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Coronal Oscillations above Sunspots? Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
 

Summary: Coronal Oscillations above Sunspots?
J.G. Doyle
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
E. Dzifcakova
Astronomical Institute, Faculty of Mathematics, Physics and Informatics,
Comenius University, Mlynska dolina, 842 48 Bratislava 4, Slovakia
M.S. Madjarska
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
now at: Mullard Space Science Laboratory, University College London, Holmbury
St Mary, Dorking, Surrey RH5 6NT
Abstract. Observational data clearly indicate the presence of 3 min oscillations in
sunspots in spectral lines covering a vast temperature range from the low chromo-
sphere to those lines normally associated with coronal temperatures. We show that
after folding in the sunspot plume emission measure distribution, the contribution
functions for lines normally formed just below 1  10 6 K are shifted to lower tem-
peratures. For example, the Fe ix 171  A line is shifted to 610 5 K for a Maxwellian
distribution and to less than 5  10 5 K with a non-Maxwellian distribution. Other
lines such as Mg ix 368  A will also be e ected. This then questions some previous
work regarding the suggested detection of 3 min oscillations in the corona above
sunspots.

  

Source: Armagh Observatory

 

Collections: Physics