Leo Goldberg

The Abundances of the Elements in the Solar Atmosphere.

The method of weighing functions was utilized to derive the abundances of forty-two elements from faint and medium-strong lines is the solar spectrum. The model atmosphere adopted was that of Aller and Pierce as extended by Elste to both higher and deeper layers. The chief sources of equivalent widths were the measurements by Allen and by the Utrecht astronomers, but a substantial number of new measurements were included from McMathHulbert Observatory data. The f-values were taken from many different sources, but, whenever possible, experimental measurememts were employed. When laboratory data were not available, they were replaced by theoretical values based on the assumption of LS coupllng and making; use of the f-sum rule or of the Bates and Damgaard tables for the absolute scale factor. A detailed description is given of the derivation of the abundance of each element, including the major sources of uncertainty, such as the errors in the measurement of weak lines throughout the spectrum and of all lines in the ultraviolet region, uncertainties in the solar model for ultraviolet lines, and tbe unreliable character of many of the f-values employed. (auth)

Solar abundance determination from ultraviolet emission lines

The intensities of far ultraviolet emission lines from the solar corona are analyzed to determine relative coronal abundances for oxygen, silicon, and iron. Dielectronic recombination is included in the formulation of ionization equilibrium. Observations of solar radio emission are used to obtain abundances relative to hydrogen. The absolute coronal abundances appear to be in agreement with their respective photospheric values. General properties of the structure of the chromosphere and corona are deduced from the analysis of observed emission in the ultraviolet and radio wavelength regions.

Coronal electron density maps for 7 March, 1970, derived from Mgx λ625 spectroheliograms

We have analyzed daily Mgx λ 625 spectroheliograms acquired by the Harvard College Observatory experiment on OSO-6 for a 28-day period centered on 7 March, 1970, the date of a well-observed total solar eclipse. These data are used to construct maps of the variation across the solar disk of the electron density at the base of the corona. The correspondence of high and low density regions with regions of enhanced and reduced emission in white light and Mgx pictures made during or near the time of the eclipse are described.

The Harvard experiment on OSO-6 - Instrumentation, calibration, operation, and description of observations.

The Harvard experiment carried by OSO-6 was an extreme-ultraviolet (EUV) spectrometer-spectroheliometer with a wavelength range of 285 to 1385 A, a spatial and spectral bandwidth of 35 x 35(arc sec) squared and 3 A, respectively. The instrument acquired data that have been deposited with the National Space Science Data Center and World Data Center A at the Goddard Space Flight Center in Greenbelt, Maryland, and are now available in their entirety to the scientific community. Aspects of the experiment that are relevant to potential users of the data are described - namely, instrument configuration and parameters, laboratory and inflight calibrations, as well as operational capabilities and procedures. The observations obtained are reported, and the nature, number, and dates of observation, where relevant, are listed.

The Vertical Distribution of Nitrous Oxide and Methane in the Earth’s Atmosphere*

The intensities of the atmospheric lines P25, P26, P27, and P29 of the 2.16-μ band of N2O and of the 5–6 line of the 1.66-μ band of CH4 have been measured in the spectrum of the low-sun observed from Mount Wilson. For both molecules, the rate of change of intensity with solar zenith angle is inconsistent with the existence of these gases in thin layers at altitudes of 15 km or greater. On the other hand, the observations satisfy very well the assumption of uniform mixing with the major constituents of the atmosphere.

CARBON MONOXIDE IN THE ULTRAVIOLET SOLAR SPECTRUM.

Abstract : The laboratory absorption spectrum of CO at approximately 5000K has been studied in a shock tube and appears to account for some of the observed features of the solar rocket ultraviolet spectrum. (Author)

Experimental Determination of Absolute f-Values for Methane

The absolute f-values of rotational lines in the positive and negative branches of the 2ν3 overtone band of CH4 have been derived from absorption measurements in the laboratory by two independent methods. The first method involves the use of the curve of growth and requires the observation of weak lines for which the total absorption is independent of the damping constant. In the second method the lines are broadened artificially, by the introduction of about 3 atmos of air, to half-widths that are about five times the slit width. The f-values are then determined by integration of the logarithm of the percentage absorption over the line profile. On the average, the f-values obtained by the two methods agree within 10 percent.

Recent advances in infra-red solar spectroscopy

(i) Carbondioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 (ii) Methane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 (iii) Nitrous oxide . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 (iv) Water vapour . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 9 5 . Telluric lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Photosphere of the Sun

An empirical model of the photosphere rests on observations of: (1) the solar constant—which fixes the temperature scale, (2) limb darkening—from which the variation of temperature with depth throughout the atmosphere is determined, and (3) the energy distribution—which, together with limb darkening, reveals the opacity at each depth and for each wavelength.

THE ABUNDANCE OF He

Various investigations on the presence of He/sup 3/ in the sun and the isotopic ratio of He/sup 3//He/sup 4/ are discussed. Probable errors and discrepancies are noted and a value for the He/sup 3//He/sup 4/ ratio is obtained. (W.D.M.)