Magnetoacoustic wave propagation in off-limb polar regions

Details Magnetoacoustic wave propagation in off-limb polar regions Magnetoacoustic wave propagation in off-limb polar regions

Jun 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006a%26a...452.1059o&link_type=abstract

Astronomy and Astrophysics, Volume 452, Issue 3, June IV 2006, pp.1059-1068

Astronomy and Astrophysics

Astrophysics

19

Sun: Oscillations, Sun: Transition Region, Sun:, Atmosphere, Sun: Corona

Scientific paper

Aims.To find evidence of magnetoacoustic waves in off-limb polar regions. Methods: .Using temporal series data from the Coronal Diagnostic Spectrometer (CDS) on SOHO, we study oscillations found in radiant flux and velocity measurements from transition region and coronal spectral lines. We use Fourier techniques to measure phase delays between flux (“intensity”) oscillations and between velocity oscillations of different transition region-corona and corona-corona line pairs. We also measure the phase delays between flux and velocity oscillations (I-V). Results: .The phase delays measured between different line pairs, when plotted over a -180 ° to +180 ° range, line up along diagonal lines corresponding to measurable and fixed time delays. The slopes of these diagonal lines suggest the outward propagation of waves. Using the measured time delays, we estimate propagation speeds for the different line pairs that indicate that the waves producing the observed phase delays are magnetoacoustic waves propagating at speeds close to the sound speed. In addition, we find that the phases occur at fixed integer frequencies of f/4 (90 °) and 3f/16 (67.5 °), instead of the expected interval of f (360 °), indicating that a “Doppler effect” is acting on the waves. Conclusions: .From I-V measurements, we find evidence for fast magnetoacoustic waves to be predominantly present at coronal temperatures, while at transition region temperatures slow magnetoacoustic waves are more common. We find strong evidence for outwardly propagating slow magnetoacostic waves in off-limb polar regions and an indication that these propagating waves are influenced by some form of resonant cavity through which they pass.

Affiliated with

Also associated with

No associations

Rating

Magnetoacoustic wave propagation in off-limb polar regions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Magnetoacoustic wave propagation in off-limb polar regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetoacoustic wave propagation in off-limb polar regions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1855011