Transcript Poster session 1 Tuesday 18 August 11:30 Rapid Variation of Spectral Energy Distribution in Protostellar Disks Te Ke1,2, Hao Huang1,2, and D.N.C.

Poster session 1
Tuesday 18 August 11:30
Rapid Variation of Spectral Energy Distribution in Protostellar
Disks
Te Ke1,2, Hao Huang1,2, and D.N.C. Lin2,3
1School
of Physics, Peking University, Beijing China, 2Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing China, 3Department of
Astronomy and Astrophysics, University of California, Santa Cruz, CA, USA
Quasi-equilibrium solution:
Abstract
Number density of electrons in the
Observations of T Tauri stars reveal the rapid significant variation of spectral
frontier area of inner rim
energy distribution in protostellar disks with time scale as short as one week.
ne  ne 0
Spectral energy distribution in protostellar disks is determined by the disks'
internal dissipation and reprocessing of irradiation from their host stars. We
show that the observed rapid X-ray flares from T Tauri stars can significantly
modulate the ionization fraction of the gas and charges carried by the grains near
the surface of
their host stars,
with
e 
md
 130days
Z  ve e
adjust their distances from the midplane.
Consequently, the shadow casted by
the grains on the surface of the inner disk regions attenuates in the flux of stellar
photons irradiated at several AU's from the central stars.
We use this model to
Grains’ Equation of Motion
md v 
Charge on one grain
the inner regions of their surrounding disks. In the proximity of
the newly charged grains are accelerated by the stellar field and
t
e
E0
4 0 (
) rd
e
Q0
Relaxation
time
of
charge
on
md
GM *r
 Q0 v  B   vv
r3
the
grain
Q
104 s
 e , (t
10days)
account for the variabilities of spectral energy distribution, at a few micron range,
on time scales of a few days.
Spectrum Variation
Structure of Disk
As the inner rim changed its shape, the boundary of the shadowed region laid
We consider a slight flaring multi-layered protostellar disk with the inner optical
much closer to the central star. The time scale of this process is several days.
In the Figure below, we can see that the compression of the rim lower the
truncation due to the sublimation of grains (Dullemond et al.)
spectral intensity at 8 micron, while the intensity at 20 micron rise as larger area
Optical height of the disk
T 12 R 12
H  (
) (
) R
T0
R*
(
8
 s 17 T* 74 R 72
2 1
)7  7 (
) (
) (
) R
7
2 i
T0
R*
H rim   rim (
Drim 
Tevp
T0
1
)2 (
Rrim 1
) 2 Rrim
R*
of the disk is exposed to the central star.
2 h( Rrim )
1
2
exp(
 rim
)
 v ( Rrim )
2
Outer border of the shadow region
Optical height and thickness of the inner
rim
R fl  (
 s  12 T* 2 H rim 72
2 1
) 2  4 (
) (
) (
) R*
7
2 i
T0
Rrim
Gas Ionization And Motion of Charging Grains
Equation set of ionization and charging process
dQ
 e(ve e  v p p ) ne
dt
dne
LX

