An erupting macrospicule. Characteristics derived from SOHO-CDS spectroscopic observations
Abstract
We report results from the analysis of a sequence of SOHO/CDS observations obtained off-limb in the south polar coronal hole on 6 March 1998. Three successive data sets were obtained with the Normal Incidence Spectrometer (NIS), the first of which showed a jet-like feature visible in the chromospheric and low transition region lines. The morphological characteristics of this feature suggested it was a macrospicule. The two remaining observations of the same region indicated a quiet coronal hole with a density of 108 cm-3 and a temperature rising from 0.95 x 106 K near the limb to 1.2 x 106 K at about 4.7 x 104 km above the limb. These data were averaged and used as ``background'' for the macrospicule observation. The resulting subtracted spectra showed more details of the feature. In particular, a cloud of plasma was detected at about 3 x 104 km above the limb. The macrospicule was found to have a density of the order of 1010 cm-3 and a temperature of about 2-3 x 105 K. The initial outflow velocity near the limb was over 80 km s-1. This decreased to a terminal value of 26 km s-1 above about 6 x 104 km.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- March 2002
- DOI:
- 10.1051/0004-6361:20011819
- Bibcode:
- 2002A&A...384..303P
- Keywords:
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- SUN: CORONA;
- SUN: ACTIVITY