Engineering topics

Smith, J. B., Jr.

Publications and source records attributed to Smith, J. B., Jr..

22 records · Page 2

NASA NTRS1977

Coronal plasma parameters in a long-duration X-ray event observed by Skylab

Physical conditions in the solar coronal X-ray-emitting plasma are analyzed for an event observed by the S-056 X-ray telescope on Skylab in August 1973. The event was located at the west limb and consisted of a series of high looplike structures that underwent dramatic changes in structure and intensity for more than 50 hours. A total X-ray energy (8 to 20 A) of about 5 by 10 to the 28th power erg is obtained by integrating over the lifetime and is shown to be equivalent to that reported previously for a 'typical' flare. It is found that a first major peak in total X-ray flux and thermal energy density was due to an increase in temperature, a major secondary peak in these parameters corresponded to the time of maximum in density, and conductivity energy losses near maximum intensity were much greater than radiative losses. Models dealing with sources of heating and energy balance are evaluated.

Vorpahl, J. A.↗

NASA NTRS1977

A long-lived coronal X-ray arcade

A large, long-lived, soft X-ray emitting arch system observed during a Skylab mission is analyzed. The supposition is that these arches owe their stability to the stable coronal magnetic-field configuration. A global constant alpha force-free magnetic field analysis, is used to describe the arches which stayed in the same approximate position for several solar rotations. A marked resemblance is noted between the theoretical magnetic field configuration and the observed X-ray emmitting feature.

Mcguire, J. P.↗

NASA NTRS1976

Results of correlative studies of a complex solar active region /McMath 12387/ during the Skylab mission

Results of correlative studies employing Skylab/ATM X-Ray Telescope filter-heliograms, solar magnetograms, and H alpha spectroheliograms of the complex solar active region McMath 12387 for 10-18 June 1973 are presented. Evolutionary changes within the complex region are discussed. Magnetic field calculations, using both potential and force-free models, have been performed and the results are presented. We also determine temperatures, emission measures, and electron densities and show the variation with time of the X-ray emission from the entire complex.

Smith, J. B., Jr.↗

NASA NTRS1975

Coronal changes associated with a disappearing filament

Skylab/ATM observations of a disappearing filament near the center of the solar disk are described using XUV and H-alpha spectroheliograms, X-ray filterheliograms, and photospheric magnetograms. The temperature of the coronal plasma as the filament disappeared is estimated to have been in excess of 6 million K, and it is noted that the time history of the soft X-ray and microwave fluxes displayed the gradual-rise-and-fall (GRF) signature, suggesting that the present event may have properties that are characteristic of a wide class of long-duration X-ray and radio events. A comparison with other spatially resolved long-duration X-ray events indicates that all such long-lived bursts involve transients in the outer corona and that some two-thirds of them involve either the eruption or the major activation of a prominence. It is also found that long-lived events are characterized by the appearance of new emission loops in the lower corona during the declining phase of the X-ray emission and that these loops sometimes disappear after the X-ray events and sometimes remain indefinitely.

Sheeley, N. R., Jr.↗