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Author Lin, C. H. ♦ Banerjee, D. ♦ Doyle, J. G. ♦ O’Shea, E.
Source Indian Institute of Astrophysics
Content type Text
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Physics
Subject Keyword Sun:corona ♦ Sun:oscillations
Description The active region, AR0554, was observed with NIS/CDS on board SoHO to examine the extent and range of oscillations from a range of features. Among all the NIS spectral lines analysed, significant oscillations were found in Si xii 520 Å, Mg x 625 Å, O v 629 Å, and He i 522 Å. The periods of the strongest oscillations in these lines were ≈10−20 min. After the dominant 10−20 min oscillations were filtered out from these lines, only O v 629 Å showed significant (i.e. above the 95% significance level) shorter-period oscillations. Specifically, we found that weak but significant 3-min oscillations are not confined to the umbra/plume but can be seen in many bright locations. The duration of these non-umbral 3-min oscillations is mostly ≈20 min. In contrast, the 3-min oscillations within the umbra are strong and stable for longer than 50 min. The duration could be related to the size of the oscillating source region, rather than the lifetime of the oscillation. To find the possible sources of these 3-min oscillations outside of the umbra, we compared the oscillations of single pixels in different regions. The results of our comparison indicate a possible connection between the magnetic fields and the oscillations. Therefore, we suggest that 3-min oscillations may exist in many magnetic structures, but are often too weak to be seen in an unfiltered signal.
ISSN 00046361
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Institution EDP Science
Journal Astronomy and Astrophysics
Volume Number 444
Issue Number 2
Size (in Bytes) 1.77 MB
Page Count 8
Starting Page 585
Ending Page 592