Posts for the month of June 2018

Magnetic fields in evolved stars

Those are the different final morphologies found using as a core model OH231 and varying the opening angle as well as the field at the stellar surface. No image "Models_OH231_Rjet1d4.png" attached to Blog: Magnetic fields in evolved stars.

Energy study in CEE simulation

New Work

Study on energy evolution and mass evolution during CEE simulation Energy movie. See note Energy_note_0626018

Nomalized energy movies

Energy Distribution X
Energy Distribution Y
Energy Distribution Z
Energy Distribution X normalized
Energy Distribution Y normalized
Energy Distribution Z normalized

Next Step

  1. Solve computational issue with original data set (Thanks to Baowei, Jonathan and Luke!)
  2. Re-simulate initial time-steps will be wanted due to the need to explain the energy jump between initial two frames
  3. Analytic solution to CEE and how different are they from simulation
  4. add mixing/convection into consideration; consider other factors (such as RLOF) that may effect energy budget.
  5. Consider Moment conservation and distribution, gaining insight to the simulation from another prospective.

Exoplanets II

Poster

Also, dress code for conferences?

MHDJetClump Module

Low-field testing results with no magnetic field for Clump

Bstar=0, Compare with Bruce's hydro result(right panel) http://www.pas.rochester.edu/~bliu/pnStudy/MHD_OH231/hydroTest/frame8_highres.png movie
Bstar=1e-5 gauss, http://www.pas.rochester.edu/~bliu/pnStudy/MHD_OH231/logRhoBz_Bstar_1e-5_frame8.png movie
Bstar=1e-4 gauss, http://www.pas.rochester.edu/~bliu/pnStudy/MHD_OH231/logRhoBz_Bstar_1e-4_frame8.png movie

Updates on recombination project

Progress and questions

  1. Set up flow equations in Mathematica
  2. Try to solve simplified cases:
    • Isothermal, with fixed x=0 or x=1
    • Adiabatic cooling
    Luke suggested there may be analytical solutions for these situations.
  3. How to calculate the recombination coefficients?

equations test03 isothermal

May be relevant to our work

PDFs in the attachment

  • [Chou&Talbot1967]
  • [Gol'dfarb&Kostygova&Luk'yanov1969]

other references are listed in the attached note from Luke

COMMON ENVELOPE SIMULATIONS: Movie Library for Paper 1

New Work

  1. Revision of paper
  2. Progress on energy project with Yisheng, Eric
  3. Progress on recombination/dust project with Amy
  4. Movies of simulations from paper 1

Some new notes on energy in CE simulations

notes on energy and envelope ejection in common envelope simulations

Movies corresponding to figures in paper

All movies are in the reference frame corotating about the secondary with the instantaneous orbital angular speed of the particles, and with the secondary at the center.

Figure 1:
Face-on density (Model A no subgrid accretion)

Figure 2:
Face-on density (Model B Krumholz accretion)

Figure 4:
Edge-on density (Model A no subgrid accretion)

Edge-on density (Model B Krumholz accretion)

Edge-on density (zoomed in) (Model A no subgrid accretion)

Edge-on density (zoomed in) (Model B Krumholz accretion)

Figure 6:
Tangential velocity with velocity vectors (Model A no subgrid accretion)

Tangential velocity with velocity vectors (Model B Krumholz accretion)

Extra Movies

Temperature (Model A no subgrid accretion)

Temperature (Model B Krumholz accretion)

Sound speed (Model A no subgrid accretion)

Sound speed (Model B Krumholz accretion)

Mach, lab frame (Model A no subgrid accretion)

Mach, lab frame (Model B Krumholz accretion)

Mach, frame corotating about secondary (Model A no subgrid accretion)

Mach, frame corotating about secondary (Model B Krumholz accretion)

Side-by-side comparison of Models A (left) and B (right) from Paper 1

Face-on density
Edge-on density
Edge-on density, zoomed
Tangential velocity
Temperature
Sound speed
Mach in lab frame
Mach in frame corotating about secondary

Next steps

  • Submit revision?
  • Testing Jonathan's new conservative jet prescription
  • Explore jet parameter space with Bondi accretion flow
  • Set up jet for CE simulation
  • Restart CE simulation with imposed jet

MHD Planetary Winds

Ran suite of simulations of anisotropic Parker type winds with magnetic fields

Update 6/4

Radiation Pressure

Still looking ok at 16 frames.

http://www.pas.rochester.edu/~adebrech/PlanetIonization/radPress/4d14_166.png

I've attached a Mathematica file with calculations for the balance point in terms of various quantities. The most questionable approximation, I believe, is that of constant density (although the radiation pressure isn't actually pushing on all of the material, I expect the momentum to transfer between the leading edge and the rest of the wind as they collide). With current parameters, the balance point is calculated to be about 1012 phot/cm2/s.

Flares

Clearly one hour at 100x steady flux is too strong of a flare. Luca's suggested 40 minutes might be a more reasonable time, and I can turn it down, as well.

http://www.pas.rochester.edu/~adebrech/PlanetIonization/flare_test1.gif

COMMON ENVELOPE SIMULATIONS

Here are some notes on putting a jet into the simulation.

Movies of outflow added to a Bondi accretion setup with

Computational units are: density scale = cm-3, time scale = yr, length scale = AU

1) Fixed grid outflow with particle at center.

  • Solution without outflow (not shown) adjusts and then is stable, approximating Bondi accretion.
  • Subgrid accretion routine is set to Krumholz.
  • Fixed grid, resolution 643
  • Box dimension L = 10 AU
  • Ambient density 105 cm-3
  • Ambient temperature 370 K
  • Outflow parameters are:

Particle%Feedback%efficiency=1d0 —> all accreted mass goes into outflow
Particle%feedback%radius=16 —> outflow set every time step in bipolar regions of radius 16 cells
Particle%feedback%rsurface=0.01d0 —> jet assumed to be launched from 0.01 solar radii from the secondary (white dwarf surface)
Particle%feedback%jefficiency=1d0 —> all of accreted angular momentum goes into outflow (so none into spin of secondary)
Particle%feedback%collimation=pi/12 —> collimation angle
Particle%feedback%T=0d0 —> made jet have zero temperature
Particle%feedback%p=1 —> parameter that determines smoothness of jet edges
particle%feedback%spin_axes=(/0d0,0d0,1d0/) —> forces outflow axis to be z axis
particle%feedback%vfact=2d0 —> jet assumed to be launched with 2 times the Keplerian speed at launch radius

xz slice of density with velocity vectors

2) Next increased box size by factor of 4 to L = 40. Base resolution 643 and 2 levels AMR. Tested solution first without outflow. Not completely stable. Not surprising because accretion radius of 4 cells is now smaller with finer resolution around particle, so Krumholz underestimates Bondi accretion rate more.

xz slice of density
xz slice of density with velocity vectors

3) Same but now added outflow and initialized particle and gas with constant velocity.
xz slice of density
xz slice of density with velocity vectors relative to moving frame

4) Similar but now initialize particle with constant velocity but not gas.
xz slice of density
xz slice of density with velocity vectors

Discussion

  • The outflow prescription seems to work okay.
  • As a next step, I could go to a CE setup but in low resolution.
  • Control case would have no outflow but Krumholz accretion turned on (Krumholz just used for testing purposes, but we will change subgrid accretion model).
  • Then same thing but with outflow also turned on.