Observations of Solar Doppler Shift Oscillations with the EUV Imaging Spectrometer on Hinode

TL;DR

This paper reports the detection of low-amplitude, damped Doppler shift oscillations in coronal emission lines observed with Hinode's EUV Imaging Spectrometer, providing insights into solar coronal wave phenomena.

Contribution

It presents new observations of damped oscillations at lower temperatures with Hinode, expanding understanding of solar coronal dynamics and wave damping mechanisms.

Findings

Oscillation amplitude ~2 km/s

Period around 35 minutes

Decay times vary with temperature

Abstract

Damped Doppler shift oscillations have been observed in emission lines from ions formed at flare temperatures with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory and with the Bragg Crystal Spectrometer on Yohkoh. This Letter reports the detection of low-amplitude damped oscillations in coronal emission lines formed at much lower temperatures observed with the EUV Imaging Spectrometer on the Hinode satellite. The oscillations have an amplitude of about 2 km/s, and a period of around 35 min. The decay times show some evidence for a temperature dependence with the lowest temperature of formation emission line (Fe XII 195.12 Angstroms) exhibiting a decay time of about 43 min, while the highest temperature of formation emission line (Fe XV 284.16 Angstroms) shows no evidence for decay over more than two periods of the oscillation. The data appear to be consistent with slow magnetoacoustic standing waves, but may be inconsistent with conductive damping.