HI umop,
Your are correct. the spectra of a planetary is very narrow so it appears as a point source using my crude method, but the stars do show a colored Rainbow Spectrum, its just so small and faint, that no absorption or emmission lines are visible, since a lot of planetary nebulas are so small and, are hard to distinguish from background stars, this method easily allows me to differentiate which ones are stars in my field of view.
But a high Magnification is needed to see the Rainbow Spectrum of Stars using this method, the More Magnification, the more the Spread of the Stars Spectrum.
Dennis
