view Abstract Citations (21) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Line Broadening in Chromospheric Spicules. Athay, R. Grant Abstract Profiles of the H, K, X 8498 and X 8542 lines of Ca ii, H of hydrogen and 7772 and 7774 lines of O i for chromospheric spicules are used in conjunction with earlier observations of hydrogen, helium, and Ca IL line profiles to investigate the line-broadening mechanisms. The analysis tends to confirm an earlier suggestion that the Ca ii lines are broadened, in part, by a macroscopic motion of the ions not shared by the neutral atoms and that this additional velocity may arise from an interaction between the systematic spicule motion and magnetic lines of force. The analysis suggests that in optically thin lines the halfwidth increases slowly with height in spicules, which is borne out by earlier observations of the D3 line. In the H and K lines and in Ha, which are broadened, in part, by self-absorption, the half-widths are observed to decrease with height. At a mean height of about 5000 km, the kinetic temperature in spicules is found to be of the order of 50000 from Hp, H , and D3 profiles. The presence of Ca ii emission in the spicules suggests the possibility of regions of lower temperature resulting from temperature gradients perpendicular to the spicule axes. Publication: The Astrophysical Journal Pub Date: November 1961 DOI: 10.1086/147202 Bibcode: 1961ApJ...134..756A full text sources ADS |