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Macy, W., Jr.

Publications and source records attributed to Macy, W., Jr..

17 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Raman scattering in the Jovian atmosphere

On December 8 and 9, 1976, the 1024 channel Reticon silicon photodiode array detector in the coude spectrograph of a 2.7 m telescope was used to obtain spectra of Jupiter and the moon. Three separate data sets were obtained, including one of the Jovian equatorial region, one of the Jovian north polar cap, and one of Mare Serenetatis on the moon. A correlation analysis was conducted. The autocorrelation function of the Jovian spectrum was calculated and the autocorrelation function of the lunar spectrum was subtracted from it. The analysis made it possible to detect Raman scattering by H2 in the atmosphere of Jupiter. The pure rotational H2 S(0) and S(1) lines were detected. The ratio of the relative number of Raman scattered photons in the S(0) and S(1) features indicate that the H2 in the Jovian atmosphere is in the equilibrium, rather than the normal state. Therefore some sort of nonradiative process is responsible for transitions between the ortho and para states of H2.

Cochran, W. D.↗
NASA NTRS1980

Measurements of the H2 4-0 quadrupole bands of Uranus and Neptune

It is found that the equivalent widths of the lines of the 4-0 H2 quadrupole band on Uranus and Neptune are substantially smaller than the values found by some previous observers. An analysis of the results based on a range of atmospheric models yields H2 abundances of 240 + or - 60 km-amagats for Uranus and greater than approximately 200 km amagats for Neptune.

Smith, W. H.↗
NASA NTRS1979

On the clouds of Uranus

Several models for the atmosphere of Uranus are considered. If the H2 abundance is less than 250 km-am and the internal heat source is only a few percent of the total emitted energy then the cloud at the base of the atmosphere may be composed of solid CH4 particles, while if the H2 abundance is greater than 250 km-am or if the internal heat source is near the current upper limit of 35% of the total emitted energy the cloud at the base of the atmosphere may be composed of either solid NH3 or H2S particles.

Macy, W., Jr.↗
NASA NTRS1979

On seasonal phenomena in Saturn's atmosphere - New observations of Saturn's 3nu3 methane band

Saturn's 3nu3 CH4 band has been reobserved during April-June 1976, using the same telescope and spectrographic set-up used to study this band during the 1970 apparition. Direct comparison of the ratio spectra Saturn/moon reveals greater absorption in the manifold cores during 1976, but the increase is not as pronounced as that for the stronger CH4 bands. The rotational temperature and effective pressure of this band did not change significantly. These results are interpreted in terms of a possibly seasonal settling of the upper boundary of Saturn's atmospheric haze layer.

Trafton, L.↗
NASA NTRS1979

The diameter and reflectance of Triton

The surface reflectance, radius and geometric albedo of Triton are investigated. Image tube spectra of the reflectance of the satellite between 3200 and 7400 A are presented which indicate that the surface is composed mainly of rocky (non-icy) material, with violet absorption suggesting a composition similar to that of lunar fines, terrestrial igneous rocks and chondrites. Photometric/radiometric calculations based on measurements of the 20-micron thermal flux and the known visual magnitude of Triton reveal an upper limit of 5280 km to its diameter, and a lower limit of 0.19 to its geometric albedo. Computations of Rayleigh scattering in a potential inert atmospheric component are also presented which appear to preclude the presence of large quantities of nitrogen and noble gases on Triton.

Cruikshank, D. P.↗
NASA NTRS1978

Detection of HD on Saturn and Uranus, and the D/H ratio

The HD 5-0 R(0) line on Saturn and Uranus has been observed. Values for the D/H abundance ratio computed from models for the atmospheres of these two planets are 5.5 + or - 2.9 times 10 to the minus fifth power for Saturn and 3.0 + or - 1.2 times 10 to the minus fifth power for Uranus. The D/H ratio for Jupiter of 5.1 + or - 0.7 times 10 to the minus fifth power found from a measurement of the HD 4-0 P(1) line is bracketed by the values found for Saturn and Uranus.

Macy, W., Jr.↗
NASA NTRS1978

On the distribution of sodium in the vicinity of Io

The contribution of scattering in a telescope to measurements of the size of Io's sodium cloud and to the distribution of emission intensity in the cloud is investigated. The brightest regions, within 30 arcsec of Io near opposition and along the equatorial plane, are relatively undistorted, but regions further than 45 arcsec away and not close to the equatorial plane are very likely to consist mainly of scattered light. Portions of the cloud in the vicinity of the magnetic equator are also mostly scattered light when Io is near extreme magnetic latitude. The equatorial torus, however, extends up to 20 arcmin from Jupiter. The large size of the cloud is thus confirmed. High-resolution line profile shapes indicate that sodium streams from Io preferentially in the forward direction with velocities distributed up to 18 km/sec. The observed wavelength shifts of the peak intensities from Io's rest frame are compatible with a cloud streaming through a bound atmospheric component, but they could also be caused by a velocity distribution peaked at very low velocities.

