belt broad disc

30 Disc aligned with the planet within 1 tsec Disc gets broader around 0.5 tsec Disc eccentricity range is wide: due to secular forcing + free component. Final disc structure: offset= 12 AU Peak = 48 AU } e disc = 0.25 Disc width = 0.3 Class I, IIb and III + thin parent body belt broad disc

31 Broad parent belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 14 AU Peak = 48 AU } edisc = 0.29 Disc width = 0.3 Thin parent body belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 8 AU Peak = 60 AU } e disc = 0.14 Disc width = 0.09 Class II a: disc is narrow, dominated by single event

32 Broad parent belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 14 AU Peak = 48 AU } edisc = 0.29 Disc width = 0.3 Thin parent body belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 8 AU Peak = 60 AU } e disc = 0.14 Disc width = 0.09 Class II a: disc is narrow, dominated by single event

33 Broad parent belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 14 AU Peak = 48 AU } edisc = 0.29 Disc width = 0.3 Thin parent body belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 8 AU Peak = 60 AU } e disc = 0.14 Disc width = 0.09 Class II a: disc is narrow, dominated by single event

34 Broad parent belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 14 AU Peak = 48 AU } edisc = 0.29 Disc width = 0.3 Thin parent body belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 8 AU Peak = 60 AU } e disc = 0.14 Disc width = 0.09 Class II a: disc is narrow, dominated by single event

35 Broad parent belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 14 AU Peak = 48 AU } edisc = 0.29 Disc width = 0.3 Thin parent body belt Disc SB profile is narrower Strong 3:1 MMR Final disc structure: offset= 8 AU Peak = 60 AU } e disc = 0.14 Disc width = 0.09 Class II a: disc is narrow, dominated by single event

36 SUMMARY: Class II a Class I, II b & III

37 Conclusions Interaction between a planet and a debris disc leaves observational signatures (gap, offset, warp...) We can trace back the presence of hidden planet by studying the debris disc asymmetries use a modified N-Body integrator to model the dynamic and a radiative transfer code to model the emission and compare with observations. What about initial conditions? _ several Classes of IC, depending of the past of the systems _ Class I, II b and III (dynamically cold & warm) gives same results _ Class II a: the forced disc, where the disc initial eccentricity and apse alignment with the planet is forced give a narrower disc.

38 Questions If Class I (dynamically cold disc resulting from low mass planet in PP disc) is equivalent to Class III (dynamically warm disc resulting from gap opening by a massive planet) The capacity of a planet to open a gap or not does not influence its debris disc phase? If Class II a (secular forced parent body belt) gives a narrower structure than other classes Discs with eccentric planet and high collision rates enough to damp the free eccentricities can only be narrow structure? Thank you!