High-spatial-resolution observations of dust and gas in NGC 7027 and the M8 hourglass

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:7059267

Woodward, C E

The spatial relationships among the distribution of the ionized gas, continuum dust emission, and the unidentified 3-12 ..mu..m infrared dust feature emission yield important clues to the identification of candidate grain/molecule materials responsible for feature emission, and provide observational constraints useful in the evaluation of proposed emission mechanisms. Here the results are presented of a systematic study of the 3.28-..mu..m and 3.4-..mu..m dust emission features, two of the unidentified emission bands' frequently detected in the 2-4 ..mu..m band of a variety of astronomical sources, in two energetically and morphologically dissimilar objects: the planetary nebula NGC 7027 and the M8 Hourglass HII region. Comparison and analysis of the moderate spectral resolution (..delta..lambda/lambda approx. 1%), high spatial resolution (approx. 0.4''/pixel) infrared images of NGC 7027 in the 3.28-..mu..m dust-emission feature and the Br..cap alpha.. (4.052 ..mu..m) hydrogen recombination line clearly show that the 3.28-..mu..m emission is spatially more extended than that of the ionized gas. Most of the 3.28-..mu..m feature emission arises from a thin shell, approx. 1'' thickness, at least partially outside of the HII region. Based on a simple model for the source morphology, we conclude that the 3.28-..mu.. emitters are quite robust, because they are able to survive the extremely hard ultraviolet radiation field at the interior edge of the HII region.

• Research Organization: Rochester Univ., NY (USA)
• OSTI ID: 7059267
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
DUSTS
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
FLUIDS
GASES
H2 REGIONS
NEBULAE
PLANETARY NEBULAE
RADIATIONS
RADIOWAVE RADIATION
RESOLUTION
SHORT WAVE RADIATION
SPATIAL RESOLUTION
SPECTRA