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Withbroe, G. L.

Publications and source records attributed to Withbroe, G. L..

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

A model for the polar transition layer and corona for November 1967.

A model for the chromospheric-coronal transition layer and lower corona has been constructed for the south polar region. EUV observations acquired by the Harvard OSO-4 experiment in the fall of 1967 were used in the analysis. The observations can be explained with a simple model consisting of two types of regions. One region has a temperature-density structure similar to that in models developed for typical equatorial quiet areas. The other region has a corona in which the temperature and density are a factor of about 2 lower and the chromospheric-coronal temperature gradient is less steep by a factor of 4.

Withbroe, G. L.↗
NASA NTRS1972

The solar EUV-emitting plasma.

The extreme ultraviolet (EUV), covering a decade in wavelength from about 300 A to about 3000 A, is considered. The general characteristics of the quiet solar atmosphere are reviewed, with emphasis on how the observed emission may be used as a tool to infer this structure. Many of the same techniques are applied to the study of overall properties of active regions.

Noyes, R. W.↗
NASA NTRS1972

Properties of a coronal 'hole' derived from extreme-ultraviolet observations.

A description is given of the results of an analysis of EUV observations of a large coronal hole observed by the Harvard College Observatory (HCO) experiment on OSO-4 in 1967, November. Models were constructed for the chromospheric-coronal transition and coronal layers of the two types of regions. A comparison of the model of the hole and the normal quiet sun indicates that the electron pressure in the hole is reduced by a factor of three and the coronal temperature is lower by 600,000 K.

Munro, R. H.↗
NASA NTRS1972

The derivation of temperature gradient and electron density maps from EUV spectroheliograms.

We discuss spatial variations in electron density at the base of the corona and in the temperature gradient in the chromospheric-coronal transition layer as determined from analysis of maps constructed from Mg X and O VI spectroheliograms. Both the mapping techniques and results of analyzing EUV spectra from OSO 6 observations are presented. Comparisons of these maps with photospheric magnetograms and spectroheliograms made in chromospheric EUV lines and continua indicate that the electron density and temperature gradient in the transition layer tend to be enhanced in areas where the photospheric magnetic field and chromospheric EUV emission are enhanced. Relationships among the coronal electron density, transition-layer temperature gradient, chromospheric emission, and photospheric magnetic field strength are derived.

Withbroe, G. L.↗
NASA NTRS1971

The chemical composition of the photosphere and the corona

Collected photospheric and coronal abundances are presented in tables as summarized from a variety of references. A fairly complete picture of the composition of the solar photosphere for the first 92 elements is developed. Photospheric and coronal abundances are equal to within a factor of 2 (0.3 dex).

Withbroe, G. L.↗
NASA NTRS1971

Real time control of the observing program of an Orbiting Solar Observatory.

Discussion of some innovations in the ground control optimization of the modes of data acquisition once an instrument is in orbit, as illustrated by the Harvard experiment on OSO 6. A detailed description is given of the instrumentation on board OSO 6 which provided a capability of performing spatial scans of the solar disk and the ability to obtain the spectra of selected features on the solar disk. The method of receiving and displaying the data transmitted by the satellite in real time is described, as well as the procedure followed in developing preflight observing objectives and in evaluating completed observations. A typical process of data acquisition to obtain wavelength scans of selected features on the solar disk is illustrated, and a number of collaborative investigations involving simultaneous coordinated observations from the ground and from space are cited.

Reeves, E. M.↗
NASA NTRS1969

The solar

Solar Fe II lines theoretical equivalent widths calculations, estimating influence of photosphere model on iron abundance data

Withbroe, G. L.↗