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Astronomy & Astrophysics manuscript no. madjarska c ESO 2011 May 20, 2011

Summary: Astronomy & Astrophysics manuscript no. madjarska c ESO 2011
May 20, 2011
Can coronal hole spicules reach coronal temperatures?
M.S. Madjarska, K. Vanninathan and J.G. Doyle
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
Received date, accepted date
Aims. The present study aims to provide observational evidence of whether coronal hole spicules reach coronal temperatures.
Methods. We combine multi-instrument co-observations obtained with the SUMER/SoHO and with the EIS/SOT/XRT/Hinode.
Results. The analysed three large spicules were found to be comprised of numerous thin spicules that rise, rotate, and descend
simultaneously forming a bush-like feature. Their rotation resembles the untwisting of a large flux rope. They show velocities ranging
from 50 to 250 km s-1
. We clearly associated the red- and blue-shifted emissions in transition region lines not only with rotating but
also with rising and descending plasmas. Our main result is that these spicules although very large and dynamic, are not present in
the spectral lines formed at temperatures above 300 000 K.
Conclusions. In this paper we present the analysis of three Ca ii H large spicules that are composed of numerous dynamic thin
spicules but appear as macrospicules in lower resolution EUV images. We found no coronal counterpart of these and smaller spicules.
We believe that the identification of phenomena that have very different origins as macrospicules is due to the interpretation of the
transition region emission, and especially the He ii emission, wherein both chromospheric large spicules and coronal X-ray jets are
present. We suggest that the recent observation of spicules in the coronal AIA/SDO 171 and 211 channels probably comes from


Source: Armagh Observatory


Collections: Physics