Recent content by Getterdog

Thanks, these get me closer. I may have to contact the author. I had the impression it was more than just differential scattering of the stokes parameters. But again thanks. John

I’ve bee reading through “Introduction to spectropolarimetry” by del Toro Iniesta and he mentions Faraday pulsation as a mechanism causing mixing of stokes components in the radiative transfer matrix. This is not rotation, that is separate. Any idea what this is? Thanks john

Yes, it absorption. There is a nice chapter in “Interpreting astronomical spectra” by D. Emerson on micro processes contributing to spectra, so it is relevant. I did find a good mathematical discussion of free free absorption which is the same as inverse bremsstralung. This led me to Kramers...

maybe a better starting question is under what stellar conditions would we expect inverse bremsstralung to be a significant factor? Has this been worked out In terms of electron density, intensity of radiation field ect?

There are lots of diagrams showing bremsstralung as a deflection of an electron by a nucleus but none of inverse bremsstralung. Does the inverse process I.e. photon absorption only depend on the direction of the deflection by the nucleus? If not ,what determines wether the electron will absorb...

Thanks. I’ll drop the bone for now😊I found a nice set of lectures on MIT open courseware on the golden rule. So that should help. Thanks again.

Sorry to be a sort of dog with a bone .I do astro-spectroscopy (non-professional) and do a lot of outreach for our astronomy organization. I realized I need a much deeper understanding of thermal radiation beyond the usual cavity black body thermal equilibrium approach. I do have several books...

Must the perturbing potential be a sinusoidal ‘‘em field or could it be collisions?

From Fermi’s rule there must be a continuum of eigenstates into which the transition can occur. This requires an oscillating Hamiltonian. How do we get that? Is this referring to the radiation field? A full treatment would involve the tensor product of the radiation field and the atom. So the...

I guess simply put,how does thermal motion create a more or less continuous radiation field. The answer at least in wiki is that it causes dipole oscillation in the atoms I presume.,assuming the are no free electrons. That is or was my ”hang up”. Now what that means in the quantum treatment I...

According to some grad lectures I’ve been watching, line transition strength is due to the dipole moment between orbitals. So the frequency spread may be due to interruption of this due to collisions?

My photonics text gives an interesting explanation of collisional broadening in that collisions change the phase of normal lifetime emissions and in doing so creates Fourier transform effect with spreading of the spectrum. How this plays into this I’m not sure. The atomic dipole oscillation...

I just ran across this, that thermal motion causes dipole oscillation and causes charge acceleration. With low free electron density the dipole assumes greater importance.so the dipole oscillation takes place completely within the atom? How does that work? Do collisions change the dipole moment...

My question is this. The photosphere is considered close to a continuous black body spectrum. What we observe is the stellar atmosphere doing is job of absorption and in some case emission. I am asking is what are the micro-mechanisms causing the thermal curve in a cool star, less than 10000 K...

I should have said accelerated or deaccelerated. Again, my questions pertain to stars less than 10,000K, below the ionization of hydrogen And in the visible range only. Bremstalung is soft Xray, vibrational and rotational modes are infrared. Free bound transitions should be minimal with low...