Recent work

I updated some movies ​https://astrobear.pas.rochester.edu/trac/blog/zchen04132015, a new one that has longer z-axis is still computing. That one proves slow AGB wind is not the key to the formation of collimated outflow but it has similar shape to the butterfly PN in Balick's paper (Balick, 1987 ApJ). On the other hand, in this paper​The Necklace: equatorial and polar outflows from the binary central star of the new planetary nebula IPHASX J194359.5+170901, they measured that the kinematic age of polar outflow is older than the equatorial structure, implying that the collimated outflow is more likely to be the polar jets from a compact secondary. Another point to mention is that to have a circumbinary disk, a binary system just require a slow wind from AGB star, either spherical or equatorial will do the work. It does not need to carry angular momentum from the rotation of the AGB star.

I read some papers mentioned by the reviewer, I found that this paper is very very useful ​2D models for dust-driven AGB star winds. The author is an expert in AGB dust formation. In this paper, he used equation of motion and energy equation to solve the fluid motion. Dust evolution is computed by moment equations (see ​Dust formation in stellar winds. IV - Heteromolecular carbon grain formation and growth and their book ​Physics and chemistry of circumstellar dust shells of chapter 14). Woitke also included radiative transfer, he assumed Local Thermal Equilibrium (LTE) to simplify his calculation (​High precision Monte Carlo radiative transfer in dusty media). I do not understand the detailed technique and Monte Carlo simulation in the paper. In his discussion, he compared his results with 1D models and simulated the case without pulsations. The nature of pulsation is nuclear reaction lying deep in the AGB star and result in a sudden jump in luminosity. The physics in this paper is much more complicated. The temperature gradient is an issue in our paper, I think this part should be modified to a more realistic model.

I am now very interested in the dust evolution. It is actually very important to AGB evolution, binary system evolution and PN evolution. Dust formation is deeply linked to the chemical composition of the star (i.e. high metalicity, C type star or O type star). Dusts absorb and scatter 30% of phontons (see ​Interstellar Dust) so it provide the much momentum in many kinds of AGB winds. its evolution is sometimes coupled with the spectral near the AGB star, especially for the optical thick case (but rare). I think a good description in dust formation in our code will let us have more physics.

As for the binary simulation, I have an idea that we can just run a simulation to mimic ​The Necklace: equatorial and polar outflows from the binary central star of the new planetary nebula IPHASX J194359.5+170901. The modification should just be add a polar outflow with high speed from the secondary before the pulsation from the AGB star. A rough estimate is that we need 112 cores * 24 hr * 30 on bluehive (the longer z-axis one need 21 days with slow stellar wind speed.)

A recent movie​

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