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Coronal loop oscillations and diagnostics with Hinode/EIS

Taroyan, Y. and Bradshaw, S. (2008) Coronal loop oscillations and diagnostics with Hinode/EIS. Astronomy and Astrophysics, 481 (1). pp. 247-252. ISSN 1432-0746

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Context.Standing slow (acoustic) waves commonly observed in hot coronal loops offer a unique opportunity to understand the properties of the coronal plasma. The lack of evidence for similar oscillations in cooler loops is still a puzzle. Aims.The high cadence EIS instrument on board recently launched Hinode has the capability to detect wave motion in EUV lines both in the imaging and spectroscopy modes. The paper aims to establish the distinct characteristics of standing and propagating acoustic waves and to predict their footprints in EIS data. Methods.A 1D hydrodynamic loop model is used and the consequences of various types of heating pulses are examined. In each case, the resulting hydrodynamic evolution of the loop is converted into observables using a selection of available EIS spectral lines and windows. Results.Propagating/standing acoustic waves are a natural response of the loop plasma to impulsive heating. Synthetic EIS observations of such waves are presented both in the imaging and spectroscopy modes. The waves are best seen and identified in spectroscopy mode observations. It is shown that the intensity oscillations, unlike the Doppler shift oscillations, continuously suffer phase shifts due to heating and cooling of the plasma. It is therefore important to beware of this effect when interpreting the nature of the observed waves.

Item Type: Article
Copyright, Publisher and Additional Information: © ESO 2008. Reproduced in accordance with the publisher's self-archiving policy.
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Depositing User: Mrs Megan Hobbs
Date Deposited: 16 Mar 2010 19:02
Last Modified: 17 Nov 2015 06:31
Published Version: http://dx.doi.org/10.1051/0004-6361:20078610
Status: Published
Publisher: EDP Sciences
Refereed: Yes
Identification Number: 10.1051/0004-6361:20078610
URI: http://eprints.whiterose.ac.uk/id/eprint/10683

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