Radio observations of the planet Jupiter

Abstract

Radio observations of Jupiter made in June 1954 and November 1, 1955, to March 13, 1956, are reported. Three aspects of the program are discussed: (1) Correlation of observation with the rotation of Jupiter; (2) Polarization of the radiation; (3) Frequency characteristics. During the period of observation, there were at least three centers of activity on the planet, rotating approximately with the non‐equatorial regions. No definite correlation of radio noise with visible features was noted. The white spot DE, noted as a possible correlation in 1951 data, was definitely not well correlated with radio noise occurrences in 1955–56. The most active radio region exhibited a rotational period of 9h55m33s, a value consistent with other determinations and also consistent with the suggested long‐term rotational period, system III. Most of the radio noise bursts were strongly circularly polarized. For the most active region, only bursts of right circular polarization were observed. The radio noise spectrum does not appear to be continuous over the observed set of frequencies. The hypothesis that the narrow angle of visibility is evidence for critical reflection by the ionosphere of Jupiter is not supported by the combined Carnegie and Australian observations.

Radio Spectrum of Jupiter

“…We now know that this conclusion was correct, although Shain's value: of 28 seconds for the difference between the periods was excessive. Later evaluations ( 3 , 9,10,13) placed the difference closer to 10 or 11 seconds, and a recent redetermination by our group, using data which now extend over a decade, has given a figure of 9"55"'29'.35 for the rotation period of the radio sources (5). Since J. N. Douglas and H. J. Smith recently derived, by an independent method, a value which differs from ours by only 0.02 second (II), the period now seems to be established with high precision.…”

“…Observations made simultaneously on channels differing in frequency by several megacycles per second seldom show much correlation between individual pulses, and it is clear that this places an upper limit on the band-width (4, 9). For several years we have been conducting experiments with two receivers connected to the same antenna.…”

Synchrotron Radiation as the Source of the Polarized Decimeter Radiation from Jupiter.

“…while the third type consists of bursts of radiation which last seconds or minutes and which occur only in a narrow band of frequencies between abo'.lt 15 and 25 Mel sec. Right-hand circular polarization haa been reported for a number of bursts [Franklin and Burke (1958)}. The bursts seem to originate in a small area, and the determination over a five year interval of the Jovian period of rotation from the bursts has indicated a quite constant period [Carr, Smith, Pepple, and Barrow (1958»).…”

Space environment and magnetospheric Poynting fluxes of the exoplanet $τ$ Boötis b

“…The success of radio observations has been demonstrated in the past in the solar system. For example, Jupiter's magnetic field was discovered through radio observations (Franklin & Burke 1958) before spacecraft confirmed it with in-situ magnetometer measurements. Since τ Boötis b may be the first exoplanet with a directly observed magnetic field it provides an unique opportunity to constrain the space environment around this exoplanet.…”