The contours of helium lines in stellar spectra.

Abstract

view Abstract Citations (4) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The contours of helium lines in stellar spectra. Elvey, C. T. Abstract The contours of He 4472 and He 4388 have been obtained for twenty-eight stars from spectrograms made with the three-prism spectrograph of the Yerkes Observatory, and analyzed with the registering microphotometer. The contours can be represented by an equation of the simple exponential type. The presence of the Stark effect is shown by the asymmetry of He 4388 and by the "forbidden" line X 4470 of helium in the violet wing of He 4472. "Dish-shaped" contours of the lines in the spectra of i6 X Aqi., 4 ~ Cor., i~ q Tau., On., and 22 X Cep. indicate axial rotation of these stars. By Mime's theory, logarithms of the number of atoms responsible for producing an absorption line are computed for various assumptions of the physical properties of the stars. These are shown in the form of curves by plots of log N~ against the tempera- ture. The number of atoms NHf is determined for each star with use of Unsold's theory. To eliminate the Stark effect and the broadening due to rotation, NHf is determined by comparing the areas of the observed contours with those given by theory. A value of 0.1 was arbitrarily chosen forf, and the resulting numbers of atoms have been compared with the curves computed from Milne's theory. The observations support the assump- tion that the coefficient of absorption varies with the pressure, rather than that it is a constant. The observations indicate pressures of 783 dynes/cm2 to 9270 dynes/cm2 for g equal to ~ cm/sec.,2 the temperatures being from 10,0000 to 30,000°. For g equal to 10 the pressures are o.i as large Publication: The Astrophysical Journal Pub Date: October 1929 DOI: 10.1086/143211 Bibcode: 1929ApJ....70..141E full text sources ADS |