AAS 199th meeting, Washington, DC, January 2002
Session 151. Structure and Composition of The ISM
Oral, Thursday, January 10, 2002, 2:00-3:30pm, Jefferson West

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[151.02] Determination of the Far-Ultraviolet Dust Scattering Properties in NGC 2023

E.B. Burgh (UW-Madison)

The reflection nebula NGC~2023 was observed by a rocket-borne long-slit imaging spectrograph in the 900--1400~Å\ bandpass on 11 Feb 2000. A spectrum of the central star, HD~37903, as well as that of the nebular scattered light was recorded. Through the use of a Monte Carlo modeling process, the scattering properties of the dust were derived. The albedo is low, 0.2--0.4, and decreasing toward shorter wavelengths, while the phase function asymmetry parameter is consistent with highly forward-scattering grains, g~.85. The decrease in albedo, while the optical depth increases to shorter wavelengths, implies that the far-UV rise in the extinction curve is due to an increase in absorption efficiency.

This work was supported by NASA grant NAG5-5122 to the Johns Hopkins University.

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