Transition region velocity oscillations observed by EUNIS-06


Autoria(s): Jess, D. B.; Rabin, D. M.; Thomas, R. J.; Brosius, J. W.; Mathioudakis, M.; Keenan, F. P.
Data(s)

01/08/2008

Resumo

Spectroscopic measurements of NOAA AR 10871, obtained with the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument on 2006 April 12, reveal velocity oscillations in the He II 303.8 angstrom emission line formed at T approximate to 5; 10(4) K. The oscillations appear to arise in a bright active region loop arcade about 25 '' wide which crosses the EUNIS slit. The period of these transition region oscillations is 26 +/- 4 s, coupled with a velocity amplitude of +/- 10 km s(-1), detected over four complete cycles. Similar oscillations are observed in lines formed at temperatures up to T approximate to 4; 10(5) K, but we find no evidence for the coupling of these velocity oscillations with corresponding phenomena in the corona. We interpret the detected oscillations as originating from an almost purely adiabatic plasma, and infer that they are generated by the resonant transmission of MHD waves through the lower active region atmospheres. Through the use of seismological techniques, we establish that the observed velocity oscillations display wave properties most characteristic of fast body global sausage modes.

Formato

application/pdf

Identificador

http://pure.qub.ac.uk/portal/en/publications/transition-region-velocity-oscillations-observed-by-eunis06(c48267de-c4f3-43fb-b40e-7d50516fb208).html

http://dx.doi.org/10.1086/589231

http://pure.qub.ac.uk/ws/files/16356125/0004_637X_746_2_183.pdf

Idioma(s)

eng

Direitos

info:eu-repo/semantics/openAccess

Fonte

Jess , D B , Rabin , D M , Thomas , R J , Brosius , J W , Mathioudakis , M & Keenan , F P 2008 , ' Transition region velocity oscillations observed by EUNIS-06 ' Astrophysical Journal , vol 682 , pp. 1363-1369 . DOI: 10.1086/589231

Palavras-Chave #Sun: Activity #Sun: Oscillations #Sun: Transition Region #Sun: UV Radiation #/dk/atira/pure/subjectarea/asjc/1900/1912 #Space and Planetary Science #/dk/atira/pure/subjectarea/asjc/3100/3103 #Astronomy and Astrophysics
Tipo

article