EDP Sciences
Free access
Volume 384, Number 1, March II 2002
Page(s) 303 - 316
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20011819

A&A 384, 303-316 (2002)
DOI: 10.1051/0004-6361:20011819

An erupting macrospicule

Characteristics derived from SOHO-CDS spectroscopic observations
S. Parenti, B. J. I. Bromage and G. E. Bromage

Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK

(Received 9 November 2001 / Accepted 20 December 2001 )

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 10 8 cm -3 and a temperature rising from $0.95 \times 10^6$ K near the limb to $1.2
\times 10^6$  K at about $4.7 \times 10^4$ 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 $3 \times
10^4$  km above the limb. The macrospicule was found to have a density of the order of 10 10 cm -3 and a temperature of about $2{-}3 \times 10^5$ 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 $6 \times 10^4$ km.

Key words: Sun: corona -- Sun: activity

Offprint request: S. Parenti, sparenti@uclan.ac.uk

© ESO 2002