Stellar Spectra in the Far Ultra-Violet

Abstract

STELLAR spectra cannot be studied in the far ultra-violet spectral region, because the earth's atmosphere has too strong an absorption beyond about 3000 A., due to the amount of ozone in the upper atmosphere. There is no doubt that this ozone is formed by the photochemical action of the sun's radiation. Most of this ozone is at a height of 45–50 km., although the measurements of Dobson and his co-workers show that perhaps about 30 per cent of this ozone diffuses to deeper layers, probably to 20 km. or lower. On the other hand, we can suppose that in the higher layers (100 km. and more) less ozone will be formed, corresponding to the lower pressure.