EUV spectral line profiles in polar coronal holes from 1.3 to 3.0 R⊙

Spectral line profiles have been measured for H I lambda 1216, O VI lambda lambda 1032, 1037, and Mg x lambda 625 in a polar coronal hole observed during 1997 September 15-29, at projected heliographic heights rho between 1.34 and 2.0 R.. Observations of H I lambda 1216 and the O VI doublet from 1997 January for rho = 1.5-3.0 R. are provided for comparison. The O VI lines are well fit to a narrow and broad component which appear to be associated with regions of higher and lower spectral radiance, respectively. The narrow components dominate at low heights and become a small fraction of the lines at higher heights. Mg x lambda 625 is observed to have a narrow component at rho = 1.34 R. which accounts for only a small fraction of the observed spectral radiance. In the case of the broad components, the values of v(1/e) for O VI are only slightly larger than those for H I at rho = 1.34 R. but are significantly larger at rho = 1.5 R. and much larger for rho > 1.75 R.. In contrast, the Mg x values are less than those of H I up to 1.75 and then increase rapidly up to at least rho = 2.0 R. but never reach the values of O VI.