X-ray line emission from sco X-1

THE emission of line radiation from hot optically thin plasmas is discussed by Tucker and Gould¹, who find that line emission should be significant for plasma temperatures of 5 × 10⁷ K. Calculations of line strengths were carried out by Tucker for three models of Sco X-1, assuming different compositions. As an example, assuming cosmic abundance, the predicted energy in line radiation from Fe⁺²⁴ and Fe⁺²⁵ is equal to 1/100 of the total radiated energy between 2 and 8 (ref. 2). In a high density plasma, however, the predictions must be modified to take account of electron scattering.