arXiv subjects

P. Shalima

Publications and source records attributed to P. Shalima.

21 records · Page 2Linked to original sources

arXiv2006

FUV Scattering by Dust in Orion

We have modelled diffuse far-ultraviolet spectrum observed by FUSE near M42 as scattering of starlight from the Trapezium stars by dust in front of the nebula. The dust grains are known to be anomalous in Orion with Rv = 5.5 and these are the first measurements of the FUV optical properties of the grains outside of ``normal'' Milky Way dust. We find an albedo varying from 0.3 $\pm$ 0.1 at 912 Åto 0.5 $\pm$ 0.2 at 1020 Åwhich is consistent with theoretical predictions.

astro-ph↗

arXiv2005

Dust Properties in the FUV in Ophiuchus

We have derived the albedo ($a$) and phase function asymmetry factor ($g$) of interstellar dust grains at 1100 Å~ using archival {\it Voyager} observations of diffuse radiation in Ophiuchus. We have found that the grains are highly forward scattering with $g =$ 0.55 $\pm$ 0.25 and $a =$ 0.40 $\pm$ 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 foreground cloud. This suggests that one cannot assume that the UV background is directly correlated with the total amount of gas in any direction.

astro-ph↗

arXiv2003

Modeling of Dust Scattering in the Coalsack

Murthy et. al.(1994) discovered intense UV (1100 Å) emission from the directi on of the Coalsack Nebula. We have used their results in conjunction with a Mon te Carlo model for the scattering in the region to show that the scattering is from dust in the foreground of the Coalsack molecular cloud. We have constrained the albedo of the grains to 0.4 $\pm$ 0.1. This is the first determination of the albedo of dust in the diffuse ISM in the FUV.

astro-ph↗