F. C. Gillett

8 to 13 micron spectra of NGC 7027, BD + 30

Observations of the 8 to 13, mu spectra of the planetary nebulae NGC 7027, BD + 30 deg 3639, and NGC 6572 are presented. The spectra consist of both fine-structure line radiation and continuum radiation. The results are discussed in terms of abundances, predicted line strengths, and composition of radiating material. (auth)

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Nearly complete 2 to 13 ..mu..m spectra are presented for 13 compact infrared sources associated with molecular clouds, as well as partial spectra of six additional objects. The spectra resemble blackbodies with superposed absorption features from 2.8 to 3.5 ..mu..m, at 6.0 and 6.8 ..mu..m, and in the silicate band centered near 9.7 ..mu..m. Correlations among the features are studied in an attempt to confirm possible identifications. A good correlation between the deepest part of the absorption at 3.1 ..mu..m, its long wavelength wing, and the 6.0 ..mu..m features suggests that all may be due to large amorphous water ice particles. The relatively poor correlation between the 3.4 and 6.8 ..mu..m optical depths adds no evidence to support the suggestion that these bands may be due to CH bonds.

3639, and NGC 6572

A total of 86 galaxies have been detected at 60 μm in the high galactic latitude portion of the IRAS minisurvey. The surface density of detected galaxies with flux densities greater than 0.5 Jy is 0.25 deg^(-2). Virtually all the galaxies detected are spiral galaxies and have an infrared to blue luminosity ratio ranging from 50 to 0.5. For the infrared-selected sample, no obvious correlation exists between infrared excess and color temperature. The infrared flux from 10 to 100 μm contributes approximately 5% of the blue luminosity for galaxies in the magnitude range 14 < m_(pg) < 18 mag. The fraction of interacting galaxies is between one-eighth and one-fourth of the sample.

Infrared spectra of protostars - Composition of the dust shells

Jupiter spectrum observations in 2.8-14 micron range, describing absorption strength and brightness temperature, basing analysis on ammonia, methane and hydrogen absorption

Infrared galaxies in the IRAS minisurvey

The spectrum of the highly obscured infrared source W33 A from 4.5 to 8 microns is measured in order to investigate the intervening cold, dense interstellar material. Spectrophotometry at a relative spectral resolution of about 0.015 by an airborne filter-wheel infrared spectrometer reveals strong absorption features at 4.61, 5.99 and 6.78 microns. The absorption at 4.61 microns is attributed primarily to the fundamental vibration-rotation band of CO at a column density (at least 10 to the 19th/sq cm) which is 10% of the carbon inferred from silicate abundances. The strengths and line widths of the absorption agt 5.99 and 6.78 microns are interpreted as evidence of absorption in the resonance bands of carbonyl, carbon-carbon double, methyl and methylene bonds of hydrocarbons associated with interstellar dust.

The 2.8-14-micron spectrum of Jupiter.

Narrow-band observations of Titan at selected wavelengths in the 8- to 13-micron range show evidence for a strong temperature inversion and the existence of at least one more spectroscopically active component in the atmosphere in addition to H2 and CH4.

The 4-8 micron spectrum of the infrared source W33 A

IRAS satellite IR observations are presently used to investigate the properties of the dust in a small sample of irregular galaxies chosen to cover a wide range in levels of star formation activity. The irregulars are found to have comparatively normal IR properties; the only exception is NGC 1569, an irregular galaxy with intense global star formation which seems to have a larger dust fraction at temperatures whose energies peak at 25-60 microns, by comparison with other irregulars. DDO 47, the system with lowest star formation activity, has the lowest far-IR color temperature and highest ratio of IR to H-alpha flux; this is suggested to be due to the decreased importance of radiation from young stars in heating the dust.

8-13 micron observations of Titan.

Stellar spectra observed with 2.8-14 micron IR spectrometer, noting broad absorption feature near 5 and 8 microns

IRAS observations of a small sample of blue irregular galaxies

The IRAS source 13349 + 2438 is a quasar with a redshift of z = 0.107, broad (15,000 km/s) emission lines and a luminosity of 2.7 x 10 to the 12th solar luminosity, emitted mostly between 4.8 and 12 microns. The object, a weak radio source, is the first previously unidentified quasar selected through its infrared emission and is the prototype radio-quiet, infrared-bright quasar. A dusty interstellar medium may be responsible for the infrared emission as well as for quenching the visual emission and attenuating the radio emission from the central energy source.

Stellar spectra from 2.8 to 14 microns.

IRAS observations of the extreme hydrogen-deficient supergiant R CrB are presented and discussed. The star is surrounded by an enormous cool dust cloud which is tentatively identified as a fossil remnant of the hydrogen-rich envelope of the star. The angular extent of the emission corresponds to a linear extent of 8 pc, 20 times larger than the largest previously known shell around a late-type star. The radiating material is distributed very symmetrically over a wide range of radial distances from the star. The dust temperature is nearly constant throughout the extended shell. The total mass in the shell is about 0.3 solar mass. The ejection process appears to have occurred in a spherically symmetric fashion with a nearly constant mass loss rate and expansion velocity over a period of about 150,000 yr, terminating about 26,000 yr ago.