Diffraction-limited ten micron imaging of circumstellar dust with a detector array
An imaging system was constructed that achieves diffraction-limited spatial resolution (about 0.6'') at a wavelength of 10 ..mu..m on large telescopes. The system uses an array of 25 photovoltaic detectors in the focal plane, arranged along two crossed arms. The very small physical size of individual detectors, and the use of drift scans with a stationary telescope, permit reliable imaging on a spatial scale not easily probed before. Several broad-band interference filters (with ..delta..lambda/lambda approx. = 0.1) permit imaging on and off the 9.7 ..mu..m spectral feature due to silicate dust particles. The array system was used to map the circumstellar dust envelopes of several late-type stars, including ..alpha.. Scorpii, ..alpha.. Orionis, and IRC + 10216. The first two objects, oxygen-rich type M supergiants, show faint extended emission around an unresolved stellar photosphere which dominates the surface brightness. Particularly accurate east-west profiles of the brightness distributions are obtained, and in the case of ..alpha.. Orionis a distinct east-west asymmetry was observed in February 1983. This asymmetry, to which previous interferometric imaging techniques would not have been sensitive, apparently indicated the presence of a bright discrete cloud about 0.9'' to the west of the photosphere, superimposed on fainter, more extended thermal radiation from dust. Observation of this source one year later revealed a substantial decline in the flux from the discrete cloud, by a factor of at least two.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 6163700
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
COSMIC DUST
IMAGE SCANNERS
INTERSTELLAR SPACE
STARS
BRIGHTNESS
MAPPING
PHOTOVOLTAIC CELLS
DIRECT ENERGY CONVERTERS
DUSTS
OPTICAL PROPERTIES
PHOTOELECTRIC CELLS
PHYSICAL PROPERTIES
SPACE
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources