This instrument may be used to photograph spectra, and is particularly well adapted for use with SCT's. Here are some of the stars I've been observing recently including descriptions of their spectra. He was the first person I knew with one of these spectroscopes, and blazed the way for my understanding by writing comprehensive articles in the San Francisco Amateur Astronomers. Spectral lines are formed by electrons jumping between different energy levels in the atoms in the star's outer layers. Enough electrons jumping between any two energy levels of a given element will result in a spectral emission or absorption line at a characteristic wavelength.
Cool stars have less atomic collisions and have weaker absorption lines.
Hot stars are hopping with frequent atomic collisions which prevent stable molecules, and thus prevent the dark molecular bands. O stars - sorry, no hot hot blue stars of significant magnitude were visible or of a high enough magnitude for spectral detection these nights. The three Orion belt stars are O class, so we'll observe them later in the year. What we would see if we could is ionized helium and the hydrogen lines weak but still prominent. Neutral helium, with stronger hydrogen lines are present.