•
•From
theory:
–Pressure
(P) and density (r) must increase with depth
•Weight
of overlying gas compresses lower material -- “Hydrostatic
equilibrium”
–Temperature (T) must increase with depth
•Energy
is flowing out of the sun – and it flows from hot to cold -- so hot
inside
–Numerical
modeling of details let us calculate T(r), r(r), P(r)
–
•From
observations of “oscillations” or “solar
seismology”
–The sun oscillates like a bell (or the air
in an organ pipe)
–The
frequency depends upon sound speed, which depends upon T(r), r(r), P(r)
–Observations
from “Global Oscillation Network Group (GONG) telescopes.
–
•From
interpreting the spectrum using Kirchoff’s laws
–The Sun looks like continuous emission: Solid
or hot dense gas
–Absorption
lines in the spectrum: Cooler gas between us and the dense gas