Hi Dominic, Amazing! I transferred to Alan Knapp’s group in 2002 (or thereabouts) in the twilight of my career with Philips, avoiding redundancy in the process. I eventually took redundancy and early retirement when what was left of the lab moved to Cambridge in 2008. A sad end to what was part of a prestigeous institution that was up there (almost) with Bell labs. I had many interesting projects and conference/business trips over the years since I joined, in 1973, what was then the Mullard Research Laboratory. My happiest time was through the 1980’s to early 90’s modelling silicon power devices, computing power was increasing according to Moore’s law and the models could therefore become more and more detailed so I’m very familiar with solving thousands of sparse profiled matrix equations. I still have the software to do this (if you’re interested). It can solve (in principle) via LU decomposition any number of equations in any number of dimensions to any level of “fill in” all the way up to a direct solver using various iteration methods developed in the 1980’s (conjugate gradients, bi-conjugate gradients etc). I posted some of my work on the “legacy page” of my website http://www.thewhightstuff.co.uk.
Back to spectroscopy: I think you are referring to the principle of detailed balance in your last reply and that is what I used to determine the Einstein B coefficients but they vary too strongly between the Balmer series lines to reproduce my measurements. They are also temperature independent whereas my measurements, over a number of stars, definitley show a temperature dependance hence the reasoning leading to my equation A.4.12. Another pleasing feature of my model is that all calculated internal parameters have believeable values, the impact parameter for pressure calculation is approximately 8 Bohr radii and photon cross-sections are of the order of 10 Bohr areas.
I suppose I am looking for someone who would look at my model and say “yes this is how a ball of gas in thermal equilibrium would look spectroscopically” or “no it isn’t because….”, whether it’s a good model of any particular star is a separate question though the Sun looks to be well modelled in it’s gross features. I realise this is a big imposition on anyone so if it is of interest to you please continue this discussion via my email address ken.whight@btinternet.com and if you still live in the South East or are attending Astrofest it would be great to meet up. if it’s not of interest then thank you very much for taking the trouble to comment.
Regards
Ken Whight
British Astronomical Association
Supporting amateur astronomers since 1890