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THE LOCAL INTERSTELLAR ULTRAVIOLET RADIATION FIELD Richard Conn Henry1
 

Summary: THE LOCAL INTERSTELLAR ULTRAVIOLET RADIATION FIELD
Richard Conn Henry1
Center for Astrophysical Sciences, Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University,
Baltimore, MD 21218; henry@jhu.edu
Received 2001 July 20; accepted 2002 January 16
ABSTRACT
I have used the Hipparcos Input Catalogue, together with Kurucz model stellar atmospheres and informa-
tion on the strength of the interstellar extinction, to create a model of the expected intensity and spectral dis-
tribution of the local interstellar ultraviolet radiation field, under various assumptions concerning the albedo
a of the interstellar grains. (This ultraviolet radiation field is of particular interest because of the fact that
ultraviolet radiation is capable of profoundly affecting the chemistry of the interstellar medium.) By compar-
ing my models with the observations, I am able to conclude that the albedo a of the interstellar grains in the
far-ultraviolet is very low, perhaps a 0:1. I also advance arguments that my present determination of this
albedo is much more reliable than any of the many previous (and conflicting) ultraviolet interstellar grain
albedo determinations. Beyond this, I show that the ultraviolet background radiation that is observed at high
Galactic latitudes must be extragalactic in origin, as it cannot be backscatter of the interstellar radiation field.
Subject headings: dust, extinction -- ultraviolet: general
1. INTRODUCTION
The physics of the local interstellar medium is profoundly
influenced by the intensity and spectrum of the local inter-

  

Source: Henry, Richard C.- Department of Physics and Astronomy, Johns Hopkins University

 

Collections: Physics