Single and Binary

Start with single star. The mass loss rate vary wish time as (increase to 10 times at time=1.5 and reduce to 1/10 at time=3.0):

and I fix the velocity at certain radius so that mass loss rate is proportional to wind density. The velocity at exact radius is obtained by solving:

numerically. From isothermal condition(2000 K throughout space) we can get the velocity that certain radius.

Under these conditions, the single star simulation become:

(Picture on the left is rho + vector v, picture on the right is speed + vector v)

single.gif​

Pick out the magnitude of velocity on x axis:

lineout.gif​

The relative difference of final velocity to the solution from Parker's stellar wind model is around 5%.

Problem 1: It is not symmetric.

Problem 2: When the star has relatively low mass loss rate, the wind speed profile does not meet the Parker's solution and the stellar structure behaves like a bubble. Either there is some threshold for this boundary condition or something worse is out there.

Problem 3: The speed profile plot of x axis does not match the color plot at small radius.

Phenomenon: It already has some fall back behavior.

Then we put a secondary star near the primary star and let they do circular motion. Their separation is 3.999 AU. The mass of them are and respectively.

zoomout.gif​

zoomin.gif​

Problem: The CFL number blow up.

High CFL - restarting step. 0.43877E+07 > 0.10000E+03

forrtl: severe (174): SIGSEGV, segmentation fault occurred

When there is only the primary star, this does not occur, but when I add the secondary, it does.

The fall back phenomenon is not obvious at this time frame.

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