Abstract
Unique timelapse sequences of Skylab/ATM spectroheliograms reveal the following characteristics of normal (i.e. non-flare) loop structures in the solar atmosphere:
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(1)
At the 0.5 × 106 K temperature of Ne vii, emission is concentrated into individual spiky structures that project 104–105 km from their magnetic footpoints and live on the order of 30 min.
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(2)
At the 1.0 × 106 K temperature of Mg ix, the individual spikes are more diffuse, and have greater lengths and longer lifetimes (∼ 1.5 hr) than their 0.5 × 106 K counterparts. Perhaps for this reason, more 1.0 × 106 K loops are visible than 0.5 × 106 K loops at any given time.
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(3)
At the 2.0 × 106 K temperature of Fe xv, emission is confined to a number of relatively diffuse and irregularly shaped features whose collective patterns define closed field volumes in and between active regions. Although the individual features evolve on a time scale of roughly 6 hr, their collective patterns last for several days or more. Unlike the 0.5 × 106 K features, the 2.0 × 106 K features never form as a linear extension along an apparent magnetic field line, but seem to brighten and fade in place.
These results place severe constraints on theoretical models of coronal heating and mass flow.
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References
Foukal, P.: 1978, Astrophys. J. 223, 1046.
Orrall, F. Q.: 1980, Skylab/ATM Workshop Series Monograph on Active Regions, (in preparation).
Schmahl, E. J. and Orrall, F. Q.: 1979, Astrophys. J. Letters 231, L41.
Schmahl, E. J., Foukal, P. V., Huber, M. C. E., Noyes, R. W., Reeves, E. M., Timothy, J. G., Vernazza, J. E., and Withbroe, G. L.: 1974, Solar Phys. 39, 337.
Sheeley, Jr., N. R.: 1974, unpublished 16 mm Movies of NRL Skylab/ATM Spectroheliograms
Sheeley, Jr., N. R. and Golub, L.: 1979, Solar Phys. 63, 119.
Sheeley, Jr., N. R., Bohlin, J. D., Brueckner, G. E., Purcell, J. D., Scherrer, V. E., and Tousey, R.: 1975a, Solar Phys. 40, 103.
Sheeley, Jr., N. R., Bohlin, J. D., Brueckner, G. E., Purcell, J. D., Scherrer, V. E., and Tousey, R.: 1975b, Astrophys. J. Letters 196, L129.
Tousey, R., Bartoe, J.-D. F., Bohlin, J. D., Brueckner, G. E., Purcell, J. D., Scherrer, V. E., Sheeley, Jr., N. R., Schumacher, R. J., and VanHooser, M. E.: 1973, Solar Phys. 33, 265.
Vaiana, G. S. and Rosner, R.: 1978, Ann. Rev. Astron. Astrophys. 16, 393.
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Sheeley, N.R. Temporal variations of loop structures in the solar atmosphere. Sol Phys 66, 79–87 (1980). https://doi.org/10.1007/BF00150520
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DOI: https://doi.org/10.1007/BF00150520