Z

 X ( EX ) 
ve e (Q ) ne
2
dt
4 Rrim
E0 m p
md
Conclusions And Future Work
We scrutinize the process of gas ionization due to stellar X-ray flaring and
numerically analyze the motion of charged grains.
We explain the rapid variation of spectral energy distribution in protostellar
disks by presenting the time sequence chart of disk SED variation, which
generally matches observations.
Using our model, it may be possible to determine the disks' thickness as a
function of
their radius from the high-cadence SED observation, analogous
to the technique of reverberation mapping.
Reference
Dullemond,C.P., Dominik,C. & Natta,A., 2001, ApJ, 560, 975D
A new switch for artificial viscosity in SPH disk simulations
The Hall Effect in Star Formation
C. Braiding, M. Wardle
• Modelling star and disc formation with ambipolar and Hall
diffusion.
• Axisymmetric, vertically averaged collapsing disc (, V, B, H
depend on r & t). Self-similar (depend only on x ~ r/t).
• Numerically solve the ODEs (shocks, critical points).
• Global orientation of the field changes the dynamics (more
shocks, critical points).
Poster #4
Pre-Transitional Disks:
The Missing Link for Planet Formation in Disks
Catherine Espaillat
LkCa 15
Rox-44
Inner disk
Inner disk
Outer
disk
Outer
disk
Optically
thin dust
within
gap
Optically
thin dust
within gap
LkCa 15
1600 K blackbody
Espaillat et al. 2007, 2008, 2009
Chagelishvili G.D.; Tevzadze A.G.;
Zahn J-P.
Hydrodynamic stability and mode
coupling in Keplerian discs
Hui Li
Trapping of the dust grains at the inner edge of the dead
zone: 3D global MHD simulations
N. Dzyurkevich, M. Flock, N. J. Turner, H. Klahr, Th. Henning
Experiment:
3D proto-planetary disk model (2 -10 AU),
Magneto-driven turbulence (MRI).
R < 4.5 AU : MRI-active zone;
R > 4.5 AU : ‘dead’ zone (magnetic dissipation).
Question: Can pressure trap occur at the
inner edge of the dead zone?
Results:
1. Reynolds stress dominates in the dead zone;
2. Long-living density rings are created 1st at
the edge of the dead zone, 2nd within MRIactive zone;
3. Super-keplerian rotation of the gas occurs,
accompanied by the pressure traps;
4. Density ring in active zone is correlated with
magnetic ‘butterfly’ structures.
Workshop “The Dynamics of Disk and Planets” Cambridge 2009
Modes in vertically stratified discs
George Mamatsashvili, Supervisor: Dr. Ken Rice
Institute for Astronomy, University of Edinburgh
1. Influence of self-gravity on p, g, and r-modes of stratified discs
We investigate the dispersion relation properties and structure (eigenfunctions) of p,g and rmodes of stratified polytrophic discs in the presence of self-gravity.
Results: only r-modes can become gravitationally unstable
below a certain value of three-dimensional Toomre’s
parameter.
p and g-modes are stable with eigenfrequencies
reduced/shifted due to self-gravity, but never
negative/unstable
Dispersion relation for r-modes
2. Linear coupling of density waves and convection
Here we investigate the linear mechanism of generation of density waves by convectively
unstable mode in a stratified disc (neglecting self-gravity) in the shearing box
Results: When the vertical scale of perturbations is of the
order of disc scale height, initially purely convective
mode is able to generate density waves
Evolution of pressure and entropy shear waves. When the radial wavenumber
crosses zero point abrupt generation of oscillations (density waves) are observed
in pressure evolution
Convergence in N-body simulations of
planetesimal formation
Hanno Rein, Geoffroy Lesur, Zoe M. Leinhardt
Wrong!
Why?
Kevin Flaherty; James Muzerolle
Mid-Infrared Variability of Transition
Disks
Planet Formation in Misaligned Binary Systems
Moritz M. Fragner & Richard P. Nelson
-
The disc precesses as a rigid body
around the angular momentum vector
of the binary system
-
A thin disc with high viscosity develops
a differential twist
-
Relative velocities between
planetesimals are too high to allow
growth via collisions
Formation Environment of the Galilean Moons
Man Hoi Lee, Neal J. Turner, T. Sano
• Criteria for dead zone from chemical network calculations.
Minimum Mass Subnebula models
Magnetically dead everywhere, except
very high in the upper layers.
Improved Gas-starved Subnebula
models with temperature
dependent opacity
• Similar to solar nebula models:
– No dead zone in the outer
regions.
– Dead zone plus active surface
layers in the inner regions.
Markus Flaig; Ralf Kissmann
MRI Turbulence in Radiative
Protoplanetary Discs
On the Saturation of the MRI in Non-Ideal MHD
Martin Pessah - IAS; J. Goodman - Princeton; C.K. Chan - ITC, Harvard
Studied spectrum of
secondary instabilities
that feed off the MRI in
non-ideal MHD
Understood relevance of
Kelvin-Helmholtz &
Tearing Modes and
proposed a way to
estimate MRI saturation
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The Dynamics of Discs and Planets - 17-21 August, 2009 - Isaac Newton Institute for Mathematical Sciences - Cambridge
Water ice on
the disk surface
Mitsuhiko Honda
Subaru/CIAO coronagraph image of
the disk around HD142527
No ice feature
HD142527 total
H2O ice absorption
Disk scattered light
(Honda et al. 2009)
Accretion of Solid Material on
Planets
Natalie Raettig
• Gas Disk with FULL
Radiation Hydrodynamics
• 30 MEarth Planet
embedded
• Model Particle Behavior
with Restricted-3-Body
method
Paul Clark
The early stages of disc formation in
young stellar clusters.
Shantanu Basu; Eduard I.
Vorobyov
Self-Consistent Formation and Longterm Evolution of Circumstellar Disks
Astrocatalysis and Protostellar Disk Evolution
Snytnikov V., Kuksheva E., Stadnichenko O., Stoynovskaya O.
Boreskov Institute of Catalysis, Novosibirsk State University
[email protected]
Dust
Protostar with circumstellar disk
Gas
C, O, N are the most abundant elements in space after H and He. The evolution of
protoplanetary disks connected with organic compounds. The astrocatalysis indicates the
protostellar disk as place of the organic substance synthesis from simple molecules on the
dust catalyst. The synthesis of the major mass of organic compounds corresponds to the
stage of the formation of primary bodies in the Solar system. The main components of the
primary bodies and protoplanets were organic compounds. Formation of bodies occurred as
a result of collective gravitational instability with the simultaneous assembly of numerous
small bodies. Results of computer simulation are used to determine conditions of organic
compound synthesis.
Computer Simulation of Protoplanetary Disk
Initial Stages
Stadnichenko Olga, Snytnikov Valeriy
Novosibirsk, Russia
Purpose: Investigation of disks
forming and long-term density
perturbations in circumstellar disk.
Rotating cloud
Equatorial section
Meridian section
Use: Unsteady 3D models of selfgravitating gas dynamics. Euler and
Poisson equations.
Initial stages of circumstellar disk
Equatorial section
Meridian section
A New Scheme to Solve Gas Disks around Stars
 

T. Hanawa
(Chiba U.)
 t
Ex. 1: Accretion from circumbinary disk
u r , t  w r  v r,
to unequal mass binary
Velocity = Reference + Residual
Gravity is canceled by the
reference velocity!
Ex. 2: V4046 Sgr = Nearly
Equal Mass Binary
Hot Spots
Tristen Hayfield; Lucio Mayer
A comparison of early disc properties
in isolated and binary systems.
Long-term Evolution of Protostellar and Protoplanetary Disks:
layered accretion with infall
Zhaohuan Zhu, Lee Hartmann, Nuria Calvet (U. of Michigan),
Charles F. Gammie (U. of Illinois), Jonathan C. McKinney (Stanford/KIPAC)
Layered disk accretion with infall from a rotating BE sphere
Infall
Layered accretion
Ω
2-D simulation for FU Ori outbursts
(Desch 2007)
θ
(Andrews et al. 2009)
0.1 AU
R
1 AU
(Zhu et al. 2009)