On the spectroscopic detection of periodic plasma flows in loops undergoing thermal non-equilibrium. (arXiv:1912.02538v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pelouze_G/0/1/0/all/0/1">Gabriel Pelouze</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Auchere_F/0/1/0/all/0/1">Frédéric Auchère</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bocchialini_K/0/1/0/all/0/1">Karine Bocchialini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Froment_C/0/1/0/all/0/1">Clara Froment</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parenti_S/0/1/0/all/0/1">Susanna Parenti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Soubrie_E/0/1/0/all/0/1">Elie Soubrié</a>
Context: Long-period intensity pulsations were recently detected in the EUV
emission of coronal loops, and have been attributed to cycles of plasma
evaporation and condensation driven by thermal non-equilibrium (TNE). Numerical
simulations that reproduce this phenomenon also predict the formation of
periodic flows of plasma at coronal temperatures along some of the pulsating
loops. Aims: In this paper, we aim at detecting these predicted flows of
coronal-temperature plasma in pulsating loops. Methods: To this end, we use
time series of spatially resolved spectra from the EUV imaging spectrometer
(EIS) onboard Hinode, and track the evolution of the Doppler velocity in loops
in which intensity pulsations have previously been detected in images of
SDO/AIA. Results: We measure signatures of flows that are compatible with the
simulations, but only in a fraction of the observed events. We demonstrate that
this low detection rate can be explained by line of sight ambiguities, combined
with instrumental limitations such as low signal to noise ratio or insufficient
cadence.
Context: Long-period intensity pulsations were recently detected in the EUV
emission of coronal loops, and have been attributed to cycles of plasma
evaporation and condensation driven by thermal non-equilibrium (TNE). Numerical
simulations that reproduce this phenomenon also predict the formation of
periodic flows of plasma at coronal temperatures along some of the pulsating
loops. Aims: In this paper, we aim at detecting these predicted flows of
coronal-temperature plasma in pulsating loops. Methods: To this end, we use
time series of spatially resolved spectra from the EUV imaging spectrometer
(EIS) onboard Hinode, and track the evolution of the Doppler velocity in loops
in which intensity pulsations have previously been detected in images of
SDO/AIA. Results: We measure signatures of flows that are compatible with the
simulations, but only in a fraction of the observed events. We demonstrate that
this low detection rate can be explained by line of sight ambiguities, combined
with instrumental limitations such as low signal to noise ratio or insufficient
cadence.
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