Binary system wind capture problem
Binary system wind capture problem |
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New runs. Bluegene, 5amr, wind injection region=.5 (instead of 1 as it was before).
Run A: 25 AU, 5 km/s
Run B: 25 AU, 30 km/s
Run C: 5 AU, 5 km/s
Run D: 5 AU, 30 km/s
Density logarithmic isosurfaces showing the formation of a TILTED ACCRETION DISK about the secondary star.
32^3+3amr, separation=25 AU, AGB wind speed is 20km/s (which is twice as fast as the 21 June post below).
Left (right) panels are parallel (perpendicular) to the orbital plane.
Mastrodemos & Morris 1998 (pp 497) “ Another result ..., not conclusive at this stage, ... suggest the possibility that some of these disks at relatively larger binary separations may be susceptible to warping.”
The images below shows gas flow streamlines (blue tubes) in the vicinities of the secondary star at 1, 2, ..., 9 orbital periods. The line of sight is perpendicular to the orbital plane. The small top right panel show a farther view of the binaries. Also in light blue (in the large zoom panel), a logarithmic density iso-surface that shows the bulk shape of the disk. It is evident that the disk is neither parallel to the orbital plane not perpendicular to the line that goes through the stars centers.
m1(AGB)=1.5Msun; MdotAGB=1x10-5Msun/yr; vAGB ~ 15 km/s; m2=1Msun; separation=25AU.
Slice thought the z=0 plane.
Mastrodemos & Morris 1998 (pp 321): “The limiting binary separation beyond which accretion disks can no longer form has not been reached in this work. If we extrapolate from our results, however, accretion disks must form at greater binary separation than we have investigated; for example, at a binary separation of 10Rp, with Rp = 452.4 Rsun, and even if we assume that the wind at this distance has already reached the typical terminal velocity of 15 km s-1, the ratio of orbital to wind velocity is 0.69 and Racc = 2.55. Compared with M4, this ratio of orbital to wind velocity is 10% smaller, but Racc is 45% larger. We expect that density and velocity gradients across Racc are such that a disk at least comparable in size to that of M4, would form. We therefore anticipate that for a 1 Msun secondary the limiting binary separation for disk formation should be greater than 21 AU =10Rp.”
Some previous simulations of accretion disk formation in binaries.
25 apr 2011
Click in the image below.
The movies above and below are very similar, yet the separation of the stars in the top panel is twice as long as the separation in the bottom panel.
Also, the wind velocity in the top panel is 75% of the velocity in the bottom panel.
We can form an accretion disk about the secondary star!. Click in the image below.
