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Astronomy & Astrophysics manuscript no. aa3532-05 (DOI: will be inserted by hand later)
 

Summary: Astronomy & Astrophysics manuscript no. aa3532-05
(DOI: will be inserted by hand later)
The extent of 3-min oscillations in regions other than sunspot
plumes
Chia-Hsien Lin1, D. Banerjee2, J.G. Doyle1, and E. O'Shea1
1
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2
Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India
the date of receipt and acceptance should be inserted later
Abstract. 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 A, Mg x 625 A, O v 629 A, and He i 522 A. The periods of the strongest oscillations
in these lines were 1020 min. After the dominant 1020 min oscillations were filtered out from these lines,
only O v 629 A 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.

  

Source: Armagh Observatory

 

Collections: Physics