Summary: DUST PROPERTIES IN THE FAR-ULTRAVIOLET IN OPHIUCHUS
N. V. Sujatha, P. Shalima, and Jayant Murthy
Indian Institute of Astrophysics, Koramangala, Bangalore 560 034, India; firstname.lastname@example.org,
Richard Conn Henry
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218; email@example.com
Received 2005 May 6; accepted 2005 July 5
We have derived the albedo (a) and phase function asymmetry factor (g) of interstellar dust grains at 1100 8 using
archival Voyager observations of diffuse radiation in Ophiuchus. We have found that the grains are highly forward-
scattering, with g ¼ 0:55 Æ 0:25 and a ¼ 0:40 Æ 0:10. Even though most of the gas in this direction is in the
Ophiuchus molecular cloud, the diffuse FUV radiation is almost entirely due to scattering in a relatively thin fore-
ground cloud. This suggests that one cannot assume that the UV background is directly correlated with the total
amount of gas in any direction.
Subject headinggs: dust, extinction -- infrared: ISM -- ultraviolet: ISM
The Ophiuchus molecular cloud is one of a large complex of
clouds at a distance of about 160 pc from the Sun (Chen et al.
1997). The region has been extensively studied in CO (de Geus