This hit a nerve: the 21 cm hyperfine line of neutral atomic hydrogen
is NOT a recombination line.
Ed Shaya wrote:
> ...
> I don't understand why there are so many TopConcepts, most of which have
> many layers of broader things above it.
> For instance _21_cm_line is a top concept, yet broader is
> radio_recombination_lines, broader is recombination_lines, broader is
> emission_lines, broader is specral_lines. I would perhaps accept
> spectral_lines as a TopConcept.
>
> ...
Arnold H. Rots Chandra X-ray Science Center Smithsonian Astrophysical Observatory tel: +1 617 496 7701 60 Garden Street, MS 67 fax: +1 617 495 7356 Cambridge, MA 02138 arots-at-head.cfa.harvard.edu USA http://hea-www.harvard.edu/~arots/ --------------------------------------------------------------------------Received on 2007-10-05Z17:42:58