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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

2017-03-26 Question about the color of sunlight:

Your eyes do indeed not have the high-end dynamic adjustability of a camera. If you overload all the cones, of course everything appears white to your eye.  Cameras can dial back their sensitivity to the

2017-03-22 Question about the color of sunlight:

Sorry for the delay, I was overseas.  Sunlight peaks at around the yellow-green region of the spectrum if you look at its power per unit wavelength, but its peak power output is a little lower if you plot

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