The argument of binarity and others

A point under debate is whether L2 pup is a binary system.

If the orbit is 2 AU, and period is half year (which is approximately the case for L2 pup), M should be 32 . So it is not likely that the variation in apparent magnitude is associated with the orbital period of the binary. So the variation in brightness is not a evidence for the existence of binary system.

The pro argument is, the specific angular momentum of keplerian orbit:

and for a radius of 0.5 AU AGB, this l is 10 times larger at 50 AU radii. AGB star is very slow rotator, the difference of l is huge between the surface of the AGB and the circumstellar disk. So there should be some mechanism to transfer angular momentum to the dust and gas. Binary system is a possible answer.

One may say there can be some poloidal magnetic field that extend to several AU of the AGB star, I do not know if this magnetic field is possible in a post-AGB star. Also, whether this poloidal field is effective enough to give the weakly polarized material angular momentum.

The main points in this paper may include:

  1. Binary picture is suitable in L2 pup by the argument of specific angular momentum.
  1. Hydrodynamically, stable circumstellar disk is to be found around the binary system.
  1. Radiation images matches in V and N bands.
  1. A discussion of SED. (maybe include a prediction of long wavelength result?) I am not sure what to claim in this part because there is some difference in my results and the observed results.

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