ScienceProblem: SolarCoronalWaves

PrimaryActor:

Astronomer

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ScienceGoal:

There has been much debate recently about whether large scale coronal waves and chromospheric waves are related. The latter are known as Moreton waves, and were discovered by Moreton and collaborators in the 1960s (e.g. Moreton 1961; Athay & Moreton 1961). Moreton waves was found to propagate large distance away from a solar flare site with velocities ranging from a few hundred to several thousand km/s. Due to the high speeds observed, it was assumed that the origin of the Moreton wave was in the corona and not in the chromosphere. Coronal waves were first observed by the EUV Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft (Thompson et. al. 1999). They appeared in difference images as a bright front with a following dimmed or depleted region of the corona with propagation speeds of a few hundred km/s. Few coronal waves and Moreton waves (observed from ground-based observatories) have been observed simultaneoutsly, and there has been little or not spectroscopic information for the coronal waves (e.g. Harra & Sterling (2001)). The goal is to determine whether coronal wave are MHD fast mode waves occurring from a solar flare site, or if they are a global coronal mass ejection lifting off the surface of the disk.

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DataSets:

SOHO EIT, TRACE, SOHO CDS, Halpha

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ProblemDescription:

Coronal waves have been observed on the Sun regularly since SOHO was launched. They are generally related to solar flares and are a global phenomena that can travel across the entire Sun's disk in less than an hour.

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CurrentSolution:

Current solution is time consuming data trawling. Finding the 'perfect' dataset has as yet not been achieved. This dataset would have to have coronal and chromospheric imaging AND spectral datasets. The spectral datasets are critical for understanding what type of wave we areactually seeing from the velocity measurements.

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VOSolution:

Find as many examples of coronal waves that have at least one hours coverage of all the required datasets. This will involve searching for flares, preferably occuring on disk centre, isolating the times, and then finding the necessary datasets (EUV and Halpha spectra, EUV/SXR imaging).

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Discussion:

Coronal waves are as yet not understood, and are a relatively new phenomena. They are a global phenomena, and must be occuring on other stars.

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Iteration Breakdown:

• Astrogrid.Itn04SolarCoronalWaves - science workflow for case in Iteration 04
• Astrogrid.Itn06SolarCoronalWaves - science workflow for case in Iteration 06
• Astrogrid.Itn08SolarCoronalWaves - science workflow for case in Iteration 08

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KeyReferences:

Athay, R. and Moreton, G.E., 1961, Astrophysical Journal, vol. 133, p.935

Harra, L.K., and Sterling, A.C., 2001, Astrophysical Journal, Volume 561, Issue 2, pp. L215

Moreton, G.E, 1960, Astronomical Journal, Vol. 65, p. 495

Thompson, B. J., Reynolds, B., Aurass, H.,Gopalswamy, N., Gurman, J. B., Hudson, H. S., Martin, S. F., \& St. Cyr, O. C. 2000, Sol. Phys., 193, 161.

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GoodStyle: Please add comments below. This area should be used for refinement of the above document. If you want to ask questions or start a dialogue with the author, please use (or create) a topic in the Science Problems Forum. For other ScienceProblems, refer to the ScienceProblemList.
Author: Once the refinements here and comments in the forum die down, perhaps you could rewrite the problem, incorporating the comments and refinements.

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H-alpha data not available in AstroGrid. Only space-based observations available through UK sites are part of the planned AstroGrid programme. Required data could be sourced through EGSO.

-- BobBentley - 27 Apr 2002

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The coronal waves are first found using image subtraction techniques. Might require generation of image recognition s/w. This could be a Solar AG driver.

-- NicholasWalton - 17 Apr 2002

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-- LouiseHarra - 07 Mar 2002

• An example of a coronal wave. The 'wave' spreads a: