I have been reading an article about the interaction of a planet within a pulsar wind. However I got confused about some of the velocities and reference frames.
There are two reference frames:
Observer's frame: Neutron star at rest and since the planet velocity is small compared to the wind velocity, we may consider the planet to be at rest wrt the neutron star, except when discussing the planet's motion. Hence we may consider the planet's rest frame as the the observer's frame.
Wind's frame: Unperturbed wind's instantaneous rest frame in the vicinity of the planet.
So I have the following questions:
What is the difference between the wind's velocity and the fluid velocity?
Is the wind velocity the velocity of the plasma as a whole with respect to the observer's frame?
Is the fluid's velocity simply the velocity of its center of mass in the observer's frame? Hence fluid's velocity is the same as the wind's velocity
When they talk about a relativistic plasma, does it mean the plasma as a whole with respect to an inertial observer, or the motion of the average particles?
Is the usual Alfven velocity calculated in the wind's rest frame?
Thank you
