Multiple spiral branches on late AGB stars

Qian WangIowa State University

LL pagasi (Sahai 2010)

Sahai 2006

Model method

Bowen code Passing planet

+

Bowen code

• 1-D code with Lagrange zoning.• Hydrodynamic and thermodynamic equation

without magnetic field.• Atmosphere is driven by a sinusoidal piston

below photosphere.• Density dependent thermal relaxation and

Hydrogen cooling at high temperature• Radiation on dust grain and molecules

Companion characters

• The companion is on a circular orbit. • The mass of the companion ~ 10Mjupiter• The size of the companion is determined by

the average Jupiter density.• The companion has no collision cross section

but only gravity.

Model parametersMass(Msun) 1

Luminosity(Lsun) 5000

T(K) 2966

R(Rsun) 267.8

Vterminal(km/s at 18R*) 9.35km/s

Mdot(Msun/yr) 1.25e-6

Pulsation period (day) 394

Pulsation Amp.(km/s) 3.974km/s

Model parametersModel NO. Mp(Mjupit

er)D (Rstar) Porb (days) # of spirals Tss (Ppuls)

1 2 1.01889 522.43 4 60

2 5 1.01889 522.43 4 60

3 5 1.1 586.1 3 60

4 8 1.1 586.1 3 60

5 10 1.1 586.1 3 60

6 12 1.1 586.1 3 60

7 10 1.325 775.082 2 60

8 10 1.339 786.94 2 400

9 10 12.94 23640 1 60

10 20 18.187 39400 1 100

Origin of super shocksSuper shock clustering Shock speed vs Shock Density

Shock effectsStrong shocks and Temp. contour Weak shocks and Temp. Contour

Shock effectsStrong shocks and Molecular accel. contour Strong shocks and dust accel. contour

Model analysisDensity Profile at time = 700 cycles

Extended density contour of Model 5 at time = 1200 cycles

Model 6

Model 5

Model 4

Model 3

3 spiral armsDensity color map of Model 5 Kinetic Temperature map of Model 5

R(cm)

Time (cycle)

Density color map

4 spiral armsDensity color map of Model 1 Density color map of Model 2

4 spiral armsDensity Profile at time = 700 cycles Model 1 Density Profile at time = 700 cycles Model 2

2 spiral armsDensity color map of Model 7 Density color map of Model 8

2 spiral armsDensity Profile at time = 700 cycles Model 7 Density Profile at time = 700 cycles Model 8

1 spiral armDensity color map of Model 9 Density color map of Model 10

1 spiral armDensity Profile at time = 700 cycles Model 9 Density Profile at time = 700 cycles Model 10

Equation for super shocks

€

Pss =Ppuls × Porb

Porb −N × (Porb − Ppuls)

Observation results

IRC-10216 (Mauron & Huggins 2000)

Questions and suggestions

Maybe I can explain this