Stellar Spectrophotometry from above the Atmosphere.

Instrumentation was flown in an Aerobee rocket to obtain stellar spectra in the ultraviolet. Stars of spectral type F0 Ia to 0Sf and WC7 were observed from X 1600 to X 4000. Satisfactory agreement between theoretical model atmospheres and the observations was obtained for the F0 Ia star throughout the observed spectrum and for the earlier stars down to X 2600. Below X 2400 there is a fundamental disagreement between the observations and theory for the hotter stars. It appears that the source of this disagreement is in the atmosphere of the star, and the suggestion is made that it is due to quasi-molecular absorption by various combinations of hydrogen and helium atoms and ions. Attention is drawn to the changes that are necessary in the interstellar radiation field.