Non-symetrical Protoplanetary Disks

1
Non-symetrical Protoplanetary Disks

• Annibal Hetem Jr. (FAFIL/FSA)annibal_at_fsa.br
• Jane Gregorio-Hetem (IAG/USP)jane_at_astro.iag.usp.
  br

2
Protoplanetary disks

• Protoplanetary disks are thought to be the
  progenitors of planetary systems.
• Gravitational interactions may cause the dust and
  gas in the disk to condense into planetesimals.
• This process competes against the stellar wind,
  which drives the gas out of the system, and
  accretion, which pulls material into the central
  star.

3
(No Transcript)
4
(No Transcript)
5
Protoplanetary disk classification

• We chose disk models based on an evolutionary
  scenario for the HAeBe stars, proposed by Malfait
  et al. (1998), similar to what is seem in TT
  stars.
• We chose three main scenarios
• Single dust disk with near-IR and far-IR excess.
• Single dust disk with far-IR excess.
• Double disk (a disk with a radial gap)

6
HAeBe Evolutive Sequence(Malfait et al. 1998)
7
Examples of HAeBe candidates classified as group
(1) PDS 027 (2) (a) PDS 126 (b) PDS0318 and
(3) PDS 545. (Sartori, Gregorio-Hetem Hetem
2003 BAS Meeting)
8
Periodic Eclipses

• Light curves of AA Tau
• (Bouvier et al. 1999, Ménard et al 2003, Alencar
  et al. 2004 1st Brasil CoRoT Workshop)

9
Flared disk model
10
Model Geometry(Chiang Goldreich 1997)
Grazingangle
Internalheight
Externalheight
Hole radius
Disk radius
11
The model formalism
12
The model formalism
13
Light curves

• CoRoT data shall be plenty of star occultation
  details.

14
Light curve simulationneeded

• Very difficult to achieve due to disk model
  complexity.
• Slow code due to integrations.
• Program is sensitive to tilt and rotation angles.

15
3D computer graphics

• Used as image sequence generator.
• Builds very realistic scenes, with perspective
  and overlapping.
• Accepts all physical light parameters.
• Need few parameters.
• Fast.

16
Technique
Modelchoice
17
Planet Transit

• High albedo

18
Planet Transit

• Low albedo

19
Flared disk

• HAeBe

Model 1
20
Flared disk

• T Tauri

Model 1
21
Flared disk

• Binary

Model 1
22
Flared disk

• Large inner hole

Model 2
23
Flared disk

• Radial gap

Model 3
24
Protoplanetary gap

• The presence of a gap is indicative of
  protoplanetary activity.

God! A protoplanet!
25
TheoryLindblad Resonances

• Occurs when the natural epicyclic frequency of
  the disk is an exact multiple of the forcing
  frequency.
• This interaction has the effect of pushing
  material away from the resonance point, and is
  opposed by viscous torques.

Nelson et al 2000
26
TheoryThe gap

• If tidal torques dominate, a large annular gap in
  the disk opens up around the point, and the disk
  becomes highly non-linear at that location.

Masset Snellgrove 2001
27
Gap Tidal forces protoplanet

• See
• Nelson et al 2000Masset Snellgrove
  2001Papaloizou et al. 2000
• http//www.maths.qmul.ac.uk/mds
• http//www-star.qmw.ac.uk/masset/intertmr.html

28
Presence of a radial gap

• (or The presence of a missing ring)

• A gap in disk generates slightily differences in
  the light curve (when compared to stardisk
  case).
• CoRoT sensitivity can detect missing rings due to
  proto-planets.
• The detection need to be confirmed by modeling
  techniques.

29
Modeling techniques

• CoRoT data parameter fitting!

30
Too many parameters

• From disk model itselfradii (hole, disk)
  grazing angle law height (internalexternal)
  density law temperature law.
• From tilt and rotation geometry.
• Gap geometry.

31
SolutionGenetic Algorithm fitting

• Admits large number of parameters.
• Complexity model independent.
• Robust.
• Formal.(for an exemple see discussion in Fiege
  et al. 2004)

32
Implementation
Avaliator(model)
Generator
Solutionsset
Judge
Statistics
Executor
33
Non-symetrical Protoplanetary Disks

• Thank You!

• annibal_at_fsa.br