scholarly journals The Distribution of Radio Brightness over the Solar Disk at a Wavelength of 21 Centimetres. II. The Quiet Sun ? One-dimensional Observations

1953 ◽  
Vol 6 (3) ◽  
pp. 262 ◽  
Author(s):  
WN Christiansen ◽  
JA Warburton
Keyword(s):  
Brightness Distribution ◽  
Lower Envelope ◽  
Solar Model ◽  
Radio Brightness ◽  
Preliminary Calculation ◽  
One Dimensional ◽  
Quiet Sun ◽  
Dimensional Distribution ◽  
Small Change ◽  
Shape And Size

Daily records of one-dimensional distribution of radio brightness over the Sun are obtained in the way described in Part I of this series (Christiansen and Warburton 1953). When superimposed, these records show a well-marked lower envelope which remains substantially the same, in shape and size, over a period of months. This envelope gives the brightness distribution over the "quiet" Sun. The direction of scan, with respect to the position of. the solar axis, changes during a year by more than 50�. The very small change in shape of the envelope during this period suggests that for purposes of preliminary calculation the brightness distribution may be assumed to be circularly symmetrical. The radial distribution of brightness, calculated on this basis, is found to show marked limb-brightening and to be consistent with the calculated brightness distribution for a simple solar model in which the assumed values of temperature and density are close to those commonly accepted.

scholarly journals Solar Brightness Distribution at a Wavelength of 60 Centimetres. I. The Quiet Sun

1955 ◽  
Vol 8 (4) ◽  
pp. 487 ◽  
Author(s):  
G Swarup ◽  
R Parthasarathy
Keyword(s):  
Solar Cycle ◽  
Brightness Distribution ◽  
Central Meridian ◽  
The Sun ◽  
Two Dimensional ◽  
Radio Brightness ◽  
One Dimensional ◽  
Quiet Sun ◽  
Solar Brightness

A multiple-element interferometer has been employed to determine one-dimensional distributions of radio brightness over the quiet Sun at a wavelength of 60 cm for scanning directions varying from 90� to 60� with respect to the central meridian of the Sun. These observations have been compared with measurements by other workers at the same, or nearly the same, wavelength. The present observations are reasonably consistent with the two-dimensional brightness distribution derived recently by O'Brien and Tandberg-Hanssen with a two-aerial interferometer, but do not agree with the earlier results of Stanier at the same wavelength. The disagreement, largely the absence of the theoretically predicted limb-brightening in Stanier's results, may reflect actual changes in the Sun over the solar cycle. However, the possibility of localized disturbed regions affecting Stanier's results for the quiet Sun cannot be eliminated.

scholarly journals The Distribution of Radio Brightness over the Solar Disk at a Wavelength of 21 Centimetres. III. The Quiet Sun ? Two-Dimensional Observations

1955 ◽  
Vol 8 (4) ◽  
pp. 474 ◽  
Author(s):  
WN Christiansen ◽  
JA Warburton
Keyword(s):  
Solar Disk ◽  
Fourier Method ◽  
Brightness Distribution ◽  
Sunspot Activity ◽  
Polar Regions ◽  
Two Dimensional ◽  
Radio Brightness ◽  
One Dimensional ◽  
Quiet Sun ◽  
Coronal Electron

A distribution of solar radio brightness at a wavelength of 21 cm has been derived from observations made during the period of low sunspot activity from 1952 to 1954. The observations were made using two multiple interferometers arranged at right angles; this enabled the solar disk to be scanned in many different directions. The derived one-dimensional profiles of the quiet Sun for these various scanning directions were combined and a Fourier method adopted to derive a two-dimensional brightness distribution. The distribution shows marked limb-brightening in the equatorial zones but none in the polar regions. The contours of brightness are in general conformity with those expected from a solar atmosphere having a coronal electron density distribution of the kind proposed by van de Hulst for the period of minimum sunspot activity.

scholarly journals The quiet sun at 88-cm wavelength

1959 ◽  
Vol 9 ◽  
pp. 107-107
Author(s):  
J. Firor
Keyword(s):  
Brightness Distribution ◽  
Lower Envelope ◽  
The Sun ◽  
One Dimensional ◽  
Quiet Sun ◽  
The One

An attempt has been made to measure the one-dimensional brightness distribution of the sun at 88-cm wavelength. Strip scans of the sun made with a 4′.8 fan beam have been superimposed and the lower envelope drawn, after the manner of Christiansen [1].

scholarly journals The Radio Brightness of the Quiet Sun at 21 cm Wavelength Near Sunspot Maximum

1960 ◽  
Vol 13 (4) ◽  
pp. 700 ◽  
Author(s):  
NR Labrum
Keyword(s):  
Active Regions ◽  
Residual Effects ◽  
High Angular Resolution ◽  
Radio Brightness ◽  
Sunspot Maximum ◽  
One Dimensional ◽  
Quiet Sun ◽  
Limits Of Error ◽  
Very High ◽  
Intense Radiation

