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The Diffuse Extreme Ultraviolet Background

Published online by Cambridge University Press:  12 April 2016

John Vallerga
Affiliation:
Eureka Scientific Inc., 2452 Delmer St. Suite 100, Oakland, CA 94602-3017, USA
Jonathan Slavin
Affiliation:
Eureka Scientific Inc., 2452 Delmer St. Suite 100, Oakland, CA 94602-3017, USA

Abstract

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Observations of the diffuse EUV background towards 138 different directions using the spectrometers aboard the Extreme Ultraviolet Explorer satellite (EUVE) have been combined into a spectrum from 150Å to 730Å and represent an effective exposure of 18 million seconds. There is no significant evidence for any line flux from any source other than the geocorona. These results are inconsistent with the Wisconsin C and B broad-band surveys assuming the source is a logT = 5.8 – 6.1 hot plasma in ionization equilibrium with solar abundances, confirming the previous result of Jelinsky, Vallerga & Edelstein (1995) (hereafter Paper I) using an observation along the ecliptic with the same instrument. To make these results consistent with the previous broad-band surveys, the plasma responsible for the emission must either be depleted in Fe by a factor of ~ 6, be behind an absorbing slab of neutral H with a column of 2×l019cm−2, or not be in collisional ionization equilibrium (CIE). One particular non-CIE model (Breitschwerdt & Schmutzler, 1994) that explains the soft x-ray results is also inconsistent with this EUV data.

Type
Part III Observations and Modeling of the Local Bubble and the SXRB
Copyright
Copyright © Springer-Verlag 1998

References

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Jelinsky, P., Vallerga, J. and Edelstem, J.(1994): ApJ, 442, pp. 653661 (Paper I)Google Scholar