Name: physical_polytrope
Description:
This IDL pro accepts the structure polytrope from the function
test_le1 and applies physical values to the scaled polytrope. It
sets the value of lambda, the central density in g/cc and the mass
of the polytrope in solar units.
Syntax:
physical_polytrope, rho_c, mass, polytrope, physical
Input:rho_c:
rho_c is an IDL floating_point > 0 which is the central density of the
polytrope in g/cc.
mass:
mass is an IDL floating_point > 0 which is the mass of the polytrope
in solar mass units.
polytrope:
polytrope is an IDL structure generated by the pro test_le1.
Documentation about this structure is found in the file
test_le1.pro.
Output:physical:
physical is an IDL structure of arrays and values described in the
items below.
physical.radial_coordinate is an IDL dblarr which is the
distance variable in the Lane-Emden equation. It has units of cm.
physical.m_xsi is an IDL dblarr which is the
enclosed mass at a particular raduis of the star. It has units of
solar mass.
physical.a is an IDL floating_point which is the polytropic unit
of length.
physical.K is an IDL floating_point which gives the constant in the
pressure/density equation of state of the polytrope.
physical.R is an IDL floating_point which is the radius of the
polytrope in cm corresponding to the first root of the Lane-Emden
equation.
physical.denstiy is an IDL dblarr which is the mass density at a
particular radius of the star. It has units of g/cc.
physical.average_density is an IDL floating_point which is the
average density of the polytrope over the radius of the star in
g/cc.
physical.mass is the mass of the polytrope in solar mass units.
physical.pressure is the force per unit area exerted by the star
at a certain radial coordinate.
Example:
The following IDL command-line sequence first
calculates a polytrope structure
of index 3. and then uses that structure to calculate the radius of
this polytrope of central density 1.e7 g/cc and mass 0.9 solar mass:
test_le1, 3., polytrope
physical_polytrope, 1.e7, 0.9, polytrope, physical
print, physical.R
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