Trafton, L.↗
NASA NTRS1977

Venus - On the phase variation of CO2 line profiles

The shapes of Venus' CO2 profiles are found to vary with solar phase angle. High-resolution spectra of the P16 and P14 lines in the 8689- and 7820-A bands, respectively, are presented for phase angles ranging from 6 to 158 deg. The scattering mean free path at 80 mbar, approximately the effective pressure, is 1.7 km. Use of the van de Hulst (1974) similarity relations with simple parametric scattering models is inadequate to separate effects due to the scattering phase function from those due to inhomogeneities in depth when one attempts to determine the atmospheric structure by fitting a family of such models over a wide range of phase angles.

Macy, W., Jr.↗
NASA NTRS1977

Io's sodium emission profiles - Variations due to Io's phase and magnetic latitude

We present recent measurements of high-resolution sodium D2 emission line profiles of Io's atmosphere and cloud. The high-velocity skirts of these profiles are strongest when Io is on the magnetic equator where protons and heavy ions, which sputter atoms from Io's surface, are concentrated. The skirts are most prominent on the long-wavelength side of the line when Io is west of Jupiter, and they are most prominent on the short-wavelength side of the line when Io is east of Jupiter. Our observations also indicate that there is a shift in the emission peak with respect to Io which is correlated with Io's orbital phase angle.

Trafton, L.↗
NASA NTRS1976

An analysis of Saturn's methane 3 nu /3/ band profiles in terms of an inhomogeneous atmosphere

Observed profiles of the R branch of Saturn's CH4 3 nu (3) band are compared with synthetic profiles computed from inhomogeneous models which are consistent with Saturn's H2 quadrupole-line equivalent widths. A C/H ratio approximately three times the solar value and a CH4 abundance of about 100 m am are found. Scattering plays a significant role in the formation of manifold profiles below a depth where the H2 abundance is 20-30 km am.

Macy, W., Jr.↗
NASA NTRS1975

An oscillating asymmetry to Io's sodium emission cloud

The spatial distribution of sodium emission north and south of Io was observed to have a time-dependent asymmetry correlated with Io's magnetic latitude. The spatial gradient was greatest when Jupiter's north magnetic pole pointed away from Io; this is a configuration of maximum probability of decametric emission. A hypothesis is invoked for explaining the asymmetry and used to calculate preliminary fluxes of low-energy trapped charged particles in the vicinity.

Trafton, L.↗
NASA NTRS1975

A model for Io's atmosphere and sodium cloud

Observations of the sodium D-line emissions associated with the Galilean satellite Io suggest that the emitting region has two components. The first is an atmosphere which extends 1000 km above Io's surface. This is a relatively dense region which is optically thick in the sodium D lines. The second component is a surrounding optically thin cloud spread out along Io's orbit to form part of a torus. No emission was detected during any of three eclipses observed, although Io's sodium emission was consistently present when Io was near orbital elongation. This indicates that resonant scattering is the principal emission mechanism in both components. For the atmosphere, measurements of the D-line intensity, D-2/D-1 ratio, and line width indicate a temperature of 500 to 1000 K and a sodium column abundance of 3 by 10 to the 13th power per sq cm. Upper limits to the abundance of Mg, K, Ca, and Li indicate a high sodium abundance ratio in the atmosphere. This may also be true for Io's surface if sputtering by energetic particles is the source of the atmosphere. The sodium cloud has been detected as far as 60 arcsec from Io in the orbital plane and at least 6 arcsec above and below this plane. The cloud can be sustained by atoms escaping from the critical level at the top of the atmosphere.

Macy, W., Jr.↗
NASA NTRS1975

Saturn's 3 nu 3 methane band - An analysis in terms of a scattering atmosphere

Using parameters recently measured in the laboratory, the shapes of manifolds belonging to the R-branch of Saturn's 3 nu 3 CH4 band were analyzed in terms of a homogeneous scattering model of Saturn's atmosphere, and the results were compared with those of an earlier analysis in terms of a reflecting-layer model. The resulting effective pressure is an order of magnitude smaller than for the reflecting-layer analysis, and the C/H ratio is an order of magnitude higher than the solar value. The overall fit of the theoretical profiles to the observed manifold shapes is distinctly worse, especially for R(7). Scattering evidently plays only a minor role in the formation of this band along Saturn's south-central meridian.

Trafton, L.↗
NASA NTRS1974

The Spatial Extent of Sodium Emission Around Io

The sodium D emissions associated with Io's spectrum also originate in a large volume of space surrounding the satellite, extending more than 10 arc sec in radius. Although this region extends well beyond the equilibrium point between Jupiter and Io, no emission torus has been detected around Jupiter. The emission, however, appears to be stronger close to Io's orbital plane and especially on the Jovian side of Io. Resonant scattering is a viable excitation mechanism in the cloud, and in any case provides an upper limit to the column abundance.

Trafton, L.↗