Bangabandhu Sheikh Mujib Medical University
Question
Asked 29 March 2016
What is the role of anisotropy in the dynamic modeling of star ?
astrophysicst
What is the role of anisotropy in the dynamic modeling of star. For realistic modeling of star what should be the trend of anisotropy from center to boundary.
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All Answers (15)
National Defence Academy, Khadakwasla, Pune, India
Dear Prof. Herrera, since $p_t$ acts perpendicular to $p_r$, does it mean that $p_t$ will produce a rotational motion on the particles at interior? What will be the effect of anisotropy on a collapsing star?
University of Salamanca
No, rotations are excluded by the spherical symmetry. (in the case you are considering such a case. The effect of anisotropy consists in the appearance of an additional "force" term, besides the pressure gradient.
University of Salamanca
The above mentioned force term, of course, is directed along the radial direction.
National Defence Academy, Khadakwasla, Pune, India
Prof. Herrera, that means, due to the presence of anisotropy, the collapse will be delayed ?
National Defence Academy, Khadakwasla, Pune, India
Thank you so much Prof. Herrera. This idea seems to agree with our new solution that represents a collapsing star with non-zero anisotropy. We have analysed the time evolution of all the physical quantities and found to delayed due to anisotropy. Again we found more anisotropy implies more delayed.
SSJ UNIVERSITY ALMORA
Dear sir, anisotropy may or may not delay the collapse rate it depends on type of anisotropy as said by Prof. Herrera i.e. radial pressure is greater or less than the tangential pressure.
National Defence Academy, Khadakwasla, Pune, India
Here pr < pt, i.e. in TOV equation, the force due to anisotropy 2(pt-pr)/r > 0 and thus exert an outward force. Therefore it is clearly seen that positive anisotropy force will delay the collapsing possess.
University of Oregon
I think everyone is forgetting that the interior of stars represents a complex plasma in its physics more than an ideal gas under hydrostatic equilibrium. Yes there is no LARGE SCALE asymmetry but there are important small scale effects.
1. We do know something about seismicity in the solar fluid through the solar helioseismology project. Bulk internal movements, which can move significant amounts of mass, can produce temporal anisotropies.
2. The role that magnetic fields play in the internal structures of stars is virtually unknown and may cause important effects
Also, in the latter part of stellar evolution when the core is degenerate there may be some important effects as well
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