Photoelectric observations of chromospheric sunspot oscillations. IV - The CA II H line and He I 10830 A

Abstract

view Abstract Citations (65) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric Observations of Chromospheric Sunspot Oscillations. IV. The CA II H Lines and He i lambda 10830 Lites, B. W. Abstract Simultaneous observations of profiles of He I λ10830 and the Ca II H line in sunspot umbrae have been made with the Tower telescope, echelle spectrograph, and multidiode array at the National Solar Observatory/Sunspot. These observations reveal the nature of fluid motions in the upper chromosphere during the cycle of umbral oscillations. Time sequences of profiles show that the chromospheric He I line is in weak absorption during all phases of the umbral oscillations, and that it undergoes periodic Doppler shifts of high amplitude (up to 11 km s-1). The amplitudes and waveforms of the Doppler shifts in the He I line indicate that the oscillations are frequently nonlinear (i.e., forming shocks) and therefore contribute to the heating of the upper umbral chromosphere. Publication: The Astrophysical Journal Pub Date: February 1986 DOI: 10.1086/163964 Bibcode: 1986ApJ...301.1005L Keywords: Abundance; Chromosphere; Electrophotometry; Solar Oscillations; Stellar Spectrophotometry; Sunspots; Calcium; Doppler Effect; Helium Ions; Hydrogen; Line Shape; Line Spectra; Temporal Distribution; Umbras; Solar Physics; SUN: CHROMOSPHERE; SUN: OSCILLATIONS; SUN: SUNSPOTS full text sources ADS | Related Materials (4) Part 1: 1982ApJ...253..386L Part 2: 1984ApJ...277..874L Part 3: 1986ApJ...301..992L Part 5: 1988ApJ...334.1054L