Structure and spectrum of quiescent prominences. III - Application of theoretical models in helium abundance determinations

Abstract

The solar helium abundance has been investigated by using spectra of quiescent prominences. The physical parameters (T, P, y, xi, M) describing an isothermal and isobaric model of the prominence can be determined from observations of hydrogen, helium, and ionized calcium lines. Given these parameters, it may be shown that low values of the helium abundance, such as those inferred from solar wind data, are inconsistent with the prominence data. The helium-to-hydrogen ratio is indicated to be 0.10 + or - 0.025 by number.