Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-Velocity Upflows?

Details Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-Velocity Upflows? Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-Velocity Upflows?

2010-08-31

arxiv.org/abs/1008.5300v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

To appear Astrophysical Journal. 14 pages, 13 color figures, 4 movies. High resolution figures and online supporting movies ar

Scientific paper

Since the discovery of quasi-periodic propagating oscillations with periods of order three to ten minutes in coronal loops with TRACE and EIT (later with EUVI and EIS), they have been almost universally interpreted as evidence for propagating slow-mode magnetoacoustic (MA) waves in the low-beta coronal environment. We show that this interpretation is not unique. We focus instead on the ubiquitous faint upflows, associated with blue asymmetries of spectral line profiles in footpoint regions of coronal loops, and as faint disturbances propagating along coronal loops in EUV/XR imaging timeseries. The two scenarios are difficult to differentiate using only imaging data, but careful analysis of spectral line profiles indicates that faint upflows are likely responsible for some of the observed quasi-periodic oscillatory signals in the corona. We show that EIS measurements of intensity and velocity oscillations in coronal lines (previously interpreted as direct evidence for propagating waves) are actually accompanied by significant oscillations in the line width that are driven by a quasi-periodically varying component of emission in the blue wing of the line. The faint blue-shifted emission component quasi-periodically modulates the peak intensity and line-centroid of a single Gaussian fit to the profile with the same small amplitudes (respectively a few percent of background intensity, and a few km/s) used to infer the presence of MA waves. Our results indicate that a significant fraction of the quasi-periodicities observed with coronal imagers and spectrographs, previously interpreted as propagating MA waves, are caused by these upflows. The different physical cause for coronal oscillations would significantly impact the prospects of successful coronal seismology using propagating disturbances in coronal loops.

Affiliated with

Also associated with

No associations

Rating

Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-Velocity Upflows? 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 Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-Velocity Upflows?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-Velocity Upflows? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-180391