Letter to the Editor

Coronal magnetic field measurement using loop oscillations observed by Hinode/EIS

¹ Centre for Fusion, Space and Astrophysics, Physics Department, University of Warwick, Coventry CV4 7AL, UK e-mail: [t.van-doorsselaere;v.nakariakov;erwin.verwichte]@warwick.ac.uk
² STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK e-mail: p.r.young@rl.ac.uk

Received: 13 May 2008
Accepted: 12 June 2008

Abstract

We report the first spectroscopic detection of a kink MHD oscillation of a solar coronal structure by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Japanese Hinode satellite. The detected oscillation has an amplitude of 1 km s^-1 in the Doppler shift of the FeXII 195 Å spectral line (), and a period of . The unique combination of EIS's spectroscopic and imaging abilities enables us to measure simultaneously the mass density and length of the oscillating loop. This enables us to measure directly the magnitude of the local magnetic field, the fundamental coronal plasma parameter, as , with unprecedented accuracy. This proof of concept makes EIS an exclusive instrument for the full scale implementation of the MHD coronal seismological technique.