Engineering topics

Rivolo, A. R.

Publications and source records attributed to Rivolo, A. R..

6 records

NASA NTRS1990

A study of the Baldwin effect in the IUE data set

The paper investigates the controversial relation between the continuum luminosity and the C IV 1550 emission-line strength in the spectra of quasars, commonly referred to as the Baldwin effect, as a possible indicator of absolute luminosity. It is concluded that the Baldwin effect does represent a physical correlation between the continuum and the C IV 1550 equivalent width rather than a consequence of selection effects. In addition to the C IV results, a similar relation is found for the Lyman-alpha emission line.

Kinney, A. L.↗

NASA NTRS1987

Masses, luminosities and dynamics of galactic molecular clouds

Star formation in galaxies takes place in molecular clouds and the Milky Way is the only galaxy in which it is possible to resolve and study the physical properties and star formation activity of individual clouds. The masses, luminosities, dynamics, and distribution of molecular clouds, primarily giant molecular clouds in the Milky Way are described and analyzed. The observational data sets are the Massachusetts-Stony Brook CO Galactic Plane Survey and the IRAS far IR images. The molecular mass and infrared luminosities of glactic clouds are then compared with the molecular mass and infrared luminosities of external galaxies.

Solomon, P. M.↗

NASA NTRS1985

Infrared polar brightening on Jupiter. III - Spectrometry from the Voyager 1 IRIS experiment

Spectra from the Voyager 1 IRIS experiment confirm the existence of enhanced infrared emission near Jupiter's north magnetic pole in March 1979. The spectral characteristics of the enhanced emission are consistent with a Planck source function. A temperature-pressure profile is derived for the region near the north magnetic pole, from which quantitative abundance estimates of minor species are made. Some species previously detected on Jupiter, including CH3D, C2H2, and C2H6, have been observed again near the pole. Newly discovered species, not previously observed on Jupiter, include C2H4, C3H4, and C6H6. All of these species except CH3D appear to have enhanced abundances at the north polar region with respect to midlatitudes. Upper limits are determined for C4H2 and C3H8. The quantitative results are compared with model calculations based on ultraviolet results from the IUE satellite. The plausibility of the C6H6 identification is discussed in terms of the literature on C2H2 polymerization. The relation of C6H6 to cuprene is also discussed.

Kim, S. J.↗

NASA NTRS1981

Observations of Uranus, Neptune, and Titan by the International Ultraviolet Explorer

The ultraviolet spectra of Uranus, Neptune, and Titan do not reveal absorption features at 7-A resolution from 2100 to 3200 A. Upper limits of from 1 to 3 A are set for the equivalent widths of narrow absorptions, which corresponds to a CO/H2 mixing ratio less than 2 x 10 to the -4th in the case of Uranus. The slopes of the continuum reflectivities of Uranus and Neptune are consistent with the semi-infinite Rayleigh-Raman scattering model of Cochran, while the absolute levels are matched only if solar photometry is modified within acceptable limits. An alternative, but less satisfactory explanation of the new data is that the UV reflectivities of both Uranus and Neptune are depressed uniformly by a continuum absorber. The suggestion by Savage et al (1980) that the albedo of Uranus decreases by approximately 20% from 2200 to 1800 A is not confirmed. For Titan, the albedo decreases monotonically toward shorter wavelengths down to 2300 A. New limits are set for the pressure level in the atmosphere of Titan up to which the real, but presently unidentified, UV absorber there must extend, and for the fraction of Titan that must be covered by this absorber

Caldwell, J.↗

NASA NTRS1980

An upper limit to the global SO2 abundance on Io

An upper limit to the global abundance of SO2 gas in the atmosphere of Io has been derived from observations of near-UV reflectivity made from earth orbit. Spectra in the range 2900-3100 A were obtained by the long-wavelength spectrograph of the IUE, and compared with the convolved solar spectrum of Broadfoot (1972). From the apparent solar origin of all the spectral features, an upper limit of 0.008 cm atm was calculated for the abundance of SO2, which was confirmed by ratio spectra of Vesta. Discrepancies between the upper limit obtained and the detection of a column abundance of 0.2 cm atm by the Voyager 1 IRIS experiment have a number of possible explanations, the most likely of which is that the SO2 atmosphere in Io is patchy, being confined to regions over solid deposits and volcanic vents.

Butterworth, P. S.↗

NASA NTRS1980

Observations of the spectrum of Jupiter from 1500 to 2000 A with the IUE

The paper examines the far-UV spectrum of Jupiter recorded by observations with the International Ultraviolet Explorer, noting that only the upper levels of the plant's atmosphere are sampled. It is shown that there are several absorptions caused by C2H2 and indications that NH3 may also be present at these altitudes. In addition, it is suggested that PH3 may also play a role as a continuum absorber, and a new upper limit of 5 x 10 to the -9 on H2S/H2 forbidden line ratio. It is concluded that these results are consistent with existing models for Jovian photochemistry and atmospheric structure.

Owen, T.↗