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Philip A. Stahl

I specialize in stellar and solar astrophysics. Can answer questions pertaining to these areas, including: stellar structure and evolution, HR diagrams, binary systems, collapsars (black holes, neutron stars) stellar atmospheres and the spectroscopic analysis of stars – as well as the magnetohydrodynamics of sunspots and solar flares. Sorry – No homework problems done or research projects! I will provide hints on solutions. No nonsense questions accepted, i.e. pertaining to astrology, or 'UFOs' or overly speculative questions: 'traveling through or near black holes, worm holes, time travel etc. Absolutely NO questions based on the twaddle at this Canadian site: purporting to show a "new physics". Do not waste my time or yours by wasting bandwidith with reference to such bunkum.

Dr. Stephen O. Nelson

Fusion, solar flares, cosmic rays, radiation in space, and stellar physics questions. Generally, nuclear-related astrophysics, but I can usually point you in the right direction if it's not nuclear-related or if it's nuclear but not astrophysics.

Recent Answers

2016-12-10 Experimental evidence for Universe Expansion:

Hello,    First, it is incorrect to refer to "most stellar objects” receding from each other in the context of red shifts and indeed in terms of cosmic expansion. The reason is that the recessional velocities

2016-12-01 superfluidity:

Superfluidity is a state where a fluid can flow with no viscosity,  like liquid helium below 4 Kelvin.  Normal fluids need work to pump against viscous resistance due to molecular collisions, like water

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