Volume 481, Number 1, April I 2008
Science with Hinode
|Page(s)||L41 - L44|
|Published online||04 December 2007|
Letter to the Editor
SUMER-Hinode observations of microflares: excitation of molecular hydrogen
Max-Planck Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany e-mail: email@example.com
Accepted: 20 November 2007
Context.Concentrations of H2 have been detected by SUMER in active region plage. The H2 is excited by O line emission at 1031.94 Å which, although not observed, must be brightening along with the observed transition region line, 1113.24 Å.
Aims.We investigate the excitation of H2 and demonstrate the association between the observed H2 emission and footpoints of X-ray microflares.
Methods.We have made co-ordinated observations of active region plage with the spectrometer SUMER/SoHO in lines of H2 1119.10 Å and 1113.24 Å and with XRT/Hinode X-ray and SOT/Hinode Ca filters.
Results.In six hours of observation, six of the seven H2 events seen occurred near a footpoint of a brightening X-ray loop. The seventh is associated with an unusually strong plasma outflow.
Conclusions.Microflare energy dissipation heats the chromosphere, reducing its opacity, so that O microflare emission is able to reach the lower layers of the chromosphere and excite the H2.
Key words: molecular processes / Sun: activity / Sun: flares / Sun: UV radiation
© ESO, 2008
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