Curve of Growth for α Persei.

Abstract

view Abstract Citations (4) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Curve of Growth for α Persei. Steel, Helen R. Abstract Equivalent widths of 403 lines on McDonald coudé spectrograms of a Persei and Menzel and Gold- berg's solar log X~ values provide data for a curve of growth of a Persei, an F5 supergiant. The excitation temperature derived for neutral iron is 44000. The parameters of the theoretical curve, fitted to the observational curve of growth, are a velocity of 3.7 km/sec and a damping constant (P/u) of 1.2 X 1O~. So far as observational and theoretical data permit, the numbers of the different types of atoms and ions in a centimeter-square column above the photosphere are determined. The electron pressure at the base of the reversing layer is derived from the product of the number of electrons in a centimeter-square column above the photosphere, the average mass of the atoms, and the surface gravity. For a Persei, this method, with assumptions about the degree of ionization and the abundances of some elements, gives an electron pressure of 4.7 dynes/cm2. The electron pressure at the base of the solar reversing layer, by the same method, is 40 dynes/cm2. The validity of the assumptions is investigated, and the sensitivity of the pressure to the temperature is shown. The application of the observationally determined numbers of atoms in the Saha equation indicates that, in the atmosphere of a Persei, either the ionization or excitation temperature, or both, cannot be the same for silicon and titanium. A similar phenomenon has been found for the solar chromosphere Publication: The Astrophysical Journal Pub Date: July 1945 DOI: 10.1086/144738 Bibcode: 1945ApJ...102...43S full text sources ADS |