An investigation has been made of the radio emission from the quiet Sun at 21� 2 em wavelength in 1958 (near sunspot maximum). Two different methods have been used, both involving observations with very high angular resolution, to distinguish between the quiet-Sun component and the radiation from localized active regions. In one method, the Sun was scanned with a narrow pencil-beam; in the other, a fan-shaped aerial beam was used to give one-dimensional strip scans. In both cases it was necessary, when analysing the data, to take into account the residual effects of the very intense radiation from the localized sources. The two independent measurements gave results which agree within the limits of error. The apparent disk temperature was found to be approximately 140 000 oK, or twice the value for the same wavelength at sunspot minimum.

scholarly journals The Distribution Of Radio Brightness Over The Solar Disk At A Wavelength Of 21 Centimetres. I. A New Highly Directional Aerial System

1953 ◽  
Vol 6 (2) ◽  
pp. 190 ◽  
Author(s):  
WN Christiansen ◽  
JA Warburton
Keyword(s):  
Transmission Lines ◽  
Solar Disk ◽  
Brightness Distribution ◽  
Resolving Power ◽  
Radio Brightness ◽  
One Dimensional ◽  
Multiple Beams ◽  
Rotation Of The Earth ◽  
Very High ◽  
East West

A new aerial system of very high resolving power has been designed for use in determining the distribution of radio brightness across the solar disk at a wavelength of 21 cm. Thirty-two aerials with paraboloidal reflectors are evenly spaced in an east-west direction over a distance of about 700 ft., and are connected by a branching system of balanced open-wire transmission lines to a receiver. The aerial system produces multiple beams each 3' of arc wide and spaced 1.7� apart. The rotation of the Earth causes one after another of the aerial beams to scan the disk of the Sun. The record obtained from the radio receiver gives a one-dimensional brightness distribution over the solar disk.

scholarly journals 51. Interpretation of solar radio-frequency disk brightness distributions derived from observations with aerials extended in one dimension

1957 ◽  
Vol 4 ◽  
pp. 290-293 ◽  
Author(s):  
S. F. Smerd ◽  
J. P. Wild
Keyword(s):  
Solar Radio ◽  
Synthesis Method ◽  
One Dimension ◽  
Solar Model ◽  
Two Dimensional ◽  
Fourier Synthesis ◽  
One Dimensional ◽  
Finite Resolution ◽  
Dimensional Distribution ◽  
The Individual

Several recent papers have dealt with observations of brightness distributions over the solar disk, which were derived either from two-aerial interferometer observations at various spacings and orientations (e.g. O'Brien, 1953) [1], or from multiple-element interferometer fan-beam observations at various orientations (e.g. Christiansen and Warburton, 1954) [2], In each a two-dimensional distribution is derived from a number of essentially one-dimensional observations by a Fourier synthesis method described by O'Brien. The detail given by these methods must be limited by the finite resolution of the individual observations (limited by the maximum aperture of the aerial system), but the form of the limitation is not obvious, though its knowledge is required when relating the observations to a solar model.

Slit Type One-Dimensional Brightness Distribution Sensor

2014 ◽  
Author(s):  
Shota Nakashima ◽  
Shenglin Mu ◽  
Shintaro Okabe ◽  
Tatsuya Ichikawa ◽  
Kanya Tanaka ◽  
...  
Keyword(s):  
Brightness Distribution ◽  
One Dimensional

Quasi-one-dimensional distribution of macropores in anodically etched uniaxially stressed silicon plates

2003 ◽  
Vol 29 (3) ◽  
pp. 226-229 ◽  
Author(s):  
V. I. Emel’yanov ◽  
K. I. Eremin ◽  
V. V. Starkov ◽  
E. Yu. Gavrilin
Keyword(s):  
One Dimensional ◽  
Dimensional Distribution ◽  
Stressed Silicon

scholarly journals The Radio Brightness Distribution on the Sun at 21 cm from Combined Eclipse and Pencil?Beam Observations

1961 ◽  
Vol 14 (3) ◽  
pp. 403 ◽  
Author(s):  
T Krishnan ◽  
NR Labrum
Keyword(s):  
High Resolution ◽  
High Sensitivity ◽  
Brightness Distribution ◽  
Pencil Beam ◽  
The Sun ◽  
Radio Brightness ◽  
Radio Brightness Distribution ◽  
Grating Interferometer

A study of the brightness distribution on the Sun at 21-cm wavelength on April 8, 1959, is described. High resolution observations were made of the partial eclipse on that day with a simple radiometer of high sensitivity. The brightness distribution of the uneclipsed Sun at the same wavelength was obtained using a cross-grating interferometer, which enabled the bright regions to be located accurately.

Sign in / Sign up

Export Citation Format

Share Document