Characteristics of quiet Sun cell and network brightenings

Citation
Lk. Harra et al., Characteristics of quiet Sun cell and network brightenings, ASTRON ASTR, 362(1), 2000, pp. 371-378
Citations number
41
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
00046361 → ACNP
Volume
362
Issue
1
Year of publication
2000
Pages
371 - 378
Database
ISI
SICI code
0004-6361(200010)362:1<371:COQSCA>2.0.ZU;2-4
Abstract
Extreme ultraviolet observations of the quiet Sun are made with the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observat ory (SOHO). It has been previously noted that frequent transition region br ightenings occur in both the bright network and dark cell regions. Analysin g 1125 events, we determined the characteristics of the brightenings in the cell and network regions which include the duration, energy, and intensity increase above the background. Network brightenings are found to be larger than cell events occurring with a mean duration of 150 s and releasing an average of 10(26.9) ergs per event. Cell brightenings, on the other hand, l ast for an average of 96 s and release 10(25.8) ergs per event. It has also been found that the distribution of energy is a power-law which is differe nt in the cell (gamma =2.5) and network (gamma =1.5) regions. When the enti re quiet Sun region is analysed the value of gamma is 1.7. The number of ev ents per CDS pixel is approximately the same, and a histogram of the ratio ([peak value - background]/background) shows similar values for both the ce ll and network. It is important to analyse the cell and network regions sep arately in the context of coronal heating by such small flare-